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Trace-ElementAnalysisin ClinicalChemistry

Henry A. Schroeder and Alexis P. Nason

Present knowledge of human bodily contents and concentrations in blood,urine, and hair of 11 essential trace elements and 17-22 nonessential inert ortoxic trace elements is reviewed and summarized. Analyses of trace ele-ments are applicable as diagnostic aids and indices for therapy in a numberof clinical conditions. Techniques are not difficult, and analyses will prob-ably become more or less routine for many diseases in which primary orsecondary abnormalities are manifest. Trace elements play fundamentalroles in human metabolism.

Additional Keyphrases micronutrients . diagnostic aids #{149} physiologicaland abnormal trace elements #{149} carcinogens #{149} vascular disease #{149} normal

values

Burgeoning knowledge on the role of traceelements in biological systems is beginning to focusattention on their place in human metabolism.Essential trace elements are necessary not only foroptimal function of the mammalian organism, forgrowth, healing, and activity of many metabolicprocesses, but for life itself. They are probablyconcerned with longevity.

Present in the primitive seas, they were un-doubtedly used by the first living organisms ascatalysts for simple biochemical reactions, forstructure and for bridging of organic molecules (1).Elements that were abundant in the oceans andthose with atomic configurations and electro-chemical properties suitable for these functionswere “chosen;” more than half of the elements inthe Periodic Table were unsuitable, either becauseof wrong configurations or scarcity. As livingorganisms became more complex, these very basicelements were used for more and more complexreactions, often linked to protein as enzymatic co-factors.

Of the first 20 elements of the Periodic Table,12 are bases of organic molecules, electrolytes, orstructures, three are noble gases, two (boron andfluorine) have functions for living things, andthree apparently are functionless (lithium, beryl-lium, and aluminum). Of the next 14, 11 are essen-

From the Department of Physiology, Dartmouth MedicalSchool, Hanover, N. H., and the Brattleboro Memorial Hospital,Brattleboro, Vt. 05301.

tial for some form of life as trace elements. Onlytwo essential elements, molybdenum and iodine,have atomic numbers greater than 34.

As living things evolved, they made severalevolutionary “mistakes” by using an element foran essential function that was adequate for aprimitive function, but was unsuitable for furtherevolution. Vanadium is used in the blood cells ofascidians; their larvae have a notochord and arerelated to our vertebrate ancestor, Amphioxus,but adults have only a single ganglion for a nervoussystem, an example of evolutionary regression (2).Vanadium is also used by a bryozoan, a mollusc, aholothurian, and certain nitrogen-fixing bacteria,fungi, and algae, especially Amanita muscaria.Copper is used in the blood of worms, crustacea,molluscs, and insects (1) instead of iron, which ismore efficient for oxidation-reduction reactions.

Certain elements accumulate in one or moremarine plants and animals: silver, aluminum,arsenic, barium, bromine, cadmium, cerium, nio-bium, neodymium, nickel, praseodymium, scan-dium, tin, tantalum, titanium, uranium, zirconium.Certain specialized land plants accumulate thefollowing elements in their tissues and can act as“indicator” plants for them: silver, aluminum,gold, barium, copper, erbium, europium, fluorine,mercury, holmium, iodine, lanthanum, lithium,lutetium, neodymium, nickel, lead, praseodymium,selenium, samarium, tin, terbium, thulium, ura-nium, vanadium, yttrium, ytterbium, and zinc (1).

In a few cases, these indicator plants, which

CLINICAL CHEMISTRY, Vol. 17, No. 6, 1971 461

462 CLINICAL CHEMISTRY, Vol. 17, No. 6, 1971

reveal the presence of high concentrations of theelement in soil, seem to require it; in most cases itis probably inert.

There are 12 trace elements that are recognizedas performing functions essential to life or healthof living organisms. Of them, six are essential forall forms of life: manganese, iron, cobalt, copper,zinc, and molybdenum. All plants require boron;most require vanadium; some need chromium.Mammals need iodine, fluorine, selenium, andchromium. It is suspected, but not proven, thatvanadium and nickel may he needed by mammalsfor some function.

Our purpose here is to call attention to theextremely important roles these micronutrientsplay in mammalian, and especially human metabo-lism, and to indicate how the clinical chemist canhelp to diagnose diseases and disturbances byanalyzing biological material for them.

In mammals and man, a trace element is definedas one that makes up less than 0.01% of the body’smass. Together, the 50 or more trace elementsfound in the body, both normal and abnormal,make up less than 0.2% of the total weight of thebody. Iron, fluorine, and zinc, the most abundanttrace elements, comprise 0.006%, 0.0037%, and0.0033% of the body, respectively. By comparison,the least abundant bulk elements, magnesium andsilicon, make up 0.027% and 0.026%, respectively,of the body.

There are two general classes of abnormalitiesassociated with trace elements: specific defi-ciency-from dietary inadequacies, imbalances, orsecondary to other diseases-and accumulation ofinnately toxic trace elements from the environ-ment, which can either displace essential elementsfrom their metabolically active sites and cause con-ditioneci deficiency, or act directly as cellulartoxins. Both kinds of abnormalities can be diag-nosed by analyses of trace elements in plasma orserum, red blood cells, and urine. Furthermore,secondary changes occur as a result of systemicdisease; they are not understood.

Analytical Methods

Methods of ashing and analysis must be tailoredto the special qualities of each element sought, andof the material being analyzed (2-24).

Elements that are relatively highly concentratedin biological material-such as iron, copper, andzinc, and the bulk elements, magnesium andcalcium-must frequently be determined in di-luted serum, plasma, or urine, whereas thosepresent in lower concentrations can be analyzeddirectly or may even require concentrating.

Dry ashing in muffle furnaces at 400-450#{176}Cissatisfactory for most metals. Volatile elements suchas selenium, tellurium, fluorine, iodine, mercury,antimony, and arsenic requiie the lower tempera-

tures afforded by wet ashing or a low temperatureasher (Tracerlab LTA-600A, ICN, Irvine, Calif.92675). A mixture of nitric, sulfuric, and per-chloric acids, sometimes with added sodiummolybdate, has been found to be a suitable solu-tion for wet ashing most biological material. Bothwet ashing and the LTA have the disadvantage ofbeing restricted to small samples (1-2 g). Wetashing is rapid, generally taking no more than30 mm, whereas the LTA may require 24 to 48 h ormore.

The atomic absorption spectrophotometer hasproved to be a most useful and versatile piece ofapparatus for trace-element analysis. This deviceis relatively inexpensive for analytical equipment,and can be used for the accurate analysis of atleast 14 elements of biological interest at concen-trations in aqueous media of 0.5 to 0.003 g/g, andsensitivities of 0.2 to 0.01 g/g per 0.01 absorbance(Table 1). When precautions are taken, repro-ducibility is in the order of 5-10%.

An air-acetylene flame is satisfactory for cad-mium, calcium, chromium, cobalt, copper, iron,lead, manganese, magnesium, nickel, strontium,and zinc. For vanadium and molybdenum, use ofthe higher temperature nitrous oxide-acetyleneflame is either necessary or desirable to obviatecertain interference effects. This method is rela-tively insensitive for antimony, tellurium, andvanadium in our experience, and the literatureindicates that this is also the case for boron,zirconium, niobium, aluminum, and uranium.

With special but simple apparatus, mercury canbe determined as a static vapor in an absorptioncell without use of a flame.

Ancillary equipment and new tecimiquesundergo continuous development. The use ofN20 with a special burner has been mentioned asyielding improved results for certain refractoryelements. A three-slot burner (Boling burner)allows aspiration of concentrated solutions andbiological fluids with minimal clogging and, more-over, an increase in sensitivity for many elementsby a factor of two or more. The sampling boat, aPerkin-Elmer product, consists essentially of asmall tantalum foil trough in which a sample isevaporated before being placed in the flame.Volatilization is virtually instantaneous, and theabsorption is recorded as a sharp peak on a fastrecorder. For lead, zinc, and cadmium, and some ofthe more volatile elements mentioned above thatdo not require high temperatures for dissociation,this technique can prove most useful. It requiresvery small samples and considerably lowers thelimits of detection found by conventional atomicabsorption techniques.

Modifications are available or built into manyinstruments, which allow such elements as sodium,potassium, lithium, rubidium, and barium, amongothers, to be determined by flame emission.

Element

Atomic absorption

Calcium 0.1 0.01 Cadmium 0.05 0.005Magnesium 0.01 0.003 Lead 0.2 0.05Chromium 0.07 0.02 Mercury 0.001kgManganese 0.05 0.01 Antimony 0.7 0.25Iron 0.15 0.01 Beryllium 0.03 0.002Cobalt 0.13 0.01 Tin 1.2 0.2Copper 0.07 0.005 Barium 0.36 0.05Zinc 0.04 0.005 Aluminum 1.3 0.1Molybdenum 0.8 0.5 Titanium 2.0 0.1Strontium 0.1 0.02 Arsenic 2.0 0.5NickeI’ 0.15 0.05 Lithium 0.04 0.005Vanadium’ 1.7 0.08 Rubidium 0.2 0.005

Photofluorometric


Table 1. Analytical Methods, Sensitivities, and Limits of Detection for Elements in Blood, Urine,Tissues, and Hair

Essential elements Nonessential elements

Sensitivity,Sensitivity,M9/g per 1% Limit of ,g/g per 1% Limit ofabsorption detection, pg/g Element absorption detection, p9/9

CotorimetricMolybden urnVanadium’ManganeseChromiumNickelb

1.OgO.51zg0.01 g0.0060.05

LeadTinArsenicTitaniumGermaniumNiobiumZirconiumBoron

0.05kg

0.5 g0.250.10.040.80.5

Selenium 0.1kg Beryllium 0.002,zg

Ion.specific electrode

Fluorine 0.02 Bromine 0.4Iodine 0.007

Flame photometric

LithiumRubidium

0.0000030.001

Selenium, fluorine, bromine, and mercury require wet-ashing; arsenic, antimony, and germanium require wet or low-temperature ashing. All others can be dry.ashed in a muffle furnace at 400-450#{176}Cin silica crucibles. Calcium, mag-nesium, zinc, and copper can be measured in fluids directly or by dilution.

Sensitivity in terms ofg/g per 0.01absorbance unit is shown only for atomic absorption spectrophotometry. Limit of detectionis usually shown in Jhg/g(or,Lg/ml) as least concentration detectable. When shown asg, it is the smallest amount detectable by dif-ference in two solutions, both with known amounts added; e.g., when a blank with 5pg added differs from the unknown with 5g addedby 0.1 g, that is the value shown.

Data from Schroeder et al. (-24) and Perkin-Elmer’s Analytical Methods for Atomic Absorption Spectrophotometry (25, 26).Essentiality for mammals unproven.

Procedures for solvent extraction are numerousand have in common the advantages of concentra-tion of the element in question, separation frommatrix and from other possibly interfering ele-ments, and generally enhanced sensitivity. Theseand many other developments are amply docu-mented in standard texts (25), specialized periodi-cals (26), and elsewhere in the literature.

For a number of elements of biological interest,atomic absorption has not been found suitable, butspecific colorimetric methods are available and

practical, as we have found for molybdenum (12),

vanadium (2), tin (10), arsenic (16), titanium (14),niobium (18), zirconium (17), and boron (tin-published). In our experience the standard dithi-zone method for lead is more sensitive and accuratethan atomic absorption, especially for smallsamples. Selenium (11) can be determined byphotofluorometry, as can a few other elements.Ion-selective electrodes have been used in com-bination with a pH meter to determine fluoride ion,and are available for a number of other elements.

ElementBody

mg pg/gBlood

RemarksPlasma RBC

mg total

Iron 4200 60 2500 3.6 2400 70.5% in hemoglobinFluorine 2600 37 0.95 0.87 0.17 98.9% in boneZinc 2300 33 34 5.6 2.8 65.2% in muscleStrontium 320 4.6 0.18 0.17 0.008 99% inboneCopper 72 1.0 5.6 3.5 2.2 34.7% in muscleSelenium 13 0.2 1.1 ... ... 38.3% inmuscleManganese 12 0.2 0.14 0.025 0.12 43.4% in boneIodine 11 0.2 0.29 2.6 0.35 87.4% in thyroidMolybdenum 9.3 0.1 0.083 ... ... 19% inliverChromium 1.7 0.02 0.14 0.074 0.044 37% inskinCobalt 1.5 0.02 0.0017 0.0014 0.00034 18.6% inbone (marrow)

Possibly essentialNickel 10 0.1 0.16 0.09 0.07 18% in skinVanadium <18 0.3 0.088 0.031 0.057 >90% infat

“Data of Tipton (27) and Bowen (1).

Element

Table 3. Abnormal Trace Elements of Interest in the Human Body and Blood”

mgBody

p9/9Blood Plasma RBC

Remarksmg total

Rubidium 320 4.6 14 2.2 12 FollowspotassiumBromine 200 2.9 24 17 7.5 60% in muscleLead 120 1.7 1.4 0.14 1.2 91.6% in boneAluminum 61 0.9 1.9 1.3 0.14 19.7% in lung, 34.5% in boneCadmium 50 0.7 0.036 .. ... 27.8% in kidney and liverBoron <48 0.7 0.52 ... - . - Essential for plantsBarium 22 0.3 <1.0 <0.62 ... 91% in boneTin <17 0.2 0.68 0.10 0.55 25% in fatand skinMercury 13 0.2 0.026 0.009 0.017 69.2% in fat and muscleTitanium 9 0.1 0.14 0.12 0.08 49.1% in lung and lymph

nodesGold <10 0.1 0.00021 ... - -. 52% inboneAntimony ? 7.9 0.1 2.024 0.16 ... 25% in boneCesium 1.5 0.02 0.015 .. ... Follows potassiumUranium 0.09 0.001 0.0046 . - - . . - 65.5% in boneBeryllium 0.036 ... <0.00052 ... . . - 75% in boneArsenic ? 18 0.3 2.5 <0.093 0.59 FollowsphosphorusLithium 2.2 0.03 0.10 0.093 0.061 50% inmuscleZirconium 420 6.0 13 1.2 12 67% infatNiobium ? 110 1.6 13 <0.25 13 26% infatTellurium ? 8.2 0.1 0.18 0.09 0.078 Probably inbone

“Data of Tipton (27) and Bowen (1).

Table 2. Essential Trace-Element Content of the Human Body and Blood”


Precautions against contamination and theliberal use of blanks are necessary to avoiderroneous results. Heparin, stainless steel, rubberand Pyrex glass are sources of contamination;polyethylene is relatively free of it (1).

The methods we have found useful are listed inour various publications, and are commonplace(2-4, 6-24).

Trace Elements in the Human BodyThe relative amounts of essential and abnormal

trace elements in the body and blood of “ReferenceMan” (27) are listed in Tables 2 and 3. Respectivetotals for the essential elements range from 4.2g t.o 1.5 mg. Principal storage depots are also

indicated. Bodily contents of abnormal or non-essential elements range from 420 mg to 36 gig.

Average or representative dietary balances areshown in Tables 4 and 5, with amounts that can beexcreted in sweat. “Normal” concentrations in hairare also indicated.

Measured balances in long-term studies in-volving many analyses on five subjects are given inTables 6 and 7 to indicate the variations that mayoccur from person to person. These data differ insome respects from those in Tables 4 and 5; theywere obtained by emission spectroscopy on dailydiets duplicating what the persons ate, which werefrozen and stored for long periods. Urine and feceswere also stored (28, 29).

UrineElement Diet, mg/day mg/day % of intake Sweat, mg/day Hair, pg/g

Chromium 0.05-0.1 0.008 8 0.059 0.69-0.96Manganese 2.2-8.8 0.225 6 0.097 1.0Iron 15 0.25 2 0.5 130Cobalt 0.3 0.26 87 0.017 0.17-0.28Copper 3.2 0.06 2 1.59 16-56Zinc 8-15 0.5 5 5.08 167-172Selenium 0.068 0.04 59 0.34 0.3-13Strontium 2.0 0.2 10 0.96 0.05Molybdenum 0.3 0.15 50 0.061 ...

Iodine 0.2 0.175 88 0.006 0.015Fluorine 2.5 1.6 64 0.65 ...

Possibly essentialVanadium 2.0 0.015 1 ... . - -

Nickel 0.4 0.011 3 0.083 0.0075

e Data on diets and urine from Schroeder et al. (2-13), lipton et al. (28,29); on sweat from Consolazio et al. (30); and on hair fromSchroederand Nason (24) and Tipton(27). Diets are average values; there are considerable variations, depending on types of foods.When two values are shown for hair, they are for males and females.

Element

Toxic

Diet, mg/day mg/day % of intake Sweat, mg/day

0.030.030.015

<0.07

Hair, pg/9

1477550

2.8-1.818-1966.5

Table 5. Intakes and Excretions of Abnormal Trace Elements”Urine

Cadmium 0.215Lead 0.450 0.256Mercury 0.02 0.0009Antimony <0.15 0.011Beryllium 0.013 0.0013 10Tin 4.0 0.023 0.6 2.23 .. -

Arsenic 1.0 0.195 20 .. 2Barium 1.25 0.023 2 0.085 5Tellurium 0.112 0.53 47 . . -

NontoxicRubidium 1.5 1.1 74 0.05Bromine 7.5 7.0 93 0.2 12.5Aluminum 45 0.1 0.2 6.13 5Titanium 0.85 0.33 39 0.001 0.05Zirconium &2 0.14 0.3Niobium 0.62 0.36 58 0.003 2.2Lithium 2.0 0.8 40 +Boron 1.3 1.0 77 ... 7

“Data fromSchroederetal.(14-23), Tiptonetal.(28, 29), Howells, G. P. (personal communication), Schroeder and Nason (24)andConsolazioetal.(30). Theseareaveragevalues; wide variations exist, depending on exposures. Toxic refers to innate toxicity, and in thecaseofmercury,thealkylforms.‘Nontoxic”referstorelativelysmalldoses;allelementsare toxicin largeenough amounts.

Table 4. Intakes and Excretions of Essential Trace Elements”


Clinical Applications

Essential Trace Elements

Expected levels of the essential trace elements inplasma and urine are shown in Table 8.

Zinc. Deficiency of zinc owing to marginaldietary intake or excessive urinary losses is prob-ably the most common condition to be expectedtoday (31), especially in older persons. It can bedetected by determining concentrations in plasma;serum zinc concentrations are greater, owing tovariable inclusion of leukocytes and platelets thatcontain much zinc. As zinc is the most concen-

trated intracellular trace element, subnormal con-centrations in plasma probably reflect subnormalconcentrations in cells, just as low serum potassiumconcentrations usually reflect intracellular losses.Oral zinc supplements readily restore plasma con-centrations to normal in most cases.

Oral zinc supplementation represents a majorbreakthrough in the treatment of a variety of con-ditions (31-33). It has doubled the rate of healingof surgical wounds and indolent ischemic ulcers ofthe legs (34, 35). It has controlled intermittentclaudication from partial atherosclerotic occlusionof major arteries, relieved angina pectoris, prob-

Element A B C D E

mg intake and % of intake in urineChromium 0.33 0.40 0.20 0.29 0.20

30 50 55 41 80Manganese 4.39

5.73.459.3

3.31.3

5.5096

9.301

Iron 121.7

150.3

156.1

283.0

222.4

Cobalt 0.17100

0.1688

0.3177

0.4749

0.2955

Copper 1.0432

0.9135

0.952.3

1.72.5

6.20.47

Zinc

Molybdenum..

0.099100

...

0.1071

11120.2152

18670.4628

14390.1124

Strontium 1.3717.5

1.2434

1.963

2.14.8

2.34.3

Possibly essentialNickel 0.39

280.8114

0.2818

Vanadium 0.06130

0.1714

0.06917

Days analyzed 30 30 347 347 70

Element A B C D #{163}

Aluminum 18 225.5 4.5

Barium 1.7716

1.5436

Boron 0.42100

0.35100

Cadmium

Tin 1.497.4

2.483.2

Titanium 0.37100

0.41100

mg intakeand % of intakein urine17 175.1 4.20.65 0.925.7 1.81.2 2.8

100 34

311.51.3L911430.18

Zirconium

Days analyzed

0.10 0.2283 42 615.8 8.8? 6.71.5 0.66 0.030.75 2.0 0.1865 24 890.43 0.55 0.088

20 33 1.930 30 347 347 70


Table 6. Variations in Daily Intake and Urinary Output of Essential Trace MetalsBalance Studies (Analyses by Emission Spectroscopy)”

Subject

during Long Term

“Data from Tipton et al. (28, 29).

Table 7. Variations in Daily Intake and Urinary Output of Abnormal Trace MetalsBalance Studies (Analyses by Emission Spectroscopy)”

____________ Subject

during Long Term

“From Tipton et al. (28, 29).

ably relieved transient cerebral isehemic episodes,and promoted adequate blood flow distal toocclusions despite lowered arterial pressure (33).In older experiments, it has partially reversedabnormal liver function in alcoholic cirrhosis (36).It is most effective when plasma concentrations arelow.

Low plasma zinc has been described in womentaking oral contraceptives, pregnant women, and

patients with active tuberculosis, chronic andacute infections, myocardial infarction, Laennec’scirrhosis of the liver, some cancers, perniciousanemia, leukemia, indolent ulcers, severe athero-sclerosis, malnutrition, uremia, and prolongedpostoperative convalescence (31). Zincuria hadbeen found in nephrosis with heavy proteinuria, inpostoperative states (33), and cirrhosis of theliver (36). Because losses of zinc occur in sweat

Plasma UrineMean Minimum Mean Maximum

Element pg/i00 ml pg/100 ml p9/I pg/I Method

Chromium 2.8 2.0 10(87)’ 40(133) AA(SP)Manganese 0.83 0.25 300(33) 980 C0(SP)Iron 114 90? 180(980) ... CO(SP)Cobalt 0.018 0.007 98(210) 160C AA(SP)Copper 116 100 59(110) (70) AA(SP)Zinc 98 89 900(1800) 1920 AA(SP)Molybdenum 0.4 C 100(140) 150 C0(SP)Selenium 1.1 C 30 C D

Strontium 5.7 3.8 150 420 SPFluorine 2.8 C 1140 2501Y SIodine 8.7 C 125 C CONickel 0.42 0.10 85 100 AACOVanadium 1.0 0.10 16(29) 30 CO(SP)

“Data from Schroeder et al. (2-12) and Bowen (1).Numbers in parentheses are from Tipton et al. (28, 29) by spectrographic method (SP). AA, atomic absorption spectrophotometry;

CO,colorimetry; P, photofluorometry method; S, ion.specific electrode.‘Depends on current intake in food and fluids.

Table 8. Normal Concentrations of Essential Trace Elements in Blood and Urine”


(up to 5 mg/day) (30), in urine (up to 1.0 mg/dayor more), and in semen (1.0-1.7 mg/ejaculate), adeficiency that was marginal may rapidly becomesevere, and healing thereby slowed in patients fedintravenously after surgery.

Elevated concentrations of zinc in plasma havebeen found in hyperthermia (10).

The causes of primary dietary low-grade defi-ciency are clear. The major sources of calories-refined flour, in which 80% of the zinc in wheat isremoved, refined sugar in which 98% of the zinc inraw sugar is removed, and refined fats in whichmost of the zinc is removed-are notably low inzinc (10). These deficiencies are not alwaysbalanced by nuts, meats, whole grains, and sea-foods, which contain adequate zinc.

When present knowledge filters through theusual wall of skepticism, indifference, and igno-rance to the practicing physician, we predict thata general need will arise for the evaluation of thestatus of zinc in patients. Zinc is so vital to thebody’s economy that replacement therapy willbecome as common as, or more common than,therapy with iron. Status will be measured byconcentrations in plasma and red cells, which areindices of cellular zinc, and urinary excretion tomeasure renal retention or excessive losses. Oraldoses of zinc used are 150 mg or more daily as thesulfate or 30 mg as the acetate; we have found thesmaller dose adequate, which represents twice thethe amount in a good diet.

Copper. Low concentrations of cerulopla.smin,elevation of plasma copper not bound to cerulo-plasmin, and hypercupruria are characteristic ofhepatolenticular degeneration (Wilson’s disease).The cause is absence or deficiency of the generesponsible for copper homeostasis. Enormousamounts of copper are accumulated in kidney,

liver, heart, spleen, skin, pancreas, brain, andlung-as much as 100 times normal (8). Positivediagnosis is based on analyses. Although measure-ments of ceruloplasmin are diagnostic of thedisease, it can he suspected if hypercupruria andhypocupremia are found.

Low plasma or serum copper concentrationshave been found in hypoproteinemia, as might beexpected, and in malnutrition. High concentrationshave been reported in various collagen diseases;four-fold concentrations have been found insynovial fluid of patients with rheumatoid arthritis,suggesting a point for differential diagnosis. En-hanced blood concentrations have occurred ininfections, myocardial infarction, hepatic diseases,malignant diseases, various anemias, thyrotoxi-cosis, and perhaps schizophrenia (8).

Iron. Total serum or plasma iron and protein-bound iron can be readily measured by the atomicabsorption spectrophotometer, offering aids todiagnosis of iron storage diseases. Idopathichemochromatosis, which is probably the result ofdeficiency of the gene responsible for iron homeo-stasis, lends itself to analyses of body fluids foriron.

The preceding three trace metals are present inblood and urine in easily measurable amounts, andwith little expense and expenditure of time theiranalyses could become almost routine, with returnsof great importance to the patient. Five othermetals are present in plasma in small amounts, andtheir measurements are more difficult.

Cobalt. Cobalt occurs at the lowest concentra-tions; at present there are no clinical indicationsfor serum or plasma cobalt measurements, the needbeing filled by measurement of vitamin B12.Cobalt has been suspected to play a role in immunereactions (7). Easily measureable amounts occur


in urine, as 87% of the amount in the diet isexcreted by the kidneys. Cobalt may play aprimary or secondary role in cerebral vascularaccidents, and in infections (7)-low tissue con-centrations being found. A study of urinarycobalt in diseases might be rewarding.’

Manganese. Manganese is easily measurable inurine, but plasma or serum require concentrationfor accuracy. It is unlikely that true deficiencystates occur; slow rates of turnover of manganese,which depend on supply, may result in symptoms(6). However, the ratio of daily dietary intake tobody content is the highest of any trace element,3 mg to 12 mg or 1:4. The only measurement ofinterest to the clinician would be urinary levels, asindices of supply and therefore of turnover. Be-cause manganese is essential for glucose and lipidmetabolism, oxidative phosphorylation, and anumber of other basic biochemical processes, it isessential that human beings have adequateamounts. Pregnant women, growing children,adults on unphysiological reducing diets, andpatients with toxemia of pregnancy, disorders ofbony and cartilaginous growth, certain types ofsterility, and disseminated lupus erythematosisdeserve investigation of manganese balance (6).Supplementation with oral manganese is nothazardous.

It is possible that hereditary manganism exists,the gene for homeostasis being deficient. Minersinhaling large amounts of manganese oxide dustssuffer from a disorder resembling Parkinsonism,probably a result of manganese deposits in thebasal ganglia, although this hypothesis has notbeen proven.

Molybdenum. As far as is known, molybdenum isessential for two molybdo-flavoprotein enzymes,xanthine oxidase and aldehyde oxidase-theformer is necessary for the formation of uric acid.Deficiency in man has not been described. Excessin sheep binds copper and causes depigmentationof black wool; by alternately feeding copper andmolybdenum, striped wool can be grown. Sulfate,a member of the same periodic group, interfereswith this molybdate-copper interaction (12). Ex-cess tungsten produces xanthine oxidase deficiency,as well as hyperglycemia; molybdenum may beconcerned in glucose metabolism. Little is knownabout its effects in man.

Strontium. Strontium hardens hones and teeth,and may be anticariogenic, as well as prevent senileosteoporosis. It is not difficult to measure. Stron-tium follows the physiologic pathway of calcium,and 99% of the body content is in bone, for which

Cobalt salts added to beer have been implicated in a number

of cases of myocardial insufficiency. Cobalt, however, has a loworder of toxicity to mammals, and although contributory to thisdisorder, other causal factors were probably also responsible.It is not known whether or not serum levels were diagnostic.

it is probably essential. Its status in senile osteo-porosis should be evaluated. Replacement therapyin deficiency states would offer no hazard.

Fluorine. Fluorine is also most concentrated inbone and teeth; 98.9% of the body’s content isfound there. Levels in blood and urine reflectintake, as this anion is rapidly excreted; blood andurinary levels thus indicate dietary content andlittle more. Need for evaluation of fluorine iii bodyfluids is not apparent at this time.

Selenium. Selenium is essential for mammals,aside from its sparing action on vitamin E, butlittle is known of its physiological significance (11).Deficiency probably does not occur in man, as verysmall amounts are required. Measurements are nottoo exact, even by the best method. At this time,there is no need to measure it.

Chromium. Chromium deficiency is a causalfactor in atherosclerosis (4). Chromium is essentialfor glucose and lipid metabolism. Rats deficient indietary chromium show relative hypercholes-teremia, hyperglycemia, or abnormal glucosetolerance, and atherosclerosis of the aorta, thusreproducing the human disease. Patients dying ofcoronary occlusion have little or no aortic chro-mium, unlike those dying of other causes. Tissuesof American subjects are low or deficient in chro-mium, as compared with tissues of foreigners.Dietary chromium deficiency is wide-spread inthis country, because most of the chromium isremoved when sugar, fats, and flour are refined.The amount required to keep a grown rat inglucose and cholesterol homeostasis is, in humanweight equivalents, 500-700 )Lg/day. The usualhuman diet contains 50-100 tg.

Chromium in the form occurring naturally infoods is probably readily absorbed, whereas only0.5% of chromic salts and simple organic com-plexes pass the wall of the small intestine. Chromicsalts olate in alkaline media, forming largemolecules that cannot be absorbed. A search isunderway for the natural complexes; when they be-come available, replacement therapy for deficiencyand, presumably, for atherosclerosis therapy can beemployed logically. Until that time, sufferers fromthis widespread disease can only eat foods high innatural chromium, such as dark brown sugar andmolasses, whole grains, brown rice, and unrefinedfats. We have found buckwheat, millet, bran,certain breakfast cereals, beets, carrots, peas,butter, margarine, corn sugar, and some rawsugars and syrups to be fairly good sources ofchromium. Refined sugars, grains, and fats arepoor sources (4).

Measurement of chromium is difficult, requiringspecial precautions. Blood and urine contain littlechromium. However, if relatively large amountsare found in the urine, intake is presumablyadequate.

Vanadium and nickel. These are possibly essen-


tial for mammals, although not yet proven so.Vanadium may have a role in cholesterol and fattyacid metabolism, depressing synthesis. Vanadium-manganese antagonisms exist in some forms of life(2). Nickel may play a part in integumentarycolor-or the lack of it (9)-and is probably essen-tial for birds.

In the present state of knowledge, measure-ment of these two elements is more or less acade-mic, except in one condition. In myocardial in-farction, nickel stores are mobilized and enter theblood stream, resulting in significant increases inserum nickel (38). Manganese stores are also mobi-lized similarly, and increases in serum copper havebeen reported. Infarction also results in low level ofplasma zinc. Both nickel (38) and manganese (6)in serum have been proposed as more accurate in-dices of myocardial infarction than serum glutamicoxaloacetic transaminase, which can give false posi-tive results. These outpourings of manganese andnickel are much larger than the total contents ofthe metals in heart muscle, which are 0.066 mgand 0.016 mg, respectively, and must come fromother depots.

Excretion. Of these essential elements, it can beseen from Table 4 that the metals chromium,manganese, iron, copper, zinc, and strontium--which occur as cations-are excreted only sparselyin the urine, probably being bound by bile andexcreted into the intestine. In at least a few ofthem, enterohepatic circulations are involved.Iron, copper, and manganese have specific trans-porl systems, which have not been demonstratedfor the others, but probably exist. When ingested,an amount corresponding to only 2 to 10% of theintake of these metals is excreted by the kidney.Vanadium and nickel behave similarly.

Cobalt and the anions selenate, molybdate, io-dide, and fluoride are excreted in the urine to theextent of 50-88% of dietary contents. With this inmind, one can evaluate the meaning of data onurinary excretion.

Sweat can be a sizeable excretory pathway forsome essential trace elements. When young menwere exposed to 37.8#{176}Cfor 7.5 h daily for manydays and their sweat analyzed, calculations re-vealed that of the total dietary intakes, 59% ofthe chromium, 45% of the copper, 42% of the zinc,41% of the molybdenum, 106% of the strontium,and 520% of the selenium were excreted daily (30).Excretions of manganese and iron were small;11% of cobalt and 16% of iodine in the diet ap-peared in sweat. Others have found that sweatcontains as much as 1.15 mg zinc and 1.0 mg iron/liter (39). In hot climates when 2-11 liters of sweatcan be excreted per day, excretion of zinc canexceed intake.

Excretion of trace elements in hair is negligible.Hair grows at an estimated rate of 150 mg/day.Zinc and iron are the only essential trace elements

Table 9. Normal Concentrations of ToxicAbnormal Trace Elements in Plasma and Urine”

Plasma, Urine,Element pg/iOO ml pg/I Method

Cadmium <10 12 44 SP, AA’Lead 4.6 36 CO, SPMercury 0.3 10 COAntimony 5.4 <0.05 NAATin 3.3 0.017 COArsenic 19.0 170 COBarium 7.9 0.017 SPBeryllium <0.4 1.1 COLithium 3.1 570 Fl

Data from Schroeder et al. (10, 16, 19, 20, 22,23, and in prepa.ration), Tipton et al. (28, 29), and Bowen (1).

See footnote to Table 8.

in appreciable concentration in hair; the othersare found in low concentrations (Table 4). Levelsprobably reflect intakes and exposures duringgrowth of hair, and are thus only indirectly relatedto bodily contents. Low levels of chromium havebeen found in the hair of juvenile diabetics. Man-ganese levels are low in white hair. Hair from f e-males had more magnesium, copper, nickel, andzinc than did hair from males. Levels of copper inhair from females declined with age. There was lesszinc in blond hair than in brown or red hair (24).

Red hair has been reported to contain much iron.Tissue concentrations of some elements change

with age in American subjects (40). Significant in-creases in aortic concentrations were found forcalcium, magnesium, and phosphorus. In liver,copper, manganese, and molybdenum decreasedwith age. In bone, calcium, magnesium, and man-ganese declined. In kidney and testes, calcium in-creased with age. Whether or not these changesreflect the aging process is not known. Likewise,chromium increased in lung, probably from air-borne insoluble particulates. Total serum coppersteadily increased with age from 29 to 69 years(41), from 124 to 145 /.Lg/100 ml (P <0.OD1), whichwas not reflected by changes in other tissues exceptbrain.

Abnormal Trace Elements

There are at least 17 abnormal or nonessentialtrace elements found in the body of man in ap-preciable quantities. Nine are toxic either overtlyor innately (Table 5), whereas life term studies offeeding small amounts, or other toxicity studies,have shown eight to be more or less inert biologi-cally at the doses commonly encountered. Expectedamounts in blood and urine are shown in Table9.

The problem with the abnormal trace elementsis not deficiency-for life can apparently exist with-


out them-but excess, and especially accumulationin tissues with age. There are three natural “con-taminants” in soil and dust that accumulate in thehuman lung: aluminum, titanium, and barium.These are inert. There are three largely man-madecontaminants that accumulate in lung with age:chromium, as mentioned previously, tin from coal,and vanadium from petroleum. These all comefrom polluted air and are probably inert in lung.There are eight elements found in man and occur-ring naturally in food, water, and in some cases air:rubidium, bromine, zirconium, niobium, lithium,boron (essential for all plants), arsenic, and mer-cury. They fulfill no known biological function,and are probably inert at “normal” concentrations.

The elements that should concern us in relationto human disorders are those accumulative onesordinarily present in small concentrations in theenvironment, hut which man has mined and usedin a variety of ways to increase human exposures,sometimes beyond tolerance levels. These arecadmium, lead, methyl mercury, tin, antimony,arsenic, beryllium. To plants and fungi, the orderof toxicity is Be, Hg, Sn, Ph > As, Sb, Cd, B >Ba. To mammals, orally, the order of acute toxic-ity is As> Cd, Hg, Pb, Sb, Be> Sn, and Ba (1).To rats and mice fed low doses for life in our lab-oratory the order of toxicity was: methyl Hg >Ph > Cd > Sb > Sn > Be > Ba > As.

In low doses, certain trace elements increase theincidence of spontaneous tumors and malignanttumors in rats and mice: selenate (rats and mice),selenite (very toxic in rats, carcinogenic in mice),tellurite and tellurate (mice), rhodium and pal-ladium (mice), and yttrium (mice). Germaniumpartly suppressed tumors. Tumors were not af-fected by scandium, titanium, vanadium, chro-mium (III), chromium (VI), nickel, gallium,arsenic, fluorine, zirconium, niobium, molybdenumcadmium, indium, tin, antimony, and lead. Thesecarcinogenic elements offer little environmentalhazard to human health at the present time.

Cadmium. Environmental cadmium providesthe most insidious and most widespread healthhazard of any of the trace elements (10, 19, 42).Accumulating in kidney and liver with age (means10 and 4mg, respectively), and probably in arterialwall, it induces arterial hypertension. The diseasehas been duplicated in rats fed small doses, withmoderate arteriolar sclerosis in kidney, heart, andother areas (43). Cadmium displaces zinc in tissues,especially in kidney. There, ligands appear to havea higher affinity for cadmium than for zinc, so thatcadmium accumulates at the expense of zinc, upto 17-25 mg in kidney, and 50-100 mg in the body.

Most synthetic chelating agents have a strongeraffinity for zinc than for cadmium. A few, however,in that they have the reverse affinities, behave likethe kidney and blood vessels. When one of these,cyclohexanediaminotetraacetic acid, is complexed

to zinc and injected into rats made hypertensivewith cadmium, it binds cadmium in exchangefor zinc, removes it, and so cures the hyper-tension. This agent, NaZn CDTA, thus restoresthe normal ratio of cadmium to zinc, part probablybeing excreted in the urine as NaCd CDTA. It isunder clinical trial at present; results are generallyfavorable.

Basal blood pressure of rats is proportional tothe intake of cadmium (44). Death rates fromhypertensive heart disease are closely correlatedwith cadmium in air and milk (10). Air providessmall amounts of cadmium, which are completelyabsorbed from lung. Soft acidic waters dissolvecadmium from pipes, to the extent that the tapwater of one hospital does not fulfill Public Healthstandards for potable water, nor do many othertap waters (10). Absorption of cadmium in fooddepends in part on the concomitant level of zinc.Ratios of zinc to cadmium in various foods are:sea foods, 22: 1, meats 35: 1, cereals and grains110:1, vegetables 13-350:1, oils and fats 11:1,nuts 680: 1, fruits 13: 1, and beverages 12: 1.

Hypertensive patients excrete many times asmuch cadmium in their urine as do normotensivesubjects (42). Because hypertension is secondaryto a number of conditions, patients exhibiting thisfinding should have their urines analyzed forcadmium and zinc, to detect possible cadmiumhypertension, which may be amenable to specifictherapy. Furthermore, the renal cortex can beanalyzed at necropsy, because the ratio of cadmiumto zinc has been found to be enhanced in hyper-tensive kidneys (42).

Lead. Environmental lead is a potential hazardto human health (23). Although lead is ubiquitouson the earth’s crust at 10 ,g/g, and is present in allliving organisms, it is exhausted into the environ-ment, mainly from motor vehicles burning leadedgas (alkyl lead), at a rate of 1 kg/capita annually.Only about 10% of ingested lead is absorbed by thebody, but about 50% of inspired lead is absorbedfrom lung. The practice of leading gasoline to in-crease performance of high compression engines hasresulted in human body burdens of 120-480 mg oflead, and the interval between overt lead poisoningand no overt symptoms is narrowing in manyurban dwellers.

There is a strong suspicion that subclinical leadtoxicity short of the usual signs of lead poisoningexists as an entity (23). Lead accumulates in manyhuman tissues with age, although about #{182}2%ofthe lead in the body is in bone. Bone lead can bepartly mobilized during physical stress, just ascalcium is mobilized. In prolonged bed-rest it ispossible that lead moves from bone with calcium.A few patients with ill-defined symptoms of fatigue,weakness, lethargy, and insomnia, usually diag-nosed as “neurosis,” have been found to excreterelatively large amounts of lead following injection


of NaCa EPTA, a chelating agent that binds lead.There may be many more.

Lead fed to mice and rats in low doses, to matchhuman tissue concentration, shortened life spanabout 20%, caused early mortality, and producedweight loss and poor appearance in the aged.Chromium deficiency enhanced lead toxicity.

A high “index of suspicion” in clinicians andclinical pathologists may reveal innate lead toxicityin urban dwellers who feel tired, “run down,”“below par” or “nervous,” if lead is measuredin blood and urine, and intravenous EDTA is usedto determine excessive lead in the urine.

A large amount of lead, 57-85% of the intake,can be excreted in sweat (30). It is not impossiblethat the sense of well-being resulting from saunabaths, steam baths, vigorous exercise, or exposureto the hot and low-lead environment of the tropicsis the result of negative lead balances induced bysweating. As much as 250 tg have been excreteddaily by sweating men, the calculated amountabsorbed from food being 30 g.

Evaluation of lead status involves measure-ments in blood, urine, and perhaps hair, which donot necessarily reflect the amount in bone. Only bymobilization from soft tissue can excesses he as-certained. Measurement of red cell a-amino-levulinate dehydratase (5-aminolevulinate hydro-lysase, EC 4.2.1.24) activity, abnormal at all con-centrations of lead encountered in blood (45), isa sensitive way to detect one abnormality resultingfrom exposure to environmental lead.

Mercury. Mercury is present in every livingthing on the earth (1). “Reference Man” contains13 mg, or nearly 0.2 g/g (27), for there is mercuryin food, water, and air. This mercury is nontoxic;acute and subacute toxicity results only from mas-sive exposures, for metallic inorganic and organicmercury does not accumulate in or remain in thebody for long, being excreted in urine, intestinalsecretions, and hair. Lack of cumulative toxicity isexemplified by the old treatment of syphilis bymercury to the point of salivation, diarrhea, anddiuresis, symptoms that rapidly subsided betweentreatments.

In certain local areas mercury has polluted thewaters by being dumped into discharges fromchloralkali plants, or from mercury fungicidesapplied to grain. Anaerobic bacteria in mudapparently methylate this mercury, which thenbecomes soluble in water and enters the food chain.The resulting methyl mercury is very toxic, beingsoluble in fat and nervous tissue. Fish may accumu-late it. Two outbreaks of serious and fatal methylmercury poisoning from eating fish contaminatedwith 5-40 jg of mercury per gram occurred inJapan some 10-20 years ago, as a result of dump-ing methyl mercury into rivers.

Just what proportion of methyl mercury is infish and other foods is unknown, for methods to

distinguish between the two forms are not readilyavailable in this country. In spite of this uncer-tainty, the Food and Drug Administration has seta limit of 0.5 .ig/g for total mercury in fish; thislimit is based on the amount least detectable byolder colorimetric methods, and the aim of theFDA has been zero levels, a goal impossible toachieve on this planet.

This limit is illogical and unrealistic, and has ledto erroneous conclusions. A limit of 0.5 ig of methylmercury per gram is probably realistic, but one of0.5 tg of natural or nonalkyl mercury per gram ismisleading. For example, “Reference Man” hasthe following “excessive” or “dangerous” concen-trations (in .tg/g): hair, 6; kidney, 2.8; brain, 1.0;and lung, 0.58 (27). Shales have 0.4 g of mercuryper gram; soils, 0.03-0.8; mollusk shells, 3.0, andmollusk flesh, 1.6 (1). Background concentrationsof pelagic fish are 0.3 g/g (range, 0.1-0.7 jg/g).Fish eaters have more than non-fish eaters.

No one knows the background or normal levelsof mercury in fresh water fish, Middle Westernpheasants, Maine woodcock, Alaskan fur seals,swordfish, and tuna, which have been assumed tobe “contaminated” by polluted waters and grains.As more and more fish, birds, and mammals arefound to contain mercury, the false assumptionwill be made that man has polluted the whole earthwith mined mercury. But there has been mercuryin fish ever since there were fish, and older andlarger fish probably accumulate it with age. It isinconceivable that the oceans have been so pollutedwith methyl mercury that tuna fish is unsafe toeat. Fresh water contains 0.08 to 1.0 ng of mer-cury per ml, and sea water 0.03 ng/ml (1), enoughto “contaminate” fish, considering the enormousvolumes of water that pass through their gills andthe chemical affinities of mercury for proteins.One can predict that oysters will be soon declaredunsafe, if this guideline is used.

Measurement of mercury requires special attach-ments to the atomic absorption apparatus. Atpresent, the clinical chemist will do well to avoidwasting his time measuring mercury, except incases of overt poisoning, or for his own academicinterest, and wait until logic, reason, and commonsense abate the present furor. In the interim,methyl mercury compounds should be prohibited.

Accumulation. Of the abnormal trace elements,urinary excretion is 40% or more of the dietaryintake for mercury, antimony, tellurium, rubidium,bromine, niobium, titanium, lithium, and boron.Three are excreted as cations, the remaining six asanions. Urinary excretions are less than 10% of theintake for lead, beryllium, tin, barium, aluminum,zirconium; 14% for cadmium; and 20% for arsenic.All but arsenic are excreted as cations. Those thataccumulate in human or mammalian tissues are:cadmium in kidney, liver, and aorta; lead in bone,hair, aorta, liver, and kidney; mercury in kidney,


fat, and hair; beryllium in lung; barium in lung;tellurium in bone; tin in heart, intestine, and lung;arsenic in aorta, spleen, and hair; antimony in hair,bone, and liver; and aluminum and titanium inlung. The remaining six do not accumulate. Low-grade toxicity probably results from accumulationof excessive amounts.

Antagonisms. When an abnormal element hasthe same electrochemical properties and similaratomic structure as that of an essential element, itis biologically antagonistic, although its atomicweight is usually larger. In rare cases it stimulatesor alters function of the enzyme that depends onthe essential element; in most cases it depressesfunction. It is as if two keys fitted the same lock,but only one opens it.

Biological antagonisms have been demonstrated,either in vivo or in vitro, between niobium andvanadium, tungsten and molybdenum, silver andcopper, possibly gold and copper, cadmium andzinc, arsenic and phosphorus, selenium and sulfur,lithium and sodium, rubidium and potassium, andprobably barium and strontium. These respectivepairs belong to the same periodic group. In addi-tion, cross reactions have been shown for nickeland copper, copper and molybdenum, seleniumand cadmium, and arsenic and selenium.

Laboratory considerations. For practical pur-poses, the clinical pathologist, with the limitationsof his laboratory, will probably confine his intereststo the following abnormal trace elements: cad-mium and lead, for the purposes already discussed;lithium, to control therapeutic doses for hypomanicpsychoses; and arsenic, to diagnose arsenic poison-ing by analyses of tissues and hair. Arsenic requiresspecial equipment for analysis. He may beinterested in mercury if he works near heavilypolluted waters. The others-beryllium, tin, andantimony-require specialized techniques that arenot rewarding for use in a clinical laboratory.

Teratogenic effects have been observed for cer-tain trace elements when breeding mice and ratswere exposed to low doses in drinking water (46),and when pregnant hamsters were injected withsmall doses intravenously (47, 48). Most of theessential trace metals were not teratogenic. Cad-mium, lead, methyl mercury, selenate, nickel, andtitanium caused congenital abnormalities, smalllitters, deaths, and runts; arsenite was relativelynontoxic. Large doses of molybdate were alsoteratogenic. Whether or not such effects occur inhuman beings is not known, but subtle toxicity ofthis nature should he investigated.

When an element such as potassium, magne-sium, iron, zinc, copper, or manganese is largelycontained within cells, analyses of plasma or serumand urine do not necessarily reflect body contents.Concentration in cells, usually red blood cells, isoften a more reliable index of intracellular con-tents. When an element is mainly concentrated in

bone (e.g., fluorine, strontium, lead, barium, andberyllium) or in fat (e.g., vanadium, mercury, andzirconium), plasma or red cell concentrations andurinary concentrations may be unreliable for esti-mating total body burdens. In the case of theseelements, bone marrow and (in chronic states)hair may be helpful in evaluating status. Patho-logical specimens readily lend themselves to analy-ses by standard methods (42, 50).

New methods and modifications of oldermethods of analysis are continuously appearing.In some cases, they extend the limits of detectionof trace elements to values so extremely small thatthey are clinically and biologically meaningless.In terms of disease, optimal function, or innatetoxicity, it is extremely unlikely that a few pico-grams, nanograms, or even micrograms can exertmeasurable biological effects, except in rare cases,such as cobalt in vitamin B,2. Undoubtedly everynatural element in the Periodic Table, excepttechnetium, could be found in the human body ifsensitive-enough methods were made available.

An example of a method that extends detectionlimits of silver, gold, beryllium, calcium, cadmium,copper, iron, magnesium, lead, and zinc into thepicogram range is that of Amos et al. (51). By useof a hollow carbon rod heated to incandescence,through which argon gas is passed, and flamelessatomic fluorescence spectrometry, these elementscan be measured accurately in 0.5- to 2-gil samplesof solution. The need for very small samples andextreme sensitivity in clinical chemistry is not yetapparent, but it could become so for such tissuesas hepatic and renal needle biopsies, and suchfluids as spinal fluid, semen, and prostatic secre-tions.

Table 10 summarizes the various diseases andconditions in which analyses of trace elements inplasma, red blood cells, urine, and hair may beusef iii diagnostic aids. Also listed are several condi-tions that have their counterparts in experimentalanimals, and that deserve investigation from thisviewpoint.

Summary and conclusions. To present the need,present and future, for analysis of blood, urine, andtissues for trace elements as diagnostic and thera-peutic aids, we have summarized what is knownabout contents, concentration, and principal stor-age depots of 11 essential trace elements and 22nonessential or innately toxic trace elements. Thissubject is developing rapidly, and its importanceto the physician will expand during the next fewyears. Analytical techniques are not difficult, andanalysis of blood and urine for certain trace ele-ments will become routine for many diseases andconditions.

This work was supported by grants in aid from NIH, USPHS(grant HE 05076), General Foods Corp., Ciba PharmaceuticalCo., and the Cooper Laboratories, Inc.

Table 10. Diseases and Conditions in Which Analysis of Trace Elements May Be of Aid in Diagnosis, orDisclose Abnormalities

Disease or condition Deficiency present Excess present Remarks and treatment

Atherosclerosis Crb Replacelschemic symptoms Zn ReplaceIndolent ulcers Zn ReplaceMyocardial infarction Zn Mn, Ni, Cu Secondary in blood

Diabetes mellitus, juvenile Cr In hairmild, adult Cr Replace

Arterial hypertension Zn? Cd Chelation?Oral contraceptives Zn ReplacePregnancy Zn, Mn?, Cr, Cu? Replace

Toxemia Zn CdMalnutrition Cr, Mn, Cu, Zn, Mo ReplaceKwashiorkor Cr, Mn, Cu, Zn, Mo?Chronic alcoholism Zn, Mn ReplaceProlonged intravenous feeding Zn, Mn, Cu ReplacePostoperativeconvalescence Zn ReplaceSlow wound healing Zn ReplaceRenal insufficiency Zn ReplaceHypoproteinemia Cu In bloodExcessive proteinuria ZnCollagen diseasesDisseminated lupus Mn?Rheumatoid arthritis CuHydralazine disease Mn Replace

Idiopathic hemochromatosis Fe, Pb ChelationHepatolenticular degeneration Cu, Ag ChelationDietary(Bantu) siderosis Fe, Pb Chelation?Cirrhosisof liver, adult Zn Cu Replace Zn

juvenile Cu, AgSenile osteoporosis Sr ReplaceDental caries Sr, Mo? FMental retardation, juvenile Pb Chelation testIll-defined asthenia Pb Chelation testIll-defined neurosis Pb Chelation testParkinsonism Mn? Chelation testMilkman’s syndrome (itai itai disease) Cd ChelationCancer of lung Be Ni, Cr(VI) TissueTuberculosis, active Zn ReplaceChronic infections Zn ReplaceAllergic states Co?Cartilaginous malformations Mn?Renal (xanthine) calculi Mo

Data from Schroeder et al. c2-23), Halsted and Smith (31), and Henzel et al. (33).

Elements in italics are considered causal factors in the diseases.

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