the cross-section trichometer: a new device for … · the cross-section trichometer: a new device...

The Cross-Section Trichometer: A New Device for MeasuringHair Quantity, Hair Loss, and Hair Growth

BERNARD COHEN, MD�

BACKGROUND Office physicians are unable to measure hair quantity, hair loss, and hair growth in asimple and meaningful manner. One solution is to measure the cross-sectional area of a bundle of hairthat is growing within a premeasured cross-section of scalp.

OBJECTIVE The objective was to design a mechanical device that precisely measures the cross-sec-tional area of a bundle of hair and design a device that can precisely delineate an area of scalp. It wasassumed that density and diameter changes are evidenced by changes in the bundle cross-sectional areaand that growth and loss are the result of density and diameter changes. These assumptions wereconfirmed using various sized bundles of known diameter non-hair filaments.

MATERIALS AND METHODS Bundles of hair and surgical silk fibers were tested using a mechanicaldevice that compressed the bundle and measured its cross-sectional area. Balding patients were cat-egorized according to their observed severity of the loss. Bundles of their uncut hair from 4-cm2 scalpsites were measured and the values were compared to the patient’s category of hair loss severity.

RESULTS In patients with balding, there was a direct correlation between the bundle’s cross-sectionalarea and the observed severity of the loss. The cross-sectional area was expressed as square millimetersof hair per square centimeter of skin� 100 (mm2/cm2� 100) and named the trichometric index (TI). Usingsurgical silk fibers, there was a direct correlation between the bundle’s cross-sectional area and thenumber of filaments, the diameter of the filaments, and the dry weight of the filament bundle. Usingaggregates of cut human hair, there was a direct correlation between the cross-sectional area and the dryweight of the bundle.

CONCLUSION This prototype device shows promise as a diagnostic instrument for measuring changesin hair quantity (mass), hair diameter, and hair density, as evidenced by preliminary studies using silksutures, cut human hair, and patients with various degrees of balding. Formal clinical studies are need-ed. Although the device itself showed a high degree of precision, the accuracy and reproducibility of themeasurements can be compromised if the sampling method is not carefully performed using magni-fication. The device is intended for use on uncut hair that is more than 1 inch in length.

Dr. Cohen holds patents on the method and device described in this report and will receive royalties on thesales.

Hair loss affects 75% of men and 10% of

women, but office physicians are unable to

measure its parameters in a simple and meaningful

way. Precise instrumentation and methodologies

have been limited to research centers and industry

laboratories where clinical studies and drug evalua-

tions are performed. The office physician needs

a rapid, easy, and precise method for measuring a

patient’s clinical status.

Hair quantity is determined by measuring the hair’s

density (n/cm2) and diameter (mm). Hair loss and

hair growth result when there is a fluctuation in one

and/or the other. An ideal hair-measuring technology

should reflect the simultaneous influence of both

density and diameter. The present devices and

methods have advantages and limitations

(see Table 1).

In discussions of hair density and hair diameter, it is

helpful to draw the distinction between the termsF

shedding and thinning, since both result in hair loss.

In states of shedding, hairs with diameters of normal

size fall out. It is normal to shed about 50 to 100

& 2008 by the American Society for Dermatologic Surgery, Inc. � Published by Wiley Periodicals, Inc. �ISSN: 1076-0512 � Dermatol Surg 2008;34:900–911 � DOI: 10.1111/j.1524-4725.2008.34175.x

9 0 0

�Department of Dermatology and Cutaneous Surgery, University of Miami, Miller School of Medicine,Coral Gables, Florida

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C O H E N

hairs per day, but in pathologic states of effluvium

and alopecia areata, shedding can be quite profound.

Underlying skin becomes more and more visible as

the shedding progresses. The hair density analysis or

hair count will accurately reflect this disorder.

Hair thinning is a disorder characterized by the

gradual miniaturization in the length and diameter

of individual scalp hairs. Underlying skin becomes

more and more visible as the hairs become smaller

and smaller. Thinning affects an estimated 75% of

men, and although it occurs in 10% of healthy

women, it might indicate an endocrine abnormality

in a small group of those affected. Unlike shedding,

thinning is not diffuse in its distribution over the

entire scalp, but almost always appears in a pattern

that spares the posterior and sides of the lower scalp,

creating a familiar horse-shaped fringe that persists

in spite of the most advanced cases. Thinning will

eventuate in lowered density as the affected hairs

vanish.

Thinning, in its earliest stages, cannot be visualized

and is difficult to diagnose and quantify. Simple

density counts comparing the permanent occi-

pital fringe to an area of balding are of limited

value because the balding area has a mixed popula-

tion of normal-sized and miniaturized hairs (see

Figure 1).

The anatomic fluctuations of density and diameter

result in hair loss and growth, but it should be noted

that the changes in hair diameter are considerably

more influential than changes in hair density. Coarse

hair has a diameter of about 80 mm, average hair

about 70mm, and fine hair about 60 mm. Surpris-

ingly, an 80-mm hair has almost twice the mass of a

60-mm hair because it has approximately double the

cross-sectional area (3.14� r2 = cross-sectional area).

If two individuals have the same number of hairs, all

the same length, the one with coarse hair has almost

twice as much hair mass as the one with fine hair.

A 10% change in hair density will result in a 10%

change in hair quantity. A 10% change in diameter

will result in a 20% change in hair quantity. Because

hair length varies with style, it is not considered in

the calculation of hair quantity.

Objectives

The broad objective was to develop a technology for

measuring the quantity of hair in a defined area of

scalp. If the density and diameter of hair determines

its quantity, and the cross-sectional area of an

aggregate of hair reflects the range of densities and

diameters within that aggregate, then the cross-

sectional area of the aggregate reflects the quantity

of hair within the aggregate. Based on this theory, a

technology was designed to measure the cross-

sectional area of all the hairs in an aggregate of hair

from a premeasured area of scalp. This value could

be used to quantify the hair that is present and then,

by comparison, quantify the amount of hair that has

been lost or gained.

To measure the collective cross-sections of hair in the

premeasured area, the ideal method/device must first

capture the hairs and compress the loose aggregate

into a rectangular bundle, before the measurement is

performed. The device should always compress the

bundle with the same exact load, regardless of the

Figure 1. In hair loss due to balding or thinning, the hairshave a wide range of diameters. When a hair count isperformed, any hair with a diameter larger than 30 mm iscounted as one hair.

D E R M AT O L O G I C S U R G E RY9 0 2

T H E C R O S S - S E C T I O N T R I C H O M E T E R

hair sample size. The compressive force should com-

pletely compact the bundle, but not with a force so

excessive to damage the captured hair. The load

should be incrementally applied with mechanical

precision rather than casual hand-applied force. A

precise scientific instrument should be included to

measure the cross-sectional area of the compressed

and fully compacted bundle. It is preferable that no

hair is cut and no physician supervision or oversight

be required. The device should be of small size, sen-

sibly priced, widely available, easy to use, and capable

of generating results in a short period of time.

The Resultant Device and the Method

for Testing

A device/method that fulfilled the above objectives

was created. It was tested using silk filaments and

human hair to determine if changes in the cross-

sectional area were correlated to changes in

the hair density (n/cm2) and/or diameter (mm)

(see Tables 2–4).

The device is a self-contained mechanical unit with a

rectangular anodized aluminum body that is held in

the right hand like a hypodermic syringe (see Figure

2). Extending from one end of the body is a hook-

shaped arm, and from the other end of the body, a

spring-loaded shaft with a retainer cap. The hook

and the cap are at opposite ends of one contiguous

shaft. An electronic sensing unit with LED display is

externally mounted on the side of the housing and

attached internally to the shaft. When the cap at the

end of the shaft is pressed with the thumb, the hook

arm extends out of the body at the opposite end, and

its travel distance is displayed on the LED screen in

hundredths of a millimeter. When the thumb is re-

leased, the hook retracts back toward the body.

To measure the cross-sectional area of a hair sample,

the arm is extended and hooked around a bundle of

hair that has been gathered from a 2� 2-cm area of

scalp (see Figures 3–5). When the thumb is lifted, the

bundle of hair is captured in a 1� 4-mm chamber

created on the ledge of the metal housing through

which the hook passes. The number and diameter of

hairs in the captured bundle determine the height of

the hair within the chamber. When initially captured,

the bundle is slightly compressed and not yet com-

pacted.

The mid portion of the long shaft has a threaded

portion that passes through a large threaded knob at

the base of the body. When the knob is turned

clockwise on the shaft, it compresses a heavy internal

spring. As a result, the spring delivers a precise load

to the upper and lower surface of the captured

rectangular bundle and compacts it.

TABLE 2. Correlation between Silk Strand Diame-

ter and the Bundle Cross-section

3-0 4-0 5-0 6-0

Bundle Cross-

section (mm2)

Strands per bundle

80 3.81

60 20 3.63

40 40 3.07

20 60 2.70

80 2.36

60 20 2.14

40 40 2.03

20 60 1.65

80 1.37

60 20 1.26

40 40 1.09

20 60 0.82

80 0.66

Eighty-strand bundles of mixed-size suture material were measured.

TABLE 3. Correlation between Silk Strand Density and the Bundle Cross-section

No. of Strands 20 40 60 80 100 120 140 160

Cross-Section (mm2) .36 .75 1.17 1.58 1.93 2.36 2.75 3.14

Cross-section divided by No. of strands .018 .019 .020 .020 .019 .020 .020 .020

Twenty-strand bundles of 5-0 suture material were measured.

3 4 : 7 : J U LY 2 0 0 8 9 0 3

C O H E N

The device is engineered to deliver no more or less

than the same predetermined load each time it is

engaged, regardless of the bundle size. When the

internal spring is compressed exactly 1 cm, the height

of the compacted bundle in its rectangular capture

chamber is displayed as millimeters on the LED

screen. For an 800-hair sample (about average

for 4 cm2 of scalp), the normal range of values falls

between 3.00 mm (for fine hair about 60 mm) to

4.00 mm (for coarse hair about 80mm). The value

displayed on the screen is expressed as square

millimeters of bundle cross-section per 4 cm2 of scalp

surface. When divided by 4 and multiplied by 100,

the normal range of values conveniently falls

between 75 to 100 1 (fine to coarse hair). This

value has been arbitrarily named the trichometric

index (TI).

It should be noted that extensive testing was per-

formed using various sized chambers, compression

loads, and sample sizes before the optimal mechanics

of the device were determined. A load was chosen

that would compress the loose bundle to a point of

complete compactionFthe point beyond which no

further compaction would occur. When this load was

determined, sample hair bundles were microscopi-

cally examined to determine if fracture or visible

distortion of the hair had occurred. On the basis of

TABLE 4. Correlation between Silk Strand Weight

and Bundle Cross-section

Number of

Strands Grams

Cross-

section

(mm2)

Grams

Divided by

Cross-section

150 0.2754 2.74 0.101

148 0.2728 2.72 0.100

146 0.2705 2.71 0.100

144 0.2672 2.65 0.101

142 0.2647 2.62 0.101

140 0.2590 2.52 0.103

138 0.2565 2.48 0.103

Figure 2. The trichometer device is shown in its neutralposition. When the shaft is pressed using the thumb, a J-shaped hook extends from the body. The travel distance ofthe shaft within the body is displayed as millimeters on theLED screen.

Figure 3. A close-up view of the capture hook at the end ofthe shaft, in its extended position.

Figure 4. The skin is marked with a four- or eight-leggedmarking template moistened with waterproof ink.



this, an optimal and safe standard compression load

was chosen. A working prototype was then designed

to deliver that same optimal load regardless of the

height (or the amount) of hair in the chamber. A self-

braking mechanism was added to prevent the oper-

ator from overtightening the threaded knob and

exceeding the optimal load. The spring material

and its design were further refined to insure that

the compression spring was in the center of its path

from fully opened to fully compressed, i.e., in the

mid range of its spring constant curve. This was done

to minimize the imprecision that metal springs

typically display at both ends of their compression

curves.

Results of Testing

The device was intended to indirectly measure den-

sity and diameter by directly measuring the cross-

sectional area of all the hairs in a premeasured area

of scalp skin. Four tests were performed. The first

was designed to determine if the device could detect

and measure small changes in surgical silk diameter

(mm). A second test was designed to determine if the

device could detect and measure small changes in the

bundle densities of hair and surgical silk (n/cm2).

A third test was designed to determine if there was a

correlation between the weight of the bundle and

its cross-sectional area. A fourth test sought to

establish a correlation between the observed hair loss

severity and the TI (mm2 hair per cm2 scalp� 100).

Diameter measurements were performed using

strands of 3-0, 4-0, 5-0, and 6-0 nonsterile braided

surgical silk (Havel’s Inc., Cincinnati, OH). Each

material was hand-measured using an electronic

micrometer (L.S. Starrett Co., Athol, MA), and

strand diameters were found to vary within 15 to

20mm along their length. The average diameters

were 3-0 = 150 mm, 4-0 = 100 mm, 5-0 = 75 mm, and

6-0 = 50 mm. Thirteen mixed-size bundles, composed

of 80 strands each, were prepared. The bundles were

incrementally reduced in size by mixing large caliber

strands with smaller caliber strands. Each bundle

was then measured using the device. When the re-

sults were plotted, the cross-sectional area of each

bundle was reduced in a sequence that mirrored the

incremental reduction of suture caliber (see Table 2).

Density measurements were performed using the

same braided silk suture material. Bundles of 5-0

silk, the diameter of which is approximately 75mm

(equivalent to the diameter of average-sized hair),

were prepared. Eight bundles, containing 20 fila-

ments each, were prepared. First the device was used

to measure the cross-sectional area of one bundle.

The device was then opened and a second bundle

was added. A second measurement was made, the

device was then reopened, and a third bundle was

added, etc. Bundles were incrementally placed in the

device until they totaled 160 fibers. The results are

posted in the chart below (see Table 3). The cross-

sectional area of the bundle was increased in a se-

quence that mirrored the incremental increase of

filaments added. The ratio of the number of fila-

ments to the cross-sectional diameter remained con-

stant.

Weight measurements were performed using a

150-strand bundle of 5-0 surgical filaments to de-

termine if the weight and the cross-sectional area of

a bundle were directly correlated. The bundle was

weighed on an electronic analytic balance, and its

Figure 5. The device shown applied to an isolated bundle ofhair from a 2�2-cm area of scalp in the mid frontal area.

3 4 : 7 : J U LY 2 0 0 8 9 0 5

C O H E N

cross-sectional area was measured using the new

device. The measurements were performed in a lab-

oratory with no humidity control. Then two fila-

ments were cut from the bundle, the bundle was

reweighed, and its cross-section was remeasured.

This was repeated six times. The cross-sectional area

of the bundle was reduced in a sequence that mir-

rored the incremental reduction of bundle weight.

The ratio between the weight and the cross-section

remained constant (see Table 4).

Weight measurements were then performed using a

bundle of cut human hair to determine if the weight

and the cross-sectional area of a bundle were directly

proportional (see Table 5). The bundle contained an

aggregate of hairs (approximately 400) collected

from three different women, all of whom had un-

dergone hair coloring or permanents in the previous

3 months. The measurements were performed in a

laboratory with no humidity control. Hairs were

incrementally cut from the bundle, the bundle was

reweighed, and its cross-section was remeasured.

This was repeated eight times. The cross-sectional

area of the bundle was reduced in a sequence that

mirrored the incremental reduction of bundle

weight. The ratio between the weight and the cross-

section progressively increased over a period of

30 minutes. This was thought to be the result of

ambient moisture absorption during the time re-

quired to collect the data. With both silk filaments

and hair, the cross-sectional areas of the bundles

were reduced in a sequence that mirrored the incre-

mental reduction of bundle weight.

Twelve male patients, age 23 to 67 years with

balding, were examined without magnification. The

observed ratio of hair to skin in the vertex area of

each patient was estimated by an observer familiar

with the Hair Loss Severity Scale (HLSS) technique.

Each patient was placed into one of four categories:

minimal = much more hair than skin, mild = more

hair than skin, moderate = more skin than hair, and

severe = much more skin than hair (see Figure 6). The

hair within the 4� 4-cm center of the vertex area

was isolated and measured with the device and ex-

pressed as TIs (mm2 hair per cm2 skin� 100). The TI

and hair loss severity of each patient were charted to

determine if there was a correlation (see Table 6).

Collection of the Hair Sample

It was clear from the onset that the sampling method

would be quite influential in determining the sys-

tem’s total precision. A 2�2-cm square of hair-

TABLE 5. Correlation between Hair Weight and

Bundle Cross-section

Number of

Hairs Grams

Cross-

section

(mm2)

Grams

Divided by

Cross-section

X 0.5536 2.08 0.265

X minus 2 0.5528 2.04 0.271

X minus 4 0.5519 1.98 0.278

X minus 8 0.5511 1.95 0.284

X minus 10 0.5506 1.94 0.283

X minus 12 0.5494 1.92 0.286

X minus 14 0.5480 1.89 0.289

X minus 16 0.5467 1.87 0.292

X minus 20 0.5434 1.82 0.298

Hairs were cut from a bundle of approximately 600 hairs; the

bundle was reweighed, and its cross-section remeasured

Figure 6. The Hair Loss Severity Scale uses the visible ratioof hair to skin to quantify the hair within a localized area ofscalp.3 (A) minimal, (B) mild, (C) moderate, and (D) severe.



bearing scalp skin was chosen because it could be

easily handled without magnification and repre-

sented a somewhat generous sample (see Figures 4

and 5). On average, this area contained about 800

hairs in patients with no loss. The sampling precision

was important since fewer than 3 hairs would, for

example, change the cross-sectional value of the

bundle from 3.30 mm2 to 3.31 mm2. The collection

method was not formally tested for reproducibility

because there were simply too many different combs,

tapes, clips, magnifying devices, marking pens, tem-

plates, stencils, bundling contraptions, etc., to be

evaluated. A standardized method for isolating the

hair sample from the 4-cm2 area (and immobilizing

the adjacent hair) has not been formalized at the

time of this publication. It should be pointed out

that the 4–cm2 site may be the shape of a triangle,

rectangle, or hexagon and is not limited to a

2� 2-cm square.

Several other issues needed to be addressed. Should

the hair be wet or dry? It was easier to gather a

sample with precise margins on the 2�2-cm square

if the hair was wet. Wet hair measurements were

performed in a salon setting where each client almost

always presented to the operator immediately fol-

lowing a shampoo. Almost all the samples gathered

in the physician’s office were performed on dry hair.

In both situations, a fine-toothed comb, 2.5�

magnifying loupes, and a sharp wooden toothpick

were used. The easiest method of demarcating the

2� 2-cm area was marking dots with a four-legged

or eight-legged template moistened on a pad of wa-

terproof ink. Stencils with four and eight holes were

also used to place the dots on the scalp skin surface.

When wet hair was combed away from the 2� 2-cm

square of scalp, it remained immobilized and firmly

in place. When the sampling was performed on dry

hair, the peripheral hair required immobilization

with hair clips or gummed tape. Several methods of

demarcating the area, without placing any ink marks

on the skin, have since been developed and will be

the subject of a future report.

The second sampling issue to be addressed was re-

turning to precisely the same site for a subsequent

measurement. Typically, when industry standard hair

counts and hair weight measurements are performed,

dots are tattooed on the scalp to identify the previous

test site. Tattoos were performed on several patients,

although our goal was to design a method that

would not require a permanent tattoo. Initially we

used a quick and easy method of simply extending a

nonstretchable 4-mm tape from the junction of the

upper lip and nose columella, on to and over the tip

of the nose, then up the forehead and along the

midline of the scalp along which the hair was cleanly

parted. An ink dot was simultaneously placed on the

tape and the scalp. The tape was removed and the

distance between the two points on the tape was

measured with a ruler attached to a tabletop. How-

ever, vertical movement of nose tip caused a 5- to 7-

mm variation in the anterior to posterior dot

placement.

The movement from side to side was considered less

critical when returning to the exact same site because

the gradation of hair loss in a balding individual is

much greater along the sagittal axis than the coronal

axis. Several methods and devices that enable a re-

turn to precisely the same area, without skin mark-

ing, have since been developed and will be the

subject of a future report.

TABLE 6. Correlation between Observed Hair Loss

Severity and the TI (mm2 Hair per cm2 Scalp� 100)

in 12 Patients with Vertex Balding

Patient Severity Score TI

1 Minimal 47

2 Minimal 44

3 Minimal 44

4 Mild 36

5 Mild 33

6 Mild 33

7 Moderate 25

8 Moderate 28

9 Moderate 26

10 Severe 22

11 Severe 20

12 Severe 21

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C O H E N

It is important to note that the sampled hair must be

a minimum of 1 inch (2.5 cm) in length at time of

testing. If not, the distance between the scalp surface,

the hook/anvil will be too small; and the hair might

be painfully tugged when the device is fully engaged.

Furthermore, if one anticipates newly emerging

hairs, be aware that the new hairs might not be of

sufficient length for capture. If the hair is too short,

the testing should be postponed until it has grown to

adequate length. If a clinical trial is being performed,

one should consider the time frame for anticipated

emergence of new hairs and their rate of growth.

Dates for retesting should be appropriately planned.

At first we assumed that the quantity of hair in

normal individuals was evenly distributed over the

entire scalp. We also assumed that in women with

telogen effluvium, diffuse hair loss, or sheddingF

the loss was evenly distributed over the entire surface

of the scalp. During the pilot studies, it was clear

that neither of these assumptions were correct.

A significant number of patients with no complaints

of hair loss had values higher on the top of the head

than in the occipital region. The same unexpected

distribution pattern was seen in women with com-

plaints of excessive shedding. Further search of the

literature revealed that the hair density changes

dramatically with age and that density is in fact

unequally distributed over the scalp, often highest on

the top of the head.10,11 These observations are sig-

nificant if one compares the occipital and midscalp

values when attempting to distinguish between

diffuse and pattern loss in women with complaints of

hair loss.

Conclusions and Discussion

The method/device described in this report is a me-

chanical refinement of the author’s previous pub-

lished HLSS.3 When using the HLSS, the observer is

asked to determine the ratio of grossly visible hair to

grossly visible skin. A series of photographs give

examples of the categories to be chosen. The

trichometer device/method described in this report

likewise compares the ratio of hair to skin, but uses

direct mechanical measurement of the hair and skin

cross-sections instead of imprecise visual determi-

nation. The HLSS method was used to determine the

correlation between hair loss severity and bundle

cross-sectional area (see Table 6 and Figure 6).

The notion of using an instrument to measure the

cross-sectional ratio of hair to skin, for the purpose

of measuring the quantity of hair, has been previ-

ously described. To the best of our knowledge, it was

first described in a 1936 patent by Nessler,12 who

designed a rudimentary device with a rectangular

slot for capturing hair and then hand-compressed the

hair with a blunt, guillotine-like anvil. The height of

the hair in the slot was measured using ruler-like

markings engraved on the side of the brass hand-held

device. The Nessler device appears to have never

gained popularity and no references could be found

in the medical literature.

In 2001, Arnold13 formally presented a method for

measuring the quantity of hair in a premeasured area

of scalp. Although the work was not published, Ar-

nold deserves full credit for introducing the concept

of measuring hair quantity using hair/skin cross-

sectional ratio to the hair science community. Ar-

nold’s work served as the inspiration for the method/

device described in this report.

Arnold isolated the hair from a premeasured area of

scalp, but he chose to measure the hair bundle using

a thread wrapped snugly around the bundle’s pe-

riphery. An ink mark was made on the circumfe-

rentially applied loop of thread at the point where

the strand crossed over itself. The thread was then

removed and stretched out, and the distance between

the two marks was measured. Arnold had measured

the circumference of the bundle and called this value

the hair mass index. Neidel and Bretschneider14 have

described and published the details of Arnold’s hair

mass measurement technique.

Nessler and Arnold did not standardize the load

applied to the bundle or control its application with

a mechanical apparatus. Because the bundle of hair



is soft and quite compressible, the variability of their

load and their method of application introduced

significant imprecision. Nessler’s ruler and Arnold’s

measuring thread technique were significantly im-

precise as well. The methods of Nessler, Arnold,

Hamilton-Norwood, Ludwig, and Cohen (HLSS) are

all imprecise and not suitable for scientific studies,

and although hair weight measurement, global pho-

tography, and hair counts are precise, and suitable

for scientific studies, they too have the following

limitations as mentioned in Table 1.

Global photography requires special equipment and

hairstyle conformity. It is designed to compare the

relative difference between the before and after ap-

pearance of a single patient. It does not generate a

single quantitative value for a localized area of the

scalp. Hair counts on the other hand do generate a

single quantitative value but the value does not re-

flect the wide variation of diameters seen in condi-

tions of thinning, i.e., androgenetic alopecia. Hair

weight measurement, the gold standard, is simply

too difficult and time-consuming to perform as an

office procedure, and hair weight, hair counts, and

Trichoscan all require that hair be cut. The tricho-

meter technology overcomes many of these limita-

tions and generates a value that simultaneously

reflects the influence of density and diameter alone.

Preliminary study results, using both silk fibers and

hair, were the same. The incremental changes in the

filament number, filament diameter, and bundle

weight were reflected as equal and proportionate in-

cremental changes in the bundle cross-sectional area.

It was concluded that the device could be used as a

reliable substitute for every instrument and method

that is presently used to measure the parameters of

hair loss and growth, including the dry hair weight

measurementFthe industry gold standard.

Although the device itself showed a high degree of

precision, it should be emphasized that the accuracy

and reproducibility of the measurements can be

compromised if the sampling method is not carefully

performed using magnification. Returning to the

same area for retesting without using a tattoo com-

promises the measurements as well. Both of these

issues will be the subject of a subsequent report.

The general availability of a simple hair-measuring

technology introduces a number of possibilities (see

Table 7). Any clinical condition characterized by

shedding and/or thinning could be informally quan-

tified and tracked. A patient’s hair growth response

to minoxidil, finasteride, and iron supplement could

be easily measured. The efficacy of popular modal-

ities like low-intensity laser, biotin, and saw pal-

metto could be informally determined by practicing

physicians. Unsubstantiated anecdotes could be

challenged, and hair growth scams revealed.

Hundreds of common drugs, prescription and over

the counter, are known to cause hair loss. These

include retinoids, anticoagulants, cholesterol-lower-

ing agents, anticonvulsants, antidepressants, gastric

TABLE 7. Possible Applications of the Trich-

ometer Technology

1. Quantify hair mass in a localized area of

thinning and/or shedding

2. Quantify the efficacy of proven and unproven

hair growth products and devices

3. Quantify the medical treatment response in

thyroid disease, iron deficiency, etc.

4. Quantify the results of hair transplantation

surgery

5. Quantify the donor hair available for hair

transplantation surgery15

6. Detect the reversal and recovery from post

partum effluvium

7. Detect balding before it is visible

8. Determine a new drug’s potential for causing

hair loss

9. Determine the incidence of hair loss caused by

FDA-approved drugs

10. Provide a simple 1–100 scoring system for hair

loss

11. Provide a new measuring modality for hair

science research

12. Enable the office physician to track and mea-

sure a patient’s clinical status

13. Improve and simplify communication between

hair professionals

FDA, Food and Drug Administration.

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C O H E N

acidity suppressants, cardiac arrhythmia and anti-

hypertensive agents, anti-inflammatory agents, hor-

mones, and weight reduction drugs . . . plus the

entire category of antineoplastic agents. Patients

taking these drugs could be evaluated to determine

the incidence and magnitude of their hair loss. New

drugs could be screened, before FDA approval, to

determine if they have the potential side effect of

causing hair loss.

Marritt observed that a man must lose 50% of his

hair mass before the loss can be seen with the naked

eye.16 This was confirmed in Table 6. The TI’s of

men with minimal hair loss were about 50% lower

than the TI’s of men with no loss at all. (Normal

range for TI is 75 to 100 plus.) Logically, the

trichometer might be used to identify men in very

early stages of balding, when diameter reduction

silently precedes visible loss. By measuring and

comparing the frontal and occipital regions of men

with normal-appearing hair, a loss as small as 5 or

10% could be detected y perhaps 10 or 15 years

before balding was actually visible. The speed of

progression and response to treatment could be

easily monitored.

References

1. Hamilton JB. Patterned loss of hair in men; types and incidence.

Ann NY Acad Sci 1951;53:708–28.

2. Norwood OT. Male pattern baldness: classification and incidence.

South Med J 1975;68:1359–65.

3. Cohen BH. Hair loss profile, index, and severity scale. In: Haber

R, Stough D, editors. Hair Transplantation. Philadelphia: Elsevier;

2006. p. 12.

4. Canfield D. Photographic documentation of hair growth in

androgenetic alopecia. Dermatol Clin 1996;14:713–21.

5. Price VH, Menefee E, Strauss PC. Changes in hair weight and

hair count in men with androgenetic alopecia, after application

of 5% and 2% topical minoxidil, placebo, or no treatment.

J Am Acad Dermatol 1999;11:41.

6. Van Neste D, Dumrotier M, De Coster W. Phototrichogram

analysis: technical aspects and problems in relation with

automated quantitative evaluation of hair growth by computer-

assisted image analysis. In: Van Neste D, Lachapelle JM, Antoine

JL, editors. Trends in human hair growth and alopecia research.

Dordrecht: Kluwer (Amsterdam); 1989. p. 155–65.

7. Hoffman R. TrichoScan: combining epiluminescence microscopy

with digital image analysis for the measurement of hair growth.

Eur J Dermatol 2001;11:362–8.

8. Headington J. Transverse microscopic anatomy of the human

scalp: a basis for a morphometric approach to disorders of the hair

follicle. Arch Dermatol 1984;120:449–56.

9. Barth JH, Rushton DH. Measurement of hair growth. In: Serud J,

Jemec G, editors. Non-invasive methods and the skin. Ann Arbor:

CRP Press; 1995. p. 543–8.

10. Olsen EA, Canfield D. Age-related changes in scalp hair density.

Tokyo: European Hair Research Society; 2001.

11. Van Neste D. Female patients complaining about hair loss:

documentation of defective scalp hair dynamics with contrast-

enhanced phototrichogram. Skin Res Technol 2006;5:83–8.

12. Nessler C. Means for ascertaining the hair production of a

subject. US Patent 1,962,518, United States Patent Office, June

12, 1934.

13. Arnold J. Hair mass index, 4th Annual Congress European

Society of Hair Restoration Surgery. Barcelona, 2001.

14. Neidel FG, Bretschneider P. Measuring hair mass. In: Unger W,

Shapiro R, editors. Hair Transplantation. New York: Marcel

Dekker; 2004. p. 876.

15. Parsley W. Donor site measurement. In: Haber R, Stough D,

editors. Hair Transplantation. Philadelphia: Elsevier; 2006.

p. 101.

16. Marritt E. The death of the density debate. Dermatol Surg

1999;5:654–60.

Address correspondence and reprint requests to: BernardCohen, MD, 4425 Ponce de Leon Boulevard, Suite 230,Coral Gables, FL 33145, or e-mail: [email protected]

COMMENTARY

The current standards for measuring hair loss and hair growth are laden with problems and inefficiencies.

The ongoing search for a simple and accurate method of measuring hair quantity has finally found respite

in a novel device recently christened the cross-section trichometer. This device, developed by Dr. Bernie

Cohen, is featured in this issue of Dermatologic Surgery. As Dr. Cohen has quoted many times, ‘‘Medicine

is a language of numbers. Simple numbers are used to make a diagnosis like hypertension, diabetes, fever,



and obesity. In fact, it’s the manipulation of these numbers that determines the manner by which we treat

these disorders. In simple terms, if it can’t be measured, it can’t be managed.’’

The challenge when evaluating all hair growth drugs is obtaining consistent methodology for measure-

ment. In the past, global photography has been utilized to document the overall change in the appearance

of hair from a baseline setting. Using serial global photographs, subjects were classified into distinct

categories, i.e., (1) greatly decreased in appearance, (2) slight decrease in appearance, (3) no change in

appearance, (4) slight increase in appearance, (5) moderate increase in appearance, and (6) great increase

in appearance. Unfortunately, the results are influenced by the F-stop settings on the camera.

Additionally, the lighting, film quality, grooming practices, and length of hair must be kept identical to the

original baseline photography or an erroneous change of appearance results. Keeping all of the above

factors constant is daunting and often not feasible. Global photography is a very crude and often in-

accurate method of assessing hair quantity in terms of both loss and growth. Global photography cannot

properly reflect changes in hair counts. To assess changes in hair counts, microphotographic techniques

are utilized. These techniques involve computer overlay in comparison to baseline photographs. The

addition of or loss of hairs is determined by a numerical value generated by the computer when comparing

photographs. This seems to be a more precise method, but fails to account for the changes in hair shaft

diameter, which often show the visible results.

Since the positive effect of minoxidil and 5a-reductase inhibitors (finasteride and dutasteride) use is in part

due to changes in hair shaft; the hair counts may be minimally affected. In other words, a positive effect

may be observed in a study patient by global photography with no change over baseline in actual hair

count. It is obvious from the above that our current methods are inadequate in providing a precise change

in hair mass. Dr. Cohen’s device offers a solution. When it is applied to a bundle of hair, any change in

density and diameter will be evident and measured numerically.

The article presented herein by Dr. Cohen is well written and deserves the attention of those involved in

hair research, clinical evaluations of hair disorders, and practicing hair transplant surgeons. It is not

unreasonable to project that at some point in the future residents in dermatology will utilize a device such

as the cross-section trichometer to routinely evaluate the success or failure of hair loss treatments in their

clinical patients. Practitioners look forward to this device being available to use on their patients. It will be

important for clinicians to produce the same, reproducible accurate results as presented in this article.

Dr. Cohen is to be applauded for both his success in bringing this to the field and his contributions in

advancing hair research.

DOW STOUGH, MD

Hot Springs, AR

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