fundamentals fluid electrolyte balance

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FUNDAMENTALS OF FUNDAMENTALS OF FLUID AND FLUID AND ELECTROLYTE BALANCE ELECTROLYTE BALANCE

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Page 1: Fundamentals Fluid Electrolyte Balance

FUNDAMENTALS OF FUNDAMENTALS OF FLUID AND FLUID AND

ELECTROLYTE BALANCEELECTROLYTE BALANCE

Page 2: Fundamentals Fluid Electrolyte Balance
Page 3: Fundamentals Fluid Electrolyte Balance

FLUID REQUIREMENTSFLUID REQUIREMENTS

SourcesSources LossesLosses

WaterWater 1500 ml1500 ml UrineUrine 1500 ml1500 ml

FoodFood 800 ml800 ml StoolStool 200 ml200 ml

OxidationOxidation 300 ml300 ml SkinSkin 500 ml500 ml

Resp. TractResp. Tract 400 ml400 ml

TotalTotal 2600 ml2600 ml TotalTotal 2600 ml2600 ml

Page 4: Fundamentals Fluid Electrolyte Balance

FLUID CONTENT OF THE BODYFLUID CONTENT OF THE BODY

Varies with age, sex, adipose tissueVaries with age, sex, adipose tissue Females 45-50% TBWFemales 45-50% TBW MalesMales 50-60% TBW 50-60% TBW Infants 77% TBWInfants 77% TBW

Page 5: Fundamentals Fluid Electrolyte Balance

BODY FLUID COMPARTMENTSBODY FLUID COMPARTMENTS

RULE OF THIRDSRULE OF THIRDS1.1. Intracellular: 2/3 Intracellular: 2/3 (40% TBW)(40% TBW)

2.2. Extracellular: 1/3 Extracellular: 1/3 (20% (20% TBW)TBW)

a.a. Interstitial + Lymph: 2/3 (15% TBW)Interstitial + Lymph: 2/3 (15% TBW)

b.b. Intravascular: 1/3 (5% TBW)Intravascular: 1/3 (5% TBW)

Page 6: Fundamentals Fluid Electrolyte Balance

Biomedical Importance of WaterBiomedical Importance of Water

Homeostasis (CES)Homeostasis (CES)• Water distributionWater distribution• PH maintenancePH maintenance• Maintain Electrolyte Concentration Maintain Electrolyte Concentration

Set of Fluid BalanceSet of Fluid Balance• Depletion (dehydration)Depletion (dehydration)• Intoxication (over-hydration) Intoxication (over-hydration) • Osmotic & non osmotic mechanismOsmotic & non osmotic mechanism

Page 7: Fundamentals Fluid Electrolyte Balance

Water as ideal biologic solventWater as ideal biologic solvent

Tetrahedron structureTetrahedron structure Bipolar moleculeBipolar molecule Multiple energyMultiple energy Hydrogen bond determines Hydrogen bond determines

macromolecule structuremacromolecule structure The best nucleofilThe best nucleofil Minor DissociationMinor Dissociation Electrostatic interactionElectrostatic interaction Interaction with biomoleculeInteraction with biomolecule

Page 8: Fundamentals Fluid Electrolyte Balance

ELECTROLYTES IN ELECTROLYTES IN BODY FLUID COMPARTMENTSBODY FLUID COMPARTMENTS

INTRACELLULARINTRACELLULAR EXTRACELLULAREXTRACELLULAR

POTASSIUMPOTASSIUM SODIUMSODIUM

MAGNESIUMMAGNESIUM CHLORIDECHLORIDE

PHOSPHOROUSPHOSPHOROUS BICARBONATEBICARBONATE

Page 9: Fundamentals Fluid Electrolyte Balance

IV FLUID DISTRIBUTION IN IV FLUID DISTRIBUTION IN BODY COMPARTMENTSBODY COMPARTMENTS

ICFICF ECFECF

Dextrose 5% in Dextrose 5% in Water Water

1000 ml1000 ml

2/32/3

667 ml667 ml1/31/3

333 ml333 ml

Sodium Chloride Sodium Chloride 0.9% 1000 ml0.9% 1000 ml 1000 ml1000 ml

Page 10: Fundamentals Fluid Electrolyte Balance

SOLUTESSOLUTES

Non-electrolytesNon-electrolytes• DextroseDextrose• UreaUrea• CreatinineCreatinine

ElectrolytesElectrolytes• AnionsAnions• CationsCations

Page 11: Fundamentals Fluid Electrolyte Balance

MAINTENANCE vs. REPLACEMENTMAINTENANCE vs. REPLACEMENT

Maintenance:Maintenance:• Provide normal daily requirements:Provide normal daily requirements:

Water: 2.5 LWater: 2.5 L

Sodium ½ or ¼ NSSodium ½ or ¼ NS

KCl 40-60 meq/LKCl 40-60 meq/L Example:Example:

D5 ½ NS with KCL 20 meq/L running at D5 ½ NS with KCL 20 meq/L running at 100 ml/hr100 ml/hr

Denis Wormington
Page 12: Fundamentals Fluid Electrolyte Balance

MAINTENANCE vs. REPLACEMENTMAINTENANCE vs. REPLACEMENT

Replacement:Replacement:• Replace abnormal losses with a fluid Replace abnormal losses with a fluid

and electrolytes similar to that which and electrolytes similar to that which was lost.was lost.

Page 13: Fundamentals Fluid Electrolyte Balance
Page 14: Fundamentals Fluid Electrolyte Balance
Page 15: Fundamentals Fluid Electrolyte Balance

OSMOLALITYOSMOLALITY

Definition: Concentration of particles (osmotically Definition: Concentration of particles (osmotically active) in solution. It is usually expressed in active) in solution. It is usually expressed in millosmoles of solute per kg of solution.millosmoles of solute per kg of solution.

Osmolality is independant of valence.Osmolality is independant of valence. Osmolality (mOsm/Kg) of dilute solutions Osmolality (mOsm/Kg) of dilute solutions

approximate osmolarity (mOsm/L)approximate osmolarity (mOsm/L) Plasma: 280-300 mOsm/KgPlasma: 280-300 mOsm/Kg Same in all body compartmentsSame in all body compartments Water distribution Water distribution

Page 16: Fundamentals Fluid Electrolyte Balance

Normal Laboratory ValuesNormal Laboratory Values

SodiumSodium 135-145 meq/L135-145 meq/LPotassium Potassium 3.5-5.0 meq/L3.5-5.0 meq/LChlorideChloride 95-105 meq/L95-105 meq/LBicarbonateBicarbonate 22-28 meq/L22-28 meq/LCalciumCalcium 9-11 mg/dL9-11 mg/dLPhosphatePhosphate 3.2-4.3 mg/dL3.2-4.3 mg/dLGlucoseGlucose 70-110 mg/dL70-110 mg/dLBUNBUN 8-18 mg/dL8-18 mg/dLCreatinineCreatinine 0.6-1.2 mg/dL0.6-1.2 mg/dLOsmolality (P)Osmolality (P) 280-295 mOsm/kg280-295 mOsm/kgOsmolality (U)Osmolality (U) 50-1200 mOsm/kg50-1200 mOsm/kg

Page 17: Fundamentals Fluid Electrolyte Balance
Page 18: Fundamentals Fluid Electrolyte Balance
Page 19: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSSODIUMSODIUM

JO is a 58 year-old male with cirrhosis of JO is a 58 year-old male with cirrhosis of the liver due to ethanol abuse. Physical the liver due to ethanol abuse. Physical examination reveal ascites. examination reveal ascites.

Baseline lab is as follows:Baseline lab is as follows:

Na 128, K 3.8, Cl 95, CO2 24Na 128, K 3.8, Cl 95, CO2 24

JO is to be started on TPN, Should we JO is to be started on TPN, Should we request additional sodium to correct his request additional sodium to correct his hyponatremia?hyponatremia?

Page 20: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSSODIUMSODIUM

Primary extracellular cationPrimary extracellular cation HyponatremiaHyponatremia

1.1. Excess of TB waterExcess of TB water

2.2. Decrease in TB sodiumDecrease in TB sodium

a.a. Isotonic hyponatremia (factitious)Isotonic hyponatremia (factitious)

b.b. Hypertonic hyponatremia (dilutional)Hypertonic hyponatremia (dilutional)

Page 21: Fundamentals Fluid Electrolyte Balance

ELECTROLYTE DISORDERSELECTROLYTE DISORDERSHypotonic HyponatremiaHypotonic Hyponatremia

Increased ECVIncreased ECV Decreased ECVDecreased ECV Normal ECVNormal ECV

Edematous statesEdematous states Hypovolemic statesHypovolemic states SIADHSIADH

CHFCHF

CirrhosisCirrhosis

Renal dzRenal dz

Diuretic inducedDiuretic induced

GI lossesGI lossesSydrome of Sydrome of inappropriate inappropriate antidiuretic hormoneantidiuretic hormone

Excess of TB Na and Excess of TB Na and waterwater

Depletion of water Depletion of water and Naand Na

Excess of water: Excess of water: dilutionaldilutional

Treatment:Treatment:

DiureticsDiuretics

Water & Na restrictionWater & Na restriction

CHF- cardiac CHF- cardiac glycosidesglycosides

Water and Na Water and Na replacementreplacement

Fluid restrictionFluid restriction

Furosemide and NSFurosemide and NS

Chronic: DeclomycinChronic: Declomycin

Page 22: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSSODIUMSODIUM

JO is a 58 year-old male with cirrhosis of the JO is a 58 year-old male with cirrhosis of the liver due to ethanol abuse. Physical liver due to ethanol abuse. Physical examination reveal ascites. examination reveal ascites. Baseline lab is as follows:Baseline lab is as follows:Na 128, K 3.8, Cl 95, CO2 24Na 128, K 3.8, Cl 95, CO2 24JO is to be started on TPN, Should we request JO is to be started on TPN, Should we request additional sodium to correct his hyponatremia?additional sodium to correct his hyponatremia?

JO’s is in an edematous state. He has an excess of JO’s is in an edematous state. He has an excess of TB water and sodium. The appropriate TB water and sodium. The appropriate treatment is water and sodium restriction. He treatment is water and sodium restriction. He should also receive diuretic treatment. The should also receive diuretic treatment. The drug of choice is Aldactone (spironolactone), an drug of choice is Aldactone (spironolactone), an aldosterone antagonist. aldosterone antagonist.

Page 23: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSModel for Distribution and Elimination of Model for Distribution and Elimination of

Intracellular IonsIntracellular Ions

K Phos Mg

ICF ECF

Intake

GI (stool)Losses

RenalLosses

StomachIntestine

Page 24: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Primary intacellular cationPrimary intacellular cation Hypokalemia: CausesHypokalemia: Causes

1.1. Decreased dietary intakeDecreased dietary intake

2.2. RedistributionRedistribution InsulinInsulin

Metabolic Alkalosis Metabolic Alkalosis

DehydrationDehydration

Page 25: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Metabolic Alkalosis and HypokalemiaMetabolic Alkalosis and Hypokalemia

Intracellular Fluid

H+

ExtracellularFluidK+

Page 26: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Primary intacellular cationPrimary intacellular cation Hypokalemia: CausesHypokalemia: Causes

3.3. Increased Urinary or GI LossesIncreased Urinary or GI Losses DiureticsDiuretics

NG SuctionNG Suction

DiarrheaDiarrhea

Page 27: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Hypokalemia: CausesHypokalemia: Causes

3.3. Increased Urinary or GI LossesIncreased Urinary or GI Losses NG SuctionNG Suction

DiarrheaDiarrhea

DrugsDrugs

Page 28: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Drugs which may cause hypokalemiaDrugs which may cause hypokalemia

Urinary wasting: aminoglycosides, Urinary wasting: aminoglycosides, amphotericin B, corticosteroids, diuretics, amphotericin B, corticosteroids, diuretics, levodopa, nifedipine, penicillins, rifampinlevodopa, nifedipine, penicillins, rifampin

Gastrointestinal losses: laxativesGastrointestinal losses: laxatives

Redistribution: Beta-2 agonists, lithiumRedistribution: Beta-2 agonists, lithium

Page 29: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Hypokalemia: Treatment/Estimation of Hypokalemia: Treatment/Estimation of DeficitDeficit

If serum K > 3meq/L: If serum K > 3meq/L:

100-200 meq required per each change in 100-200 meq required per each change in serum K of 1 meq/Lserum K of 1 meq/L

If serum K < 3 meq/L:If serum K < 3 meq/L:

200-400 meq required per each change in 200-400 meq required per each change in serum K of 1 meq/Lserum K of 1 meq/L

Page 30: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Hypokalemia: Estimation of DeficitHypokalemia: Estimation of Deficit

If serum K > 3meq/L: If serum K > 3meq/L:

100-200 meq required per each change in serum K of 1 meq/L100-200 meq required per each change in serum K of 1 meq/L

If serum K < 3 meq/L:If serum K < 3 meq/L:

200-400 meq required per each change in serum K of 1 meq/L200-400 meq required per each change in serum K of 1 meq/L

Example: Serum K = 2.5 How much K is required to correct serum K to Example: Serum K = 2.5 How much K is required to correct serum K to 4.0?4.0?

Step 1Step 1

To increase from 2.5 to 3.0: 200-400 meq X 0.5=100-200meqTo increase from 2.5 to 3.0: 200-400 meq X 0.5=100-200meq

Step 2Step 2

To increase from 3.0 to 4.0: 100-200 meq X 1.0=100-200meqToTo increase from 3.0 to 4.0: 100-200 meq X 1.0=100-200meqTo

Total=200-400meqTotal=200-400meq

Page 31: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUM POTASSIUM

Hypokalemia: TreatmentHypokalemia: Treatment

Serum KSerum K Max Max Infusion Infusion RateRate

Max.Max.

Conc.Conc.Max. Dose Max. Dose 24 hrs24 hrs

> 2.5meq/L> 2.5meq/L 10 meq/hr10 meq/hr 40 meq/L40 meq/L 200 meq200 meq

<2meq/L<2meq/L 40 meq/hr40 meq/hr 80 meq/L80 meq/L 400 meq400 meq

Page 32: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Mrs D. is a 62 year-old female who is having an Mrs D. is a 62 year-old female who is having an acute exacerbation of Crohn’s disease. She acute exacerbation of Crohn’s disease. She complains to you of severe and frequent complains to you of severe and frequent diarrhea over the last four days. She diarrhea over the last four days. She experiences dizziness when she stands. Your experiences dizziness when she stands. Your physical examination reveals dry mucous physical examination reveals dry mucous membranes. In the supine position her membranes. In the supine position her BP=110/65 and in the upright position her BP=110/65 and in the upright position her BP=90/45 and her pulse=140. Your lab values BP=90/45 and her pulse=140. Your lab values are as follows:are as follows:

Na 132, K 2.9, Cl 92, CONa 132, K 2.9, Cl 92, CO22 31, 31, BUN 25, Cr 1.0BUN 25, Cr 1.0

Discuss Mrs. D’s fluid and electrolyte problems.Discuss Mrs. D’s fluid and electrolyte problems.

Page 33: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSCase Study: HypokalemiaCase Study: Hypokalemia

Mrs D. is a 62 year-old female who is having an acute exacerbation of Mrs D. is a 62 year-old female who is having an acute exacerbation of Crohn’s disease. She complains to you of severe and frequent Crohn’s disease. She complains to you of severe and frequent diarrhea over the last four days. She experiences dizziness when diarrhea over the last four days. She experiences dizziness when she stands. Your physical examination reveals dry mucous she stands. Your physical examination reveals dry mucous membranes. In the supine position her BP=110/65 and in the membranes. In the supine position her BP=110/65 and in the upright position her BP=90/45 and her pulse=140. Your lab upright position her BP=90/45 and her pulse=140. Your lab values are as follows:values are as follows:

Na 132, K 2.9, Cl 92, CONa 132, K 2.9, Cl 92, CO22 31, 31, BUN 25, Cr 1.0BUN 25, Cr 1.0Mrs D’s has extracellular volume depletion due to prolonged diarrhea. Mrs D’s has extracellular volume depletion due to prolonged diarrhea.

The ECVD is supported by her physical assessment and postural The ECVD is supported by her physical assessment and postural hypotension and her BUN/Cr is > 20:1. The diarrhea has resulted hypotension and her BUN/Cr is > 20:1. The diarrhea has resulted in a loss of fluid and sodium chloride. Some potassium was lost in a loss of fluid and sodium chloride. Some potassium was lost directly in the stools, but the main cause of her hypokalemia is directly in the stools, but the main cause of her hypokalemia is her ECVD which has induced a metabolic alkalosis (contraction her ECVD which has induced a metabolic alkalosis (contraction alkalosis.) The alkalosis contributed to her hypokalemia by two alkalosis.) The alkalosis contributed to her hypokalemia by two mechanisms. Some potassium has moved to the intracellular mechanisms. Some potassium has moved to the intracellular compartment but much of it has been lost in the urine where compartment but much of it has been lost in the urine where potassium wasting occurs secondary to chloride deficit. potassium wasting occurs secondary to chloride deficit. Administration of Normal Saline with Potassium Chloride will Administration of Normal Saline with Potassium Chloride will correct her fluid and electrolyte problems (and alkalosis.)correct her fluid and electrolyte problems (and alkalosis.)

Page 34: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Hyperkalemia: CausesHyperkalemia: Causes

1.1. Decreased Renal ExcretionDecreased Renal Excretion CRF and ARFCRF and ARF

Drug induced: Drug induced:

K-sparing diuretics (spironolactone, K-sparing diuretics (spironolactone, triamterine, amiloride)triamterine, amiloride)

Angiotensin converting enzyme inhibitorsAngiotensin converting enzyme inhibitors

NSAIDSNSAIDS

Page 35: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Hyperkalemia: CausesHyperkalemia: Causes2.2. RedistributionRedistribution

Trauma, burnsTrauma, burns AcidosisAcidosis Hyperosmolar states Hyperosmolar states

3.3. Increased intakeIncreased intake Salt substitutesSalt substitutes Blood transfusionsBlood transfusions K salts of antibioticsK salts of antibiotics

Page 36: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Metabolic Acidosis and HyperkalemiaMetabolic Acidosis and Hyperkalemia

Intracellular Fluid

K+

ExtracellularFluidH+

Page 37: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPOTASSIUMPOTASSIUM

Hyperkalemia: TreatmentHyperkalemia: Treatment1.1. Potassium AntagonistPotassium Antagonist

Calcium ChlorideCalcium Chloride

2.2. RedistributionRedistributiona.a. Insulin + dextroseInsulin + dextroseb.b. Sodium bicarbonateSodium bicarbonate

3.3. Cationic binding resinsCationic binding resinsKayexalate (polystyrene sulfonate)Kayexalate (polystyrene sulfonate)

4.4. Renal Elimination/dialysisRenal Elimination/dialysis

Page 38: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSMAGNESIUMMAGNESIUM

Hypomagnesemia: CausesHypomagnesemia: Causes1.1. Decreased IntakeDecreased Intake

MalnutritionMalnutrition AlcoholismAlcoholism

2.2. Decreased AbsorptionDecreased Absorption3.3. Increased LossesIncreased Losses

GI lossesGI losses Renal lossesRenal losses

Page 39: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSMAGNESIUMMAGNESIUM

Drug Induced HypomagnesemiaDrug Induced Hypomagnesemia

1.1. GI LossesGI Losses LaxativesLaxatives

2.2. Renal LossesRenal Losses Diuretics, cisplatin, aminoglycosides, Diuretics, cisplatin, aminoglycosides,

amphotericin Bamphotericin B

Page 40: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSMAGNESIUMMAGNESIUM

Hypomagnesemia: TreatmentHypomagnesemia: Treatment

1.1. IV Magnesium SulfateIV Magnesium Sulfate Replace over several daysReplace over several days

Renal threshold for reabsorption of MgRenal threshold for reabsorption of Mg

1 mEq/kg on day 11 mEq/kg on day 1

0.5 mEq/kg on days x 3-5 days0.5 mEq/kg on days x 3-5 days

2.2. Oral replacementOral replacement MylantaMylanta

Page 41: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSMAGNESIUMMAGNESIUM

Hypermagnesemia: CausesHypermagnesemia: Causes1.1. Exogenous ingestionExogenous ingestion

2.2. Impaired renal excretionImpaired renal excretion

Treatment: Eliminate exogenous Treatment: Eliminate exogenous source of Mgsource of Mg

Page 42: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPHOSPHOROUSPHOSPHOROUS

Hypophosphatmeia: CausesHypophosphatmeia: Causes1.1. Impaired absorptionImpaired absorption

Aluminum or calcium bindingAluminum or calcium binding

2.2. RedistributionRedistribution Respiratory alkalosisRespiratory alkalosis

Glucose + insulinGlucose + insulin

3.3. Increased ExcretionIncreased Excretion

Page 43: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPHOSPHOROUSPHOSPHOROUS

Hyperphosphatmeia: CausesHyperphosphatmeia: Causes1.1. Renal impairmentRenal impairment

2.2. Increased intakeIncreased intake

TreatmentTreatment Phosphate binders: Alternagel, Phosphate binders: Alternagel,

Amphojel, Calcium SupplimentsAmphojel, Calcium Suppliments

Page 44: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPHOSPHOROUSPHOSPHOROUS

M.T. is a 55 year-old female with a history of M.T. is a 55 year-old female with a history of chronic renal failure who is admitted to the SICU chronic renal failure who is admitted to the SICU following a motor vehicle accident. She is following a motor vehicle accident. She is started on a TPN solution with minimal K, no Mg started on a TPN solution with minimal K, no Mg and no Phos. She also receives Mylanta II 30 ml and no Phos. She also receives Mylanta II 30 ml per NG tube every four hours. Although her per NG tube every four hours. Although her basline labs were normal on day six her labs are basline labs were normal on day six her labs are as follows:as follows:

K 4.3, Mg 2.6, Phos 1.6K 4.3, Mg 2.6, Phos 1.6

1.1. What role did the antacid play in her electrolyte What role did the antacid play in her electrolyte abnormalities?abnormalities?

2.2. What role did the TPN play?What role did the TPN play?

Page 45: Fundamentals Fluid Electrolyte Balance

ELECTROLYE DISORDERSELECTROLYE DISORDERSPHOSPHOROUSPHOSPHOROUS

M.T. is a 55 year-old female with a history of chronic renal failure M.T. is a 55 year-old female with a history of chronic renal failure who is admitted to the SICU following a motor vehicle accident. who is admitted to the SICU following a motor vehicle accident. She is started on a TPN solution with minimal K, no Mg and no She is started on a TPN solution with minimal K, no Mg and no Phos. She also receives Mylanta II 30 ml per NG tube every four Phos. She also receives Mylanta II 30 ml per NG tube every four hours. Although her basline labs were normal on day six her labs hours. Although her basline labs were normal on day six her labs are as follows:are as follows:

K 4.3, Mg 2.6, Phos 1.6K 4.3, Mg 2.6, Phos 1.6

M.T’s K is normal, but she has hypermagnesemia and M.T’s K is normal, but she has hypermagnesemia and hypophosphatemia. The antacid contributed to both of these hypophosphatemia. The antacid contributed to both of these abnormalities. It provided a significant source of Mg this patient abnormalities. It provided a significant source of Mg this patient with impaired excretion. Also the aluminum in the antacid acted a with impaired excretion. Also the aluminum in the antacid acted a phosphate binder contributing to the hypophosphatemia.phosphate binder contributing to the hypophosphatemia.

The TPN could have contributed to the hypophosphatemia by The TPN could have contributed to the hypophosphatemia by inducing an intracellular shift of phosphate (refeeding.) The inducing an intracellular shift of phosphate (refeeding.) The potassium probably remained normal because some was being potassium probably remained normal because some was being provided. Mg was being provided enterally. provided. Mg was being provided enterally.