ELECTROLYTE IMBALANCE

Dr. Vignesh kumarAmbedkar hospital

http://www.globalrph.com/index.htm

Composition in body compartments

Electrolyte ECF (mEq/l) ICF (mEq/l)

Sodium 135-150 10-18

Potassium 3.5-5.0 120-145

Calcium 8.5-10.5 mg/dl

Magnesium 1.5-2.4 30-50

Chloride 95-108 2-6

Phosphate 2.5-4.5 mg/dl 25-60

Bailey&Love 26th ed., Schwartz 9th ed.

Composition of GI secretions(mEQ/l) Sodium Potassium Chloride Bicarbonate

Saliva 10 25 10 30

Stomach 60-90 10-30 100-130

Duodenum 140 5 100

Mixed gastric

aspirate

120 10 100

Ileum 140 5 100 30

Colon 60 30 40

Stool 35 3-12 20

Pancreas 140 5 75 115

Bile 140 5 100 35

POTASSIUMPrimary intracellular ionRegulates cell excitabilityRDA : 4700 mg

(0.6-0.8mEq/kg/day)Regulated be renin-angiotensin-

aldosterone axisRelation to acid base

balance(buffer)potassium decreases by 0.3

mEq/l for every 0.1 increase in pH

ETIOLOGY

HYPERKALEMIA HYPOKALEMIA

Increased intake Increased secretion Impaired excretion

Inadequate intakeExcessive excretionGI lossesMisc

Treatment of hypokalemiaCorrection = 0.4× Body weight×

deficitOral / IVHow much to correct?Peripheral/central line?Refractory cases?? Why?Co-existing hypokalemia and

acidosis, what to correct first?

Treatment of hyperkalemiaStop all oral and iv infusions of

potassiumStabilize the heartRole of bicarbonate??Short term measuresPermanent measures

SODIUMPrimary extracellular ionVital for homeostasis and action

potential in the bodyControls water movement in and out

of the vascular systemRegulated by ADHRDA : 2400mg (1-2mEq/kg/day)Serum osmolality

◦2×Na + BUN/2.8 + glucose/18◦2×Na + Bl urea/6 + glucose/18

Hyponatremia Hypotonic/hypertonicEvery 100 gm fall in glucose,

1.6mEq/l fall in na (transient h-na)

Renal/ extra renalVolume statusADH – H-na – osmalilty SIADH

Treatment of hyponatremiaCorrection = 0.6(m)/0.5(f) × deficit × BW

Na <110 or neurological symptoms◦3% NS until Na >120 or symptom free◦Rate of correction 0.25 mEq/l/hr or 8

mEq/l/day◦Seizures are present, correction can be upto

4-5 mEq/l in first hour◦Central pontine myelinosis

Hypovolemia Euvolemia Hypervolemia

Salt and water Water restriction Salt & Water restriction

IV saline Loop diuretics

Hypernatremia Volume statusRenal / extra renalDiabetes insipidusSr.osmalalityRare for a thristy person to end

up with hypernatremia

Treatment of hypernatremiaVolume status

Rate of correction◦Acute – max of1-2 m Eq/l/hr◦Chronic – max of 0.5 mEq/l/hr◦Max of 8 mEq/l/day

Diabetes insipidus

Hypovolemia Euvolemia Hypervolemia

NS/2 and D5 Water or D5 Salt restriction

Loop diuretics with water

CALCIUMRegulated by PTH and CalcitoninVitamin D plays a role in absorptionCoagulation cascade, neuromuscular

functionIonic 50%, protein bound 40%, anion

bound 10%RDA : 1-2gIonic ca = total ca + [0.8×(4.5-albumin)]Relation to acid-base balance

◦Acidosis decreases protein bound ca levels

ETIOLOGY

HYPOCALCEMIA HYPERCALCEMIAPost thyroid and neck

surgeryEndocrineRenal failureHyperphosphatemia Malignant diseaseNutritionalBlood transfusion Inflammatory

conditions

EndocrineRenal dysfunctionMalignant diseaseNutritionalGranulomatous

disease Inherited disorders

Chvostek’s sign

Trosseau’s sign (carpopedal spasm)

Treatment of hypocalcemia

10ml of 10% calcium gluconate(1 gm) f/b calcium infusion if necessary (0.5-1.5mg/kg/hr)

Gluconate preferred over chlorideHyperphosphatemia correctionRefractory cases? Why?Oral supplementation with

vitamin DTeriparatide (synthetic PTH)

HYPERCALCEMIASIGNS AND SYMPTOMS

Treatment of hypercalcemiaTreat the etiology – m/c

parathyroid adenomaStop thiazide diureticsSaline diuresis with furosemideInhibit bone resorption

(biphosphonates)HemodialysisCalcitonin as short term measureOral phosphates

MAGNESIUMNormal levels 1.5-2.4 m Eq/lProtein bound(30%), anion

bound(10%) and free(60%)Calcium channel antagonist and co

factor in ATP powered reactionsPhysiological test to detect tissue H-

MgMg is reabsorbed in Henle’s loop and

DCTRDA : 400mg

Hypomagnesemia40% of hypomagnesemics are

hypokalemic60% of hypokalemics are

hypomagnesemicHypomagnesemia

Slows ATP production

Na+-K+ ATPase

Loss of intracellular potassium

Loss of potassium in urine

Treatment of hypomagnesemia1gm MgSo4 contains 0.1 g of

elemental magnesium8-12g IV over 24 hours f/b 4-6g

IV for the next three daysDose to be adjusted in renal

insufficiencyDeep tendon reflexes, RR, Urine

output to be checked while giving Mg correction

Hypermagnesemia Uncommon in the absence of

renal failureIV overdose are better tolerated

than oral overdoseNeuromuscular blockadeCalcium channel blockade ECG changes

Treatment of hypermagnesemiaStopping Mg in patients with

intact renal function will sufficeCalcium to stabilize the heartSaline diuresis with loop diureticsDialysis for renal failure patients