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Electrolyte Imbalance

Introduction Causes Clinical Manifestations Diagnosis Treatment
Hyponatremia Decrease in serum sodium concentration <136 meq/L caused by excess of water relative to solutes a) Euvolemic Hyponatremia-Polydipsia, Administration of hypotonic fluid, SIADH, Addison’s disease, Hypothyroidism
b) Hypovolemic hyponatremia
i) Renal– Acute or chronic renal  insufficiency, salt wasting nephropathy, use of diuretics,
ii) Extra Renal-vomiting, diarrhea, excessive sweating, prolonged exercise or sodium and water loss but only water is replaced.
c) Hypervolemic Hyponatremia-
i) Renal- Acute or chronic Renal failure nephrotic syndrome
ii) Extra renal- Cirrhosis of liver, Congestive heart failure,
Primarily neurological (Due to osmotic shift of water in to brain cells) and include- Headache, confusion, seizures and coma. 1) Serum and urinary osmolality- serum osmolality may be low but urinary osmolality may be high.2) Serum Sodium –low

3)BUN and creatinine- Normal but high in renal failure.

a) Euvolemia- Treat the primary causeb) Hypovolemia- 0.9% Saline

c) Hypervolemia- fluid restriction and diuretics

Hypernatremia Increase in serum sodium concentration > 145 meq/L caused by a deficit of total body water relative  to total body sodium a) Euvolemic Hypernatremia- i)Renal losses- Central diabetes Insipidus, Nephrogenic diabetes Insipidusii) Extra renal losses- Respiratory tract (Tachypnea). Skin (Fever)

iii) Misc- Decreased thirst

b) Hypovolemic Hypernatremia-

i) GI Losses- Diarrhea, vomiting

ii) Skin- Burns, excessive sweating

iii) Renal losses-Interstitial kidney disease, diuretics etc.

c) Hypervolemic hypernatremia- Administration of hypertonic fluid, saline or sodium bicarbonate, excess mineralocorticoids


Thirst, CNS Dysfunction, confusion, seizures or coma, decreased skin turgor in severe cases 1) Serum sodium high2) BUN , creatinine high- if kidneys are involved

3) Urinary sodium- > 20 meq/L in Hypovolemic hypernatremia and

< 20 meq/L  if there are extra renal losses.


a) Euvolemic Hypernatremia- 5% D/W or 0.45% salineb) Hypovolemic Hypernatremia-

0.45% saline or a combination of 0.9% normal saline and 5% D/W

c) Hypervolemic hypernatremia-

5% D/W with loop diuretics

d) Sodium restricted diet

Hypokalemia Serum K concentration < 3.5 meq/L, caused by deficit in total body K or shift of potassium in to the cells i) Renal Losses- Renal tubular acidosisii) Adrenal steroid excess- Cushing syndrome, Hyperaldosteronism

iii) GI Losses- Vomiting, diarrhea, laxative abuse

iv) Drug induced- Diuretics, Beta 2 adrenergic agonists, steroids, theophyllin, insulin administration

v) Metabolic alkalosis

vi) Familial periodic paralysis

Fatigue, Myalgias, weakness, hypoventilation, impaired muscle metabolism, glucose intolerance 1)Serum potassium is lowa) ECG- Findings-Sagging of ST segment. T wave depression, elevation of U wave.

AV blocks  or Arrhythmias in severe cases

3) BUN and Creatinine may be high, serum calcium high, Ph High. Blood glucose may be high

Supplementation by oral route or I/V KCl mixed in normal saline.
Hyperkalemia Serum K concentration > 5.5 meq/L from excess total body potassium stores or abnormal movement of K out of the cells a)Pseudohyperkalemia– Hemolysis, Thrombocytosis, Leukocytosisb) Redistribution- Acidosis, Insulin deficiency, beta blocker drugs, digitoxin overdosage, hyperkalemic periodic paralysis

c) Excessive endogenous load- Hemolysis, Rhabdomyolysis, Internal hemorrhage

d) Excessive exogenous load- Parenteral administration, excess in diet, K supplements.

e) Diminished excretion- Renal failure, renal tubular acidosis


Fatigue, Paresthesias, paralysis, palpitations, bradycardia, decreased tendon reflexes, decreased motor strength.Signs of renal failure or muscle paralysis may be there. 1) Serum K is low2) ECG- Increased PR interval, Tall , symmetric , peaked T waves.

In severe cases- widening of QRS interval, ventricular arrhythmias, ventricular fibrillation

3) BUN, Creatinine may be high

4) Blood glucose high in diabetes mellitus

5) PH low in acidosis

1) Supplement with calcium chloride or calcium GluconateTo restore resting membrane potential

2) Insulin with glucose supplementation to promote intracellular shift.


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