Causes of Hypokalemia
I. Decreased intake
A. Starvation
B. Clay ingestion
II. Redistribution into cells
A. Acid-base
1. Metabolic alkalosis
B. Hormonal
1. Insulin
2. Increased ß2-adrenergic sympathetic activity: post-myocardial infarction, head injury
3. ß2-Adrenergic agonists - bronchodilators, tocolytics
4. a-Adrenergic antagonists
5. Thyrotoxic periodic paralysis
6. Downstream stimulation of Na*/K+-ATPase: theophylline, caffeine
C. Anabolic state
1. Vitamin or folic acid administration (red blood cell production)
2. Granulocyte-macrophage colony-stimulating factor (white blood cell production)
3. Total parenteral nutrition
D. Other
1. Pseudohypokalemia
2. Hypothermia
3. Familial hypokalemic periodic paralysis
4. Barium toxicity: systemic inhibition of "leak" K* channels
Ill. Increased loss
A. Nonrenal
1. Gastrointestinal loss (diarrhea)
2. Integumentary loss (sweat)
B. Renal
1. Increased distal flow and distal Na• delivery: diuretics, osmotic diuresis, salt-wasting nephropathies
2. Increased secretion of potassium
a. Mineralocorticoid excess
b. Apparent mineralocorticoid excess
c. Distal delivery of nonreabsorbed anions
3. Magnesium deficiency
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