Hypokalemia
Evaluation
General—serum potassium (K) <A onclick="get_content(event,'AB1-M12'); return false;" onmouseover="window.status=this.title; return true;" onmouseout="window.status=''; return true;" title="<3.5 mmol/L
Clinical
Weakness, paralysis, and cardiac abnormalities may occur when severe (K <A onclick="get_content(event,'AB1-M12'); return false;" onmouseover="window.status=this.title; return true;" onmouseout="window.status=''; return true;" title="<2.5 mmol/L).
Losses of large amounts of potassium can precipitate rhabdomyolysis and myoglobinuria.
Electrocardiogram (EKG) abnormalities include sagging ST segment, flat T wave, and U wave.
In those on digitalis, hypokalemia can result in a cardiac arrhythmia.
Psychiatric correlate—lithium can also produce flat T waves or inverted T waves.
Hypokalemia is a risk factor for the development of QT prolongation and torsades de pointes.
Psychiatric correlate—prescribe tricyclic antidepressants and antipsychotics with caution if the patient is hypokalemic or has other risk factors for developing QT prolongation.
Hypokalemic nephropathy and paralytic ileus can be found in long-standing potassium depletion.
Etiology
Excess renal loss (common cause of hypokalemia)
Diuretic therapy (thiazide or loop diuretics)
Mineralocorticoid excess (hyperaldosteronism, European licorice)
Carbonic anhydrase inhibitors (e.g., acetazolamide)
Osmotic diuresis—increased tubular flow rates, which increase potassium secretion
For example, in diabetic ketoacidosis (DKA) (glucose acts as an osmotic agent) there is total body potassium depletion.Related posts:
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