Hypokalemia

About Hypokalemia

Hypokalemia, serum potassium below 3.5 mEq L, is one of the most common electrolyte abnormalities. Causes include inadequate intake, gastrointestinal losses vomiting, diarrhea, nasogastric suction, renal losses diuretics particularly loop and thiazide, hyperaldosteronism, Cushing syndrome, Bartter syndrome, Gitelman syndrome, magnesium deficiency which impairs potassium retention, alkalosis shifts potassium into cells, and certain medications amphotericin B, cisplatin, beta agonists. Symptoms are usually mild until potassium drops below 2.5 mEq L. Muscle weakness, particularly proximal, cramping, fatigue, constipation from decreased gut motility, polyuria from nephrogenic diabetes insipidus, and cardiac arrhythmias. The ECG may show flattened T waves, ST depression, prominent U waves, and in severe cases ventricular tachycardia, torsades de pointes, or cardiac arrest. Severe hypokalemia below 2.0 mEq L can cause rhabdomyolysis muscle breakdown and ascending paralysis. Diagnosis involves assessing the cause through history, urine potassium distinguishing renal from GI losses, serum magnesium, acid base status, and in selected cases aldosterone and renin levels. Treatment depends on severity. Mild hypokalemia is often treated with oral potassium supplements prescribed by a clinician. Severe hypokalemia is a medical emergency treated in hospital with intravenous potassium given at controlled rates with cardiac monitoring, because overly rapid infusion can cause dangerous arrhythmias. Concurrent magnesium repletion is essential, as hypomagnesemia causes refractory hypokalemia. People taking diuretics are sometimes prescribed potassium supplements or potassium sparing diuretics spironolactone, amiloride.