Etiologic and therapeutic analysis in patients with hypokalemic nonperiodic paralysis.

BACKGROUND

Hypokalemic nonperiodic paralysis represents a group of heterogeneous disorders with a large potassium (K(+)) deficit. Rapid diagnosis of curable causes with appropriate treatment is challenging to avoid the sequelae of hypokalemia. We prospectively analyzed the etiologies and therapeutic characteristics of hypokalemic nonperiodic paralysis.

METHODS

Over an 8-year period, patients with hypokalemic nonperiodic paralysis were enrolled by excluding those with hypokalemic periodic paralysis due to acute shift of K(+) into cells. Blood and spot urine samples were collected for the measurements of electrolytes, pH, and biochemistries. Intravenous potassium chloride (KCl) at a rate of 10-20 mmol/h was administered until muscle strength recovered.

RESULTS

We had identified 58 patients with hypokalemic nonperiodic paralysis from 208 consecutive patients with hypokalemic paralysis, and their average K(+) concentration was 1.8 ± 0.2 mmol/L. Among patients with low urinary K(+) excretion (n = 17), chronic alcoholism, remote diuretic use, and anorexia/bulimia nervosa were the most common causes. Among patients with high urinary K(+) excretion (n = 41) and metabolic acidosis, renal tubular acidosis and chronic toluene abuse were the main causes, while primary aldosteronism, Gitelman syndrome, and diuretics were the leading diagnoses with metabolic alkalosis. The average KCl dose needed to restore muscle strength was 3.8 ± 0.8 mmol/kg. Initial lower plasma K(+), volume depletion, and high urinary K(+) excretion were associated with higher recovery KCl dosage. During therapy, patients with paradoxical hypokalemia (n = 32) who required more KCl supplementation than patients without (4.1 ± 0.7 vs 3.4 ± 0.7 mmol/kg, P < 0.001) often exhibited significantly higher plasma renin activity and received a higher volume of normal saline before its appearance.

CONCLUSIONS

Understanding the common etiologies of hypokalemic nonperiodic paralysis may aid in early diagnosis. Patients with initial lower plasma K(+), renal K(+) wasting, and hypovolemia required higher recovery K(+) dosage. Paradoxical hypokalemia is prone to develop in hypovolemic patients even during K(+) supplementation with volume repletion.