Urinary potassium loss in children with acute liver failure and acute viral hepatitis

The aim of the present study was to determine urinary potassium (K⁺) loss (as measured by fractional excretion of K⁺ [FEK] and transtubular K⁺ gradient [TTKG]) in children with acute liver failure (ALF) and acute viral hepatitis (AVH) at the time of presentation to the hospital and day 45 of follow-up.

Twenty-five patients with ALF and 84 patients with AVH were worked up for clinical features, liver function tests, and hepatitis viral infections and monitored for outcome. All of the patients with ALF were hospitalized. FEK and TTKG were estimated on the day patients were first seen in the hospital or hospitalized and later on day 45 of follow-up.

Sixty percent (15/25) of patients with ALF were hypokalemic (serum K⁺ <3.5 mEq/L) as compared with only 12% (10/84) in the AVH group (P = 0.000) at the time of presentation in the hospital. Inappropriate kaliuresis was present in 80% to 100% of hypokalemic children compared with 0% to 30% of normokalemic individuals at the time of first contact in either the ALF or AVH group. Inappropriate urinary K⁺ loss and serum K⁺ levels in the hypokalemic individuals improved as the hepatic functions recovered by day 45 of follow-up (P = 0.014-0.000). No significant change in kaliuresis was observed among normokalemic subjects between first contact and later on day 45 of follow-up (P = 0.991-0.228). Despite different physiologic mechanisms, appropriateness of kaliuresis measured by FEK and TTKG showed results in the same direction.

Hypokalemia and inappropriate kaliuresis observed during the acute phase of ALF and AVH reversed with clinical and biochemical recovery. In the absence of major gastrointestinal losses and renal abnormalities, there is need to investigate the contributory role of factors like hyperaldosteronism and food intake, which may have therapeutic implications.