Hyperkalemia in very low birth weight infants

Purpose: To assess the frequency and pathogenesis of hyperkalemia in the very low birth weight infant. Infants who weighed less than 1000 gm at birth were prospectively entered into the study within 12 hours of birth. Potential risk factors for hyperkalemia were assessed. Body weight, fluid and electrolyte balance, serum levels of sodium and potassium, creatinine clearance, fractional sodium excretion, and urine sodium/potassium ratio were measured every 8 hours for 72 hours. Measurements of plasma renin, serum aldosterone, and plasma atrial natriuretic factor were made at study entry and repeated when hyperkalemia (serum potassium >6.5 mmol/L) occurred or at 72 hours. Infants in whom hyperkalemia developed were compared with those in whom it did not. Thirty-one infants completed the study; hyperkalemia developed in 16 (51.6%). The only difference in the occurrence of perinatal complications was the more frequent occurrence of pH