Factors causing hyperkalemia in premature infants.

In order to clarify the causative factors of hyperkalemia in premature infants, 48 newborn infants less than 2000 gm birthweight were examined during the first 48 hours of life. They were divided into two groups: group A (n = 19), which had more than 7 mEq/liter of serum potassium level, was defined as a hyperkalemic group; group B (n = 29) had less than 6.9 mEq/liter of serum potassium level throughout this study period. In group A hyperkalemia occurred on the first day of life and continued throughout the study period. Five of group A infants had arrhythmia, one of whom died from cardiac arrest on the second day of life. Laboratory findings (serum creatinine, creatine phosphokinase, electrolytes, blood gas analysis, calorie balance, and renal function) were compared between the two groups. On the first day of life, serum creatinine and creatine phosphokinase concentrations were significantly elevated and calorie intake was decreased in group A when compared with group B. On the second day of life, calorie intake, urine volume, creatinine clearance, and base excess were significantly decreased in group A. A significant decrease was observed in the serum calcium level in group A on the second day of life when compared with admission data. These data suggest that neonatal hyperkalemia may occur in the sick newborn infants with renal dysfunction when combined with metabolic acidosis and catabolic state.