Nonoliguric hyperkalemia in neonates: a case-controlled study

The objective of this study was to determine the incidence, risk factors, and morbidities associated with nonoliguric hyperkalemia (NOHK) in neonates. Infants were eligible for the study if they were born at Al Qassimi Hospital and fulfilled the diagnostic criteria of NOHK (serum potassium [SK] > or = 7 mmol/L during the first 72 hours of life with urinary output > or = 1 mL/kg/h). The next admitted infant with gestational age +/- 1 week and normal SK acted as control. Exclusion criteria were severe congenital malformation, renal failure, failure of adequate urinary collection, and early blood transfusion within the first 72 hours of life. Fluid intake and urinary output were monitored. Infants who developed hyperkalemia (SK > or = 6.5 mmol/L in two nonhemolysed venous or arterial blood samples) had serum potassium measured every 4 hours until it reached below 6 mmol/L. Hyperkalemia was identified between 6 and 36 hours of age in 45 infants (peak SK 7 to 9.3 mmol/L). During the time of the study, the prevalence of NOHK was 24% among extremely-low-birth-weight infants (with birth weight < 1000 g) who comprised 83% of those identified. Of infants with NOHK, 13% developed tachycardiac arrhythmia and 17% died. NOHK was significantly associated with fetal distress, early metabolic acidosis, early hyperglycemia, and absence of antenatal steroid administration. Hyperkalemic infants had significantly lower serum calcium and higher serum phosphorous, urea, and creatinine. Early polyuric episodes and high urinary output were also more common in hyperkalemic infants. NOHK affects mainly preterm infants. Electrolyte disturbance and increased serum urea and creatinine were associated with hyperkalemia. Infants with NOHK also had high incidence of cardiac arrhythmias and mortality.