Characteristics of nonoliguric hyperkalemia in preterm infants: A case‐control study in a single center

Abstract

Preterm infants often present with hyperkalemia during the first days after birth without showing oliguria, which is known as nonoliguric hyperkalemia (NOHK). As its clinical features have not been completely understood to date, we aimed to elucidate the characteristics of NOHK, including its risk factors in preterm infants. For this case-control study, we reviewed the files of all infants born before 32 weeks of gestational age in our neonatal intensive care unit between 2011 and 2018. We distinguished the NOHK and non-NOHK groups and compared their characteristics and blood potassium levels. NOHK was defined as peak blood potassium concentration of ≥ 6.0 mmol/L during the first 72 hours of life with a urine output of ≥ 1 mL/kg/h. Of the 99 infants enrolled, 21 (21%) demonstrated NOHK. Infants in the NOHK were more likely to have been exposed to antenatal magnesium sulfate (MgSO4 ) (P = 0.019) than those in the non-NOHK group. Acute morbidities and mortality were not statistically different. On multivariable analysis, we found that administration of maternal MgSO4 for longer than 24 hours at any point before delivery was a risk factor for NOHK. Its adjusted odds ratio and 95% confidence intervals were 4.0 and 1.4－12.3, respectively (P = 0.012). In this study, maternal MgSO4 administration for longer than 24 hours proved to be a risk factor for NOHK in infants born before 32 weeks of gestational age. Infants born to mothers who have received MgSO4 should be regularly monitored for their electrolytes.