Hyperkalemia in the neonatal intensive care unit: actual or pseudohyperkalemia?

Hyperkalemia is a critical electrolyte imbalance in neonatal intensive care unit (NICU), linked to increased mortality. This study aimed to determine the prevalence, etiological factors, and clinical outcomes of hyperkalemia in neonates admitted to the NICU over a 10-year period, with a specific focus on differentiating actual hyperkalemia from pseudohyperkalemia according to gestational age - based thresholds.

Data from NICU admissions over 10 years were analyzed. Hyperkalemia was defined as potassium levels ≥6 mmol/L in term neonates and >6.5 mmol/L in preterm. Cases of pseudohyperkalemia, primary etiology, and mortality were assessed.

Among 5997 admissions, hyperkalemia was observed in 4.9% of cases, while true hyperkalemia was confirmed in 1.6%. Pseudohyperkalemia was the most common type. Actual hyperkalemia was more frequent in term neonates (p = 0.016). Acute kidney injury (AKI) was identified in 43.6% of cases. In term neonates, the most common causes were asphyxia, AKI, and congenital adrenal hyperplasia, whereas in preterms, they were AKI, hypoxia, and hemorrhage. A negative correlation was found between Apgar scores and potassium levels (p < 0.001). Mortality rates were 7.2% in neonates without actual hyperkalemia and 37.2% in those with it.

Hyperkalemia is a common and serious condition in NICUs, requiring prompt differentiation of pseudohyperkalemia from actual hyperkalemia. Given its high mortality risk, rapid etiology-specific treatment and potassium-lowering therapies are essential for managing actual hyperkalemia.