Objectives: Acidosis is now recognized as an important component of the severe malaria syndrome and a predictor of fatal outcome. Alterations in plasma potassium concentrations are commonly associated with acidosis. To date, there is little information about the changes in potassium in severe malaria.
Design: Prospective study examining the changes in plasma potassium in the first 24 hrs following admission in children with severe malaria. Urinary fractional excretion of potassium and the transtubular gradient of potassium were examined at admission.
Setting: High-dependency unit on the coast of Kenya.
Patients: Kenyan children admitted to hospital with clinical features of severe malaria (impaired consciousness or deep breathing) complicated by acidosis (base deficit >8).
Interventions: Children received standard therapy for severe malaria; in addition, they received boluses of either 0.9% saline or 4.5% human albumin solution to correct hypovolemia, and intravenous potassium replacement was prescribed to children who developed hypokalemia (plasma potassium <3 mmol/L).
Measurements and main results: Thirty-eight Kenyan children were recruited with severe malaria and acidosis. At admission, serum potassium was normal (3-5.5 mmol/L) in 31 (81.6%) and low (<3 mmol/L) in four (11%) children, and three (6.3%) children had hyperkalemia (>5.5 mmol/L). Plasma potassium decreased rapidly within 4-8 hrs of admission: 15 (40%) patients were hypokalemic (<3 mmol/L); of these, five (13%) had plasma potassium of <2.5 mmol/L. Fractional excretion of potassium and the transtubular gradient of potassium were above normal range, indicating renal potassium loss.
Conclusions: Hypokalemia is a common complication of severe malaria; however, it is often not apparent on admission. On correction of acidosis, plasma potassium decreases precipitously, and thus careful, serial monitoring of serum potassium is suggested in patients with severe malaria complicated by acidosis.