Zonisamide-induced distal renal tubular acidosis and critical hypokalaemia

Abstract

A woman in her 20s presented with rapidly progressive muscle weakness and a 1-month preceding history of fatigability, nausea and vomiting. She was found to have critical hypokalaemia (K⁺ 1.8 mmol/L), a prolonged corrected QT interval (581 ms) and a normal anion gap metabolic acidosis (pH 7.15) due to zonisamide-induced distal (type 1) renal tubular acidosis. She was admitted to the intensive care unit for potassium replacement and alkali therapy. Clinical and biochemical improvement ensued, and she was discharged after a 27-day inpatient stay.

Keywords: Adult intensive care; Epilepsy and seizures; Fluid electrolyte and acid-base disturbances; Neurology (drugs and medicines).

Figure 1

Serum potassium (K⁺), pH, bicarbonate (HCO₃⁻) and chloride (Cl⁻) response to therapy during critical care admission (normal ranges in coloured rectangles).