A 60-year-old man on ICU has severe sepsis and is commenced on IV co-trimoxazole for suspected Pneumocystis pneumonia. His potassium rises from 4.5 to...

Question

A 60-year-old man on ICU has severe sepsis and is commenced on IV co-trimoxazole for suspected Pneumocystis pneumonia. His potassium rises from 4.5 to 6.4 mmol/L over 48 hours despite no potassium-containing fluids. His renal function is mildly impaired (creatinine 150 µmol/L). What is the most likely mechanism of the hyperkalaemia?

Accepted Answer

Trimethoprim blocks renal tubular potassium secretion (similar to amiloride)

Answer

Drug-induced rhabdomyolysis

Answer

Co-trimoxazole-induced adrenal insufficiency

Answer

Haemolysis from the sulphamethoxazole component

Answer

Type 4 renal tubular acidosis from sepsis

uk-fficm MCQ (SBA): Drug-Induced Hyperkalaemia