Hypomagnesaemic hypocalcaemia with hypokalaemia caused by treatment with high dose gentamicin.

A 12-year-old boy developed renal wasting of magnesium, calcium, and potassium, with secondary hypomagnesaemia, hypocalcaemia, and hypokalaaemia (without hyperaldosteronism) after treatment with 14 400 mg gentamicin over 4 months. Gentamicin should not be given for prolonged courses if less toxic antibiotics are suitable. If it used, plasma magnesium, calcium, and potassium levels should be monitored during and after treatment.