Increased serum calcium levels induced by furosemide

Thirteen male patients were treated with furosemide at a dosage of 40 mg by mouth daily for three weeks. Atomic absorption serum calcium determinations before and after treatment revealed a consistent elevation of the serum calcium level. It is suggested that at low dosages, furosemide is likely to raise the serum calcium level, while at daily dosages greater than 60 mg given orally, furosemide may depress the serum calcium level because of urinary losses.