THE DISTRIBUTION OF CALCIUM GIVEN TO HUMAN SUBJECTS BY SUSTAINED INTRAVENOUS INFUSION

Abstract

Solutions of calcium gluconate which contained known amounts of Ca45 were given to human subjects by intravenous infusion (usually 110 mg of calcium per hour for four hours). Because the specific activity of the infused calcium was known, its subsequent distribution and excretion could be followed. It was found that the infused calcium left the plasma rapidly. The approximate amount of calcium into which the administered calcium appeared to mix was calculated. This varied between 1.5 and 3.1 Gm. in patients with osteoporosis, was 4.1 Gm. in a patient with a parathyroid adenoma and 7.3 Gm. in a subject with Paget''s.disease. Although the amount of calcium excreted in the urine on the day of the infusion was greatly increased in all patients (equal to 34-98 per cent of the amount of calcium administered) most of the excreted calcium was from sources other than the infusion. From 1.6 to 13.0 per cent of the infused calcium appeared in urine during the first twenty-four hours.