[Methods for measuring the intestinal absorption of calcium in humans (author's transl)]

For the determination of intestinal absorption of calcium, the fasting (12 hours) patient receives radioactive labeled calcium (45Ca, more frequently 47Ca) by mouth. After 10, 20, 30, 60, 90, 120, 180 and 240 min, samples of venous blood are taken. The stool is also collected for three days. The determination of radiocalcium in the plasma and in the stool samples is done with a Geiger counter. This oral test provides informative results on numerous aspects of the pathophysiology of intestinal assimilation of calcium. In humans, the duodenum seems to be of the greatest importance for calcium absorption.