Usefulness of 45Ca intestinal absorption tests in the clinical situation

Radioactive isotopes of calcium were used to measure calcium absorption in patients with various diseases. In most clinical groups there was great variation in plasma concentration after oral administration with overlap with the normal group. Patients with uraemia and pancreatectomy showed significantly low values. A method for calculating absorption and removal constants of radioactive calcium is described, and methods of calculating absorption and removal constants are discussed. It was concluded that these calculations do not add information to that obtained from plasma concentrations. Plasma concentrations after oral ingestion of radioactive calcium are of value mainly in following the course of disease in individual patients