Clinical studies of intestinal 47Ca absorption test by external arm counter

An arm counter used to measure fractional accumulation of 47Ca on the forearm following an intravenous and a later oral dose of the radioisotope, and the intestinal 47Ca absorption rate was calculated. Clinical studies were carried out in normal subjects and patients with some disorders of calcium metabolism, using this external counting techinique. The following results were obtained; (1) In 12 healthy control men (mean age 31.8 y), calcium absorption rate ranged from 42.5% to 59.6% (mean+-SD; 54.1+-4.7%). In 6 healthy women (mean age 31.4 y), the rate ranged from 46.8% to 57.3% (mean+-SD; 51.3+- 4.3%). The intestinal calcium absorption was not related to the sex in younger adult. (2) The fractional absorption of calcium were significantly increased in patients with primary hyperparathyroidism, whereas reduced in hypoparathyroidism. (3) In 5 female subjects affected by osteoporosis, a defective intestinal absorption of calcium was observed. (4) The calcium absorption tests were carried out on normo- and hypercalciuric patients with calcium urolithiasis. Higher absorption of calcium was recognized in some hypercalciuric patients. (5) In hypercalciuric calcium stone formers with rice-bran treatment, 47Ca absorption from gut were decreased significantly. (6) This method is very convenient to determine the intestinal absorption of 47Ca. When a protective covering of lead is prepared for scintiscanner, the 47Ca absorption test can be done for the patients with calcium metabolic disorder on a routine examination. (author)