A stable tracer technique for calcium metabolism studies.

A tracer technique using the stable isotope calcium-48 was developed to facilitate studies of human calcium metabolism. Small samples of 1 ml serum were used. Calcium levels were determined with good precision using neutron-activation analysis after pre-concentration of the serum calcium by oxalate precipitation. The method has sufficient sensitivity to detect induced dilutions of the tracer by administering other less costly isotopes of calcium. The ability to utilize small volumes of sample is of direct benefit to paediatric metabolism research. The favourable results obtained for two calcium loading tests demonstrate the applicability of the technique to intestinal absorption studies.