Assessment of Stable Isotopes of Calcium for the Measurement of Intestinal Calcium Absorption
Intestinal absorption of calcium in man can be determined by tracer methods. Radioactive as well as stable isotopes of calcium have been used as tracers, the radioisotopes being used more commonly (Behne et al. 1978, Werner et al. 1981). However, stable isotopes are of special interest for studies in children and pregnant women, in whom the use of radiactive isotopes is restricted. The establishment of reference values for these groups depends on the practicability to employ non-radioactive isotopes as tracers. Up to now, only a few authors have reported data on calcium metabolism in children. All previous studies applying stable calcium isotopes as tracers are based on the measurement of 46Ca and 47Ca by neutron activation analysis. A major problem of this method is that large sample volumes are necessary to obtain sufficient precision (approx. 4 ml of blood for ± 1%). This excludes kinetic studies in infants or newborns, where multiple sampling is required. Mostly, only excretion measurements (urine and faeces) have been performed by neutron activation analysis. Furthermore, this technique is restricted to the isotopes 46Ca and 48Ca.
KeywordsOsteoporosis Radioactive Isotope Deconvolution Gluconate Reten
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