title: Estimation of true calcium absorption.
abstract: Measurements of true calcium absorption fraction in women were evaluated to see how closely calculations based on a single measurement of serum specific activity after administration of an oral calcium tracer might approximate the absorption value derived from the full, double-isotope absorption procedure. True absorption, body size, and miscible pool turnover could together explain better than 93% of the variance in serum calcium specific activity values 5 hours after a tracer-labeled test meal. Because measurement of pool turnover is not available routinely, it was dropped from the model, and a predictor equation was developed that allowed estimation of true absorption from the 5-hour serum specific activity value, height, and weight. These variables explained 90.8% of the variance in the 5-hour values and gave estimates of true absorption with a 95% confidence interval of +/- 0.055. This small range of uncertainty makes the procedure useful in estimating absorption efficiency for calcium therapy in routine clinical practice.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001830:Body Surface Area; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D002132:Calcium Radioisotopes / Q000008:administration & dosage; D004041:Dietary Fats; D005243:Feces / Q000032:analysis; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007408:Intestinal Absorption; D008954:Models, Biological; D012044:Regression Analysis
chemical_list: D002132:Calcium Radioisotopes; D004041:Dietary Fats; D002118:Calcium