ROBERT P. HEANEY, M.D.; ROBERT R. RECKER, M.D.
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.
HEANEY RP, RECKER RR. Estimation of True Calcium Absorption. Ann Intern Med. 1985;103:516–521. doi: 10.7326/0003-4819-103-4-516
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Published: Ann Intern Med. 1985;103(4):516-521.
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