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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #234444
Title: Evaluation of an inexpensive calcium absorption index in healthy older men and women

Author
item CEGLIA, LISA - JM USDA HNRCA @ TUFTS
item ABRAMS, STEVEN - BAYLOR COLLEGE OF MED
item HARRIS, SUSAN - JM USDA HNRCA @ TUFTS
item RASMUSSEN, HELEN - JM USDA HNRCA @ TUFTS
item Dallal, Gerald
item Dawson-Hughes, Bess

Submitted to: Clinical Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2009
Publication Date: 3/6/2009
Citation: Ceglia, L., Abrams, S.A., Harris, S.S., Rasmussen, H.M., Dallal, G., Dawson-Hughes, B. 2009. Evaluation of an inexpensive calcium absorption index in healthy older men and women. Clinical Endocrinology. DOI: 10.1111/j.1365-2265.2009.03576.x.

Interpretive Summary: Calcium absorption is an important determinant of calcium retention and bone metabolism and a valuable measurement in clinical investigation. The gold-standard method for measuring absorption is the double stable isotope method; however, this method is costly and cumbersome to implement. In this study, we determined whether urinary calcium excretion after an oral dose of calcium may be a useful index of calcium absorption in older adults. We evaluated this in eleven healthy older adults who were consuming the recommended amount of calcium in their diets. After 10-days on a diet containing 1200 mg/day of calcium, calcium absorption was measured using the dual stable isotope method. On the same day, we measured urine calcium excretion over the 4-hr period following their consumption of a light breakfast containing 400 mg of calcium. Calcium excretion over four hours following the calcium dose was significantly correlated with absorption by the gold standard method (r=0.735, P=0.010). In conclusion, 4-hour urinary calcium excretion after a 400 mg calcium load is a practical index of calcium absorption in healthy older adults consuming 1200 mg/day of calcium. This simple urine test is inexpensive and easy to implement, and could be useful in large clinical studies for which the cost of more sophisticated measurements would be prohibitive.

Technical Abstract: Calcium absorption is an important determinant of calcium retention and bone metabolism. However, most methods of measuring calcium absorption, including the well-established dual stable isotope method, are costly and cumbersome to implement. We evaluated eleven healthy subjects age 54-74 to determine whether an oral calcium tolerance test (OCTT) in which involves measuring calcium excretion in a fasting 2-hr urine collection and two 2-hr collections following an oral calcium dose, may be a useful index of calcium absorption in older adults consuming a fixed calcium intake of 1200 mg/day. After a 10-day metabolic diet containing 1200 mg/day of calcium, subjects had calcium absorption measured using the dual stable isotope method and the OCTT. The main outcome measure was Fractional calcium absorption (FCA), calcium excretion in a fasting 2-hr urine collection and two 2-hr collections in response to a 400-mg calcium dose (total intake 1200 mg/day). Calcium excretion from several combinations of the urine collections was examined in relation to FCA. The most predictive of FCA was calcium excretion four hours following the calcium dose. This measure was significantly correlated with FCA (r=0.735, P=0.010), fitting 54% of the variability in FCA. Urinary calcium excretion during the four hours after a 400-mg calcium dose is a useful index of calcium absorption among older adults consuming recommended calcium intakes. This test is inexpensive, easy to implement, and potentially useful in large clinical studies.