Is there a role for a random measurement of 24-hour urine calcium excretion in the determination of calcium supplementation in osteoporotic postmenopausal women using alendronate?

The article addresses the clinical query whether a casual determination of 24-hour urinary calcium excretion by the end of first-year treatment with alendronate in osteoporotic postmenopausal women correlates with the change in bone mineral density achieved during that year. The study included 2 arms: a prospective arm (n = 31) with women on long-term hormone replacement therapy were followed for 1 year after addition of alendronate (10 mg/daily); a retrospective arm (n = 33) with women using alendronate for 1 year. Bone mineral density and urine deoxypyridinoline were measured at baseline and 1 year, 24-hour urine calcium was obtained at 1 year. All patients used supplemental calcium, but the exact intake values were not determined. The results demonstrated no correlation between the annual increase in both spine and femur bone density and urinary calcium. Asssuming that urinary calcium correlates with calcium intake and absorption, a casual measurement of urinary calcium excretion seems irrelevant for the titration of optimal calcium supplementation in this clinical setup.