Bone mineral content in patients with calcium urolithiasis

¹²⁵I-photon absorptiometry was used to determine bone density (bone mineral content/bone width) in the distal third of the radius in 117 patients with absorptive hypercalciuria, 44 with renal hypercalciuria, 53 with primary hyperparathyroidism, and 69 patients with osteoporosis. Observed bone density in each patient was compared to the mean bone density for age- and sex-matched control subjects; the magnitude of the fractional change from control mean bone density was determined for each of the groups listed. In absorptive hypercalciuria, with normal or suppressed parathyroid function, the mean fractional change in bone density of -0.0010 was virtually identical to and not significantly different from the control mean (or zero). In renal hypercalciuria with secondary hyperparathyroidism, the mean fractional change in bone density of -0.0746 was significantly lower than the control mean (p < 0.001 by one-sample t-test; 95% confidence interval on mean fractional change ranges from -0.0970 to -0.0530). Similarly, the fractional change in bone density was significantly reduced (p < 0.001) in primary hyperparathyroidism and in osteoporosis (mean changes of -0.1275 and -0.1516, respectively). Individual value for bone density was below the lower limit of the 95% prediction interval for observations from control subjects in only one of 117 patients with absorptive hypercalciuria; it was low in 5 of 44 patients with renal hypercalciuria. These findings provide an additional support for the validity of separation of absorptive hypercalciuria from renal hypercalciuria.