The primary aim was to test the hypothesis that high dietary sodium increases the calcium intakes required for optimal calcium retention in both black and white adolescent girls. Calcium retention was measured at two levels of dietary sodium in a randomized crossover design on one of two levels of dietary calcium intake in black and white adolescent girls during three week metabolic periods. The investigators hypothesized that the mechanisms which regulate sodium reabsorption in the renal tubules also regulate calcium retention. Increased incidence of hypertension in blacks compared to whites has been attributed to increased sodium retention. Sodium intake induced changes in calcium and sodium retention in both races were related to changes in sodium handling (plasma renin activity, serum aldosterone, and salt sensitivity) and calcium regulating hormones, biomarkers of bone turnover and bone mass.