Effect of vitamin D supplementation on total and free 25 hydroxyvitamin D and parathyroid hormone. An analysis of two randomized controlled trials

Background It is questionable as to whether total serum 25 hydroxyvitamin D (T25D) levels are lower in African Americans. We measured serum T25D, free 25hydroxyvitamin D (F25D) and serum parathyroid hormone (PTH) in African American and Caucasian women and studied the effect of vitamin D dosing to determine if differences by race or age occur. Methods Healthy young and older Caucasian and African American women who were vitamin D insufficient...