A PRELIMINARY-REPORT OF VITAMIN-D AND CALCIUM-METABOLISM IN OLDER AFRICAN-AMERICANS

Objective: To determine normal serum bone-related biochemical variable s in older African-Americans. Design: A convenience sample of older Af rican-Americans who had a health screening and blood testing for calci otropic hormones was compared with white Americans who were recruited at the end of the Systolic Hypertension in the Elderly Program (SHEP) study and were not on a thiazide diuretic. Setting: Community-dwelling African-Americans who participated in SHEP or who attended one of two mass health screenings. Participants: Thirty-two African-Americans ag ed 68-93 years and 43 white Americans aged 70-89 years. Measurements: Twenty-five hydroxyvitamin D (25OHD), parathyroid hormone, osteocalcin , and calcitonin. Results: Serum 25OHD levels in 38% of the African-Am erican men and 38% of African-American women were less than 8 ng/mL co mpared with 22% of Caucasian men and 40% of Caucasian women. Serum par athyroid hormone (PTH) was above the normal range in 25% of men and 33 % of women of African-American descent and 14% of Caucasian men and 30 % of Caucasian women. Serum 25OHD was lower (P < 0.05) in individuals with a previous history of fracture. Serum albumin (P < 0.05), calcito nin (P < 0.05), and osteocalcin (P < 0.05), but not 25OHD, were lower in African-Americans (men and women) when compared with Caucasians (P < 0.05). Serum calcium corrected for albumin was higher in the African -Americans than in the Caucasians (P < 0.05). As previously reported i n Caucasians, PTH was inversely related to log 25OHD in African-Americ ans. Serum osteocalcin was positively correlated to PTH in African-Ame ricans, as previously reported in Caucasians. Log 25OHD correlated inv ersely with osteocalcin in African-Americans, but this was not seen in Caucasians. Conclusions: In this limited sample, hypovitaminosis D (a s assessed by 25OHD level) with secondary hyperparathyroidism occurred frequently in elderly African-Americans. Osteocalcin, a measure of os teoblast activity, correlated with 25OHD and parathyroid hormone. Oste ocalcin serum levels were lower in African-Americans than Caucasians, but serum calcium corrected for albumin was higher in the former compa red to the latter.