Calcium and vitamin D supplementation failed to improve bone mineral density in Indo-Asians suffering from hypovitaminosis D and secondary hyperparathyroidism

Abstract

Background: The association of low bone mineral density (BMD) in Asians with hypovitaminosis D (HD) and when complicated with secondary hyperparathyroidism (HD-SHPT) has been shown previously.

Objective: Our aim was to study the effectiveness of calcium and vitamin D therapy in Indo-Asians with HD and HD-SHPT.

Methods: One hundred forty-three patients attending our rheumatology clinic, including 97 (68%) with HD aged 48.9+/-11.6 years (86% female) and 46 (32%) with HD-SHPT aged 55.9+/-12.6 years (85% female), were recruited. Baseline investigations included routine biochemistry and 25-hydroxy vitamin D [25(OH)D], and parathyroid hormone (PTH) assays. Bone mineral densities (BMDs) of femoral neck, lumbar spine (LS), and distal radius (DR) were measured by dual energy X-ray absorptiometry. Patients were commenced on 1.0-1.25 g of calcium plus 400 IU of vitamin D. Blood tests were repeated at 6 and 12 months. Thirty-six patients with t scores of <-1 had their BMDs remeasured at 2 years. Unpaired t- and Mann-Whitney U tests were used in statistics. Results were considered significant at P< or =0.05.

Results: Femur t and z scores failed to improve in either group. The reduction in LS t scores but not z scores was significant in both groups. Significant reductions in DR t and z scores occurred in the HD group only. Calcium and 25(OH)D increased significantly in both groups. Alkaline phosphatase and PTH were suppressed significantly only in HD-SHPT.

Conclusion: The failure of BMD to improve could be due to lack of compliance with medication between years 1 and 2, when most patients were under the supervision of primary care. To overcome this, we recommend continuance of blood monitoring at least once a year.