VITAMIN D STATUS AND ITS RELATIONSHIP WITH BONE MINERAL DENSITY AND PARATHYROID HORMONE IN SOUTHEAST ASIAN ADULTS WITH LOW BONE DENSITY

Objective: To investigate the vitamin D sufficiency status and the relationships among serum 25-hydroxyvitamin D [25(OH) D] levels, intact parathyroid hormone (iPTH) levels, and bone mineral density (BMD) in patients attending an osteoporosis clinic in Singapore. Methods: In total, 193 adults with or without prevalent fragility fractures and with low BMD at the femoral neck, total hip, or lumbar spine underwent assessment. Multivariate regression models were used to investigate the relationships among serum 25(OH) D, iPTH, and BMD. Results: The mean values (standard deviation) for age of the patients and serum 25(OH) D level were 61 (14) years and 26.05 (7.97) ng/mL, respectively. In 72% of patients, serum 25(OH) D levels were below 30 ng/ mL. There was no association between 25(OH) D levels and BMD at the femoral neck, total hip, or lumbar spine (P = .568, .461, and.312, respectively). Serum iPTH levels were negatively associated with BMD at the total hip (P = .035) and the lumbar spine (P = .019). At levels <30 ng/ mL, 25(OH) D was negatively associated with iPTH (P = .036). Conclusion: Among this Southeast Asian population of patients with low BMD, no direct relationship between serum 25(OH) D levels and BMD was observed. A negative correlation existed, however, between iPTH and 25(OH) D at serum 25(OH) D concentrations <30 ng/ mL, and serum iPTH levels showed a significant negative association with BMD at the total hip and lumbar spine. These significant negative associations between iPTH levels and BMD at the total hip and lumbar spine underscore the critical role of this hormone in bone metabolism and health.