Serum Vitamin D Status and Its Relationship with Parathyroid Hormone and Bone Turnover Markers in Postmenopausal Women in Zaria, Kaduna State

Vitamin D insufficiency in postmenopausal women elevates the risk of secondary hyperparathyroidism and accelerated bone turnover, yet population-specific data from Nigerian postmenopausal women are scarce. This study assessed serum vitamin D status and its relationship with parathyroid hormone and bone turnover markers in postmenopausal women in Zaria, Kaduna State, North West Nigeria. A cross-sectional analytical design enrolled 90 postmenopausal women aged 45 to 70 years from community and hospital settings. Serum 25-hydroxyvitamin D, parathyroid hormone, osteocalcin, and C-terminal telopeptide of type I collagen were measured from fasting blood samples using enzyme-linked immunosorbent assay. Dietary calcium intake and sun exposure habits were documented. Spearman correlation and multiple regression were applied. Results showed that 66.7 percent of participants had serum 25-hydroxyvitamin D below 50 nanomoles per litre, indicating insufficiency. Despite adequate ambient solar radiation, limited skin exposure due to cultural dress practices was a significant predictor of deficiency. Parathyroid hormone was significantly elevated in vitamin D-insufficient women, and negative correlation with 25-hydroxyvitamin D was confirmed. Bone resorption marker C-terminal telopeptide was elevated in those with the lowest vitamin D levels. This study addresses a critical gap in postmenopausal bone physiology evidence from northern Nigeria. Vitamin D supplementation strategies and cultural considerations in dietary guidance are recommended. Keywords: vitamin D, postmenopausal, parathyroid hormone, bone turnover, Zaria.