Does Routine Blood Bone Biochemistry Predict Vitamin D Insufficiency in Elderly Patients with Low-Velocity Fractures?

Abstract

Purpose. Vitamin D deficiency impairs bone mineralisation and can predispose individuals to fractures. This study aimed at testing whether measurement of plasma calcium, alkaline phosphatase, and phosphate levels could detect vitamin D insufficiency. Methods. During a 10-week winter period from December 2000 to February 2001, all elderly patients presenting to a general hospital in Brighton—a British seaside town—with a fracture of the proximal femur and without known bone mineralisation problems were invited to participate in the study. Results. 23 (63.9%) of the 36 eligible patients had insufficient levels of vitamin D, with a plasma concentration of less than 30 nmol/L. The mean parathyroid hormone level was 56 pg/mL (range, 12–193 pg/mL). 11 of the 36 patients had an elevated level of parathyroid hormone and were insufficient in vitamin D. The mean plasma concentration of calcium was 2.30 mmol/L (range, 2.05–2.98 mmol/L). The mean phosphate level was 0.98 mmol/L (range, 0.40–1.79 mmol/L), and the mean alkaline phosphatase level was 91 IU/L (range, 46–127 IU/L). There was poor correlation between vitamin D insufficiency and plasma calcium, alkaline phosphatase, or phosphate levels. Conclusion. Plasma calcium, alkaline phosphatase, and phosphate testing cannot detect vitamin D insufficiency. We recommend that vitamin D and calcium supplementation be considered for patients with low-energy hip fractures.