Does routine blood bone biochemistry predict vitamin D insufficiency in elderly patients with low-velocity fractures?

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.

During a 10-week winter period from December 2000 to February 2001, all elderly patients presenting to a general hospital in Brighton--British seaside town--with a fracture of the proximal femur and without known bone mineralisation problems were invited to participate in the study.

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 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.

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.