Evaluation of bone mineral density and metabolic abnormalities associated with low-energy hip fractures

Background: Low-energy hip fractures are markers for osteoporosis. Despite a recent call for better evaluation of this issue, there is a lack of data regarding the metabolic abnormalities found in these patients and how it relates to their bone density. Additionally, no clear guidelines have been published for the evaluation of osteoporosis in these patients. We characterize the metabolic abnormalities seen in this patient population and suggest an effective screening protocol. Methods: Thirty-one patients with low-energy hip fractures not receiving osteoporosis treatment were evaluated with bone density scans and a serum metabolic evaluation consisting of a 25-hydroxyvitamin D level, parathyroid hormone level, and calcium level. The relationship of metabolic abnormalities to bone density values was evaluated. Results: Most of the patients presenting with low-energy hip fractures had metabolic abnormalities associated with low bone density. The femoral neck T-scores averaged-2.3. Fifty-three percent (16/30) of patients had low levels of vitamin D and 83% (25/30) of patients had evidence of secondary hyperparathyroidism (PTH >25 nleq/ml). We also found relatively poor correlations of bone density T-scores to parathyroid hormone and vitamin D levels (r=-0.38 and-0.05). Conclusion: Most patients presenting with low energy hip fractures have severe metabolic abnormalities associated with low bone density. Due to the poor correlation between bone density T-scores and the serum levels of parathyroid hormone and vitamin D, appropriate osteoporosis evaluation of this patient population requires both bone density evaluation and serum metabolic evaluation of 25-hydroxyvitamin D, PTH, and calcium levels.