Secondary hyperparathyroidism, vitamin D deficiency and hip fracture: importance of sampling times after fracture

There is controversy about how often elevated parathyroid hormone (PTH) levels are found in hip fracture patients. The aim of this study was to determine whether changes in PTH levels after fracture and surgery could explain some of the variation in published data. Blood samples were obtained from 24 elderly patients with hip fracture before surgery, immediately after surgery and at 2 weeks and 3 months after fracture. PTH levels were elevated (> 5.5 pmol) in 33% initially and then fell significantly at 2 weeks in virtually all subjects (P < 0.001) and remained significantly lower after 3 months (n = 17). Although 25-hydroxyvitamin D levels were low (< 30 nmol) in 44% of the patients, the fall in PTH was not explained by alterations in vitamin D metabolites or other measured parameters. The cause of the variation in PTH levels is unknown but measurements immediately after fracture could overestimate the incidence of secondary hyperparathyroidism. Vitamin D deficiency is common in our hip fracture population and is not influenced by hospitalisation.