• M Di Monaco, C Castiglioni, F Vallero, R Di Monaco, and R Tappero.
• Osteoporosis Research Center, Division of Physical Medicine and Rehabilitation, Presidio Sanitario San Camillo, Torino, Italy. marco.di.monaco@alice.it
• J Nutr Health Aging. 2013 Feb 1;17(2):180-4.

ObjectivesTo investigate the association between sex and parathyroid hormone response to severe vitamin D deficiency after hip fracture.DesignCross-sectional study.SettingRehabilitation hospital in Italy.Participants571 consecutive inpatients with hip fracture and severe vitamin D deficiency (serum 25-hydroxyvitamin D < 12ng/ml), without hypercalcemia or estimated glomerular filtration rate (GFR) < 15ml/min.MeasurementsIn each patient we assessed PTH (by two-site chemiluminescent enzyme-labelled immunometric assay), 25-hydroxyvitamin D (by immunoenzymatic assay), albumin-adjusted total calcium, phosphate, magnesium, and creatinine 21.3 ± 6.1 (mean ± SD) days after fracture occurrence. Functional level was assessed using the Barthel index. PTH response to vitamin D deficiency was classified as either secondary hyperparathyroidism (serum PTH >75pg/ml) or functional hypoparathyroidism, i.e., inappropriate normal levels of PTH (≤75pg/ml).ResultsAmong the 571 patients, 336 (59%) had functional hypoparathyroidism, whereas 235 (41%) had secondary hyperparathyroidism. PTH status was significantly different between sexes (p=0.003): we found functional hypoparathyroidism in 61% of women and 43% of men (secondary hyperparathyroidism in 39% of women and 57% of men). The significance of the between-sex difference was maintained after adjustment for age, estimated GFR, phosphate, albumin-adjusted total calcium, albumin, Barthel index scores, 25-hydroxyvitamin D, and hip fracture type (either cervical or trochanteric). The adjusted odds ratio was 1.85 (95%CI from 1.09 to 3.13; p=0.023).ConclusionsData shows that PTH response to vitamin D deficiency was sex-associated following a fracture of the hip. The higher prevalence of secondary hyperparathyroidism may play a role in the known prognostic disadvantage found in hip-fracture men.

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