Hip fracture in elderly men: the importance of subclinical vitamin D deficiency and hypogonadism.

Abstract

To determine the major risk factors for hip fracture in elderly men. Prospective recruitment, followed by analysis of clinical and biochemical variables. Men aged 60 years and older who presented to St George Hospital (a 650-bed tertiary-care centre) in 1995, comprising all 41 men with hip fractures, as well as 41 hospital inpatient and 41 outpatient control subjects without hip fractures. Osteoporotic risk factors (including age, body weight, comorbid illnesses, alcohol intake, cigarettes smoked, and corticosteroid use) and serum concentrations of creatinine, urea, calcium, albumin, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D and free testosterone. There were no significant differences between the hip fracture and two control groups on any of the osteoporotic risk factors. Men with hip fracture had significantly lower mean serum 25-hydroxyvitamin D concentration (45.6 nmol/L; 95% confidence interval [CI], 36.9-52.3 nmol/L) than both inpatient (61.1 nmol/L; 95% CI, 50.0-72.2 nmol/L) and outpatient (65.9 nmol/L; 95% CI, 59.0-72.8 nmol/L) controls (P=0.007). Subclinical vitamin D deficiency (defined as <50 nmol/L serum 25-hydroxyvitamin D) was 63% in the fracture group, compared with 25% in the control groups combined (odds ratio, 3.9; 95% CI, 1.74-8.78; P=0.0007). Inpatients with and without hip fractures had significantly lower mean serum albumin, calcium and free testosterone concentrations than outpatients (P< 0.05). In a multiple regression analysis, subclinical vitamin D deficiency was the strongest predictor of hip fracture (beta [regression coefficient], 0.34+/-0.19; P=0.013). Subclinical vitamin D deficiency in Australian men may contribute significantly to the development of hip fracture through the effects of secondary hyperparathyroidism, resulting in increased bone loss.