Vitamin D and intact PTH status in patients with hip fracture

Abstract

The prevalence of hypovitaminosis D in patients with acute hip fracture was examined in a population on Sado Island in Japan. There were 85 cases of hip fracture among this population in 2004, giving an overall incidence of hip fracture of 121.4 per 100,000 population per year. This study included 50 of the 85 cases, and these cases were defined as the hip fracture group. Patients older than 70 years without established osteoporosis who were admitted to the hospital on the island during almost the same period for treatment of an orthopedic condition other than a hip fracture were defined as the control group. The levels of serum 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone (intact PTH), alkaline phosphatase (ALP), albumin, and the number of remaining teeth were examined in each group. In the hip fracture group, serum calcium, serum phosphorus, urine N-terminal cross-linking telopeptide of type I collagen (NTx), bone mineral density (BMD) of the nonfractured hip, the presence of a vertebral fracture on X-ray, severity of dementia, and physical activity level were also examined. Both the serum 25-OHD and serum albumin levels were significantly lower in patients with hip fracture than in controls, and the intact PTH level was significantly higher in patients with hip fracture. The number of remaining teeth was correlated with age, and was also significantly correlated with 25-OHD. In the hip fracture group, 62% of the subjects had hypovitaminosis D (25-OHD <20 ng/ml) and one-fifth of cases with hypovitaminosis D showed elevated PTH levels (>65 pg/ml). On the other hand, in the control group, hypovitaminosis D occurred in 18.9% of the subjects, and only one case showed elevated PTH. The serum 25-OHD level showed a decrease as the severity of dementia progressed and the activity level decreased. Our results indicate that about two-thirds (62%) of hip fracture patients had vitamin D insufficiency, suggesting that this condition may be closely associated with hip fracture in elderly people. Therefore, the serum 25-OHD level may be a useful index for the risk of hip fracture in elderly people.