Hypovitaminosis D and hyperparathyroidism in physically inactive elderly Japanese living in nursing homes: relationship with age, sunlight exposure and activities of daily living.

Abstract

The purposes of this study were to investigate the prevalences of hypovitaminosis D and hyperparathyroidism in physically inactive elderly people living in Japanese nursing homes and determine any correlations with demographic, environmental and/or life-style factors. We targeted 220 elderly people living in nursing homes for the physically disabled in Japan. Of these, 133 (women, 113; men, 20) subjects who agreed and met our inclusion criteria were studied. The average age of the subjects was 84.6 years (SD 8.2). Serum 25-hydroxyvitamin D3 (25[OH]D3), intact parathyroid hormone (intact PTH), creatinine, and albumin concentrations were measured in each subject. Total hours of sunshine during the previous 5 weeks, activities of daily living (ADL) levels, and dietary vitamin D intake were also measured. ADL levels were evaluated using the Physical Self-Maintenance Scale (5-point scale). The examinations were performed between October and December, 1999. The average concentrations of serum 25(OH)D3 and intact PTH were 29.9 nmol/L (SD 13.1) and 5.04 pmol/L (SD 2.27), respectively. The prevalences of hypovitaminosis D (25[OH]D3<30 nmol/L) and hyperparathyroidism (intact PTH>6.90 pmol/L) were 77/133 (57.9%) and 21/133 (15.8%), respectively. Serum 25(OH)D3 concentrations were positively associated with hours of sunshine (R2=0.371, p<0.001) and serum albumin concentrations (R2=0.086, p<0.001), but not with age (p=0.075) or total ADL score (p=0.527). A negative association between serum intact PTH and 25(OH)D3 levels was found in subjects who were 80 years or older (p<0.001) but not in subjects under the age of 80 years. Hypovitaminosis D and hyperparathyroidism are commonly seen in elderly Japanese with low ADL levels. Hypovitaminosis D seems to adversely affect PTH levels, especially in the very elderly.