Serum 25-hydroxyvitamin D levels and activities of daily living in noninstitutionalized elderly Japanese requiring care

Abstract

To date, no study has investigated the nutritional status of vitamin D in frail elderly people living at home. The purposes of this study were to assess serum 25-hydroxyvitamin D (25[OH]D) levels and associated factors in noninstitutionalized elderly people who had various levels of physical disability, and to propose an adequate vitamin D nutritional status for the elderly by interpreting the serum 25(OH)D levels in relation to serum parathyroid hormone (PTH) levels in this population. Health examinations were conducted in the winter and summer of 2003. The subjects were 143 elderly people in the winter, and 120 elderly people in the summer, who all used the long-term care insurance system at home. Serum 25(OH)D concentrations were determined with a chemiluminescence protein-binding assay, and serum intact PTH concentrations were determined with an immunoradiometric assay. The subjects' disease histories and lifestyle information were obtained through an interview. Activities of daily living (ADL) levels were evaluated using the Barthel index, and grip strength was measured with a digital hand dynamometer. Average serum 25(OH)D levels in the winter and summer were 54.2 nmol/l (SD 29.0) and 53.3 nmol/l (SD 32.3), respectively, and intact PTH concentrations in the winter and summer were 4.2 pmol/l (SD 1.8) and 4.3 pmol/l (SD 1.8), respectively. The proportion of people who had a low 25(OH)D (<30 nmol/l) and high intact PTH levels (>6.9 pmol/l) were 15%-20% and 8%, respectively. Significant predictors of low serum 25(OH)D concentrations were low ADL levels, female sex, and low fish consumption in both seasons. Serum 25(OH)D concentrations of less than 50 nmol/l were associated with elevated serum intact PTH concentrations. In conclusion, elderly people requiring care at home are at high risk of hypovitaminosis D, and their low serum 25(OH)D levels are mainly associated with low ADL levels. In addition, maintenance of serum 25(OH)D concentrations above 50 nmol/l may prevent hypovitaminosis D-induced hyperparathyroidism.

Associations of Daily Walking Steps with Calcaneal Ultrasound Parameters and a Bone Resorption Marker in Elderly Japanese Women

“…Lower levels of serum 25[OH]D directly increase PTH levels, which can accelerate bone turnover in the elderly (Chapuy et al, 1996). Nakamura et al (2005) demonstrated a clear association between serum 25[OH]D levels and activities of daily living (ADL) in elderly Japanese. As a more likely explanation for this relationship, they speculated that elderly people with a higher ADL frequently go out and have sufficient ultraviolet exposure, which leads to increased vitamin D synthesis in the skin.…”

Concomitant Lower Serum Albumin and Vitamin D Levels Are Associated with Decreased Objective Physical Performance among Japanese Community-Dwelling Elderly

“…Although the results of some Japanese studies offer suggestions, the cutoff value for elderly Japanese is still uncertain. For example, serum 25OHD concentrations of less than 30.0 [19] , 40.0 [20] or 50.0 nmol/l [21] were defined as cutoff values for vitamin D insufficiency. Therefore, we summarized the serum albumin and 25OHD levels of these subjects into quartiles, and use the 25 percentile cutoff to classify the subjects into higher versus lower albumin and 25OHD groups.…”

Independent Association of Vitamin D With Physical Function in People With Chronic Spinal Cord Injury

“…[16][17][18][19] This link has been further corroborated by the results of a meta-analysis of randomized controlled trials, which provided the evidence of a fall preventive effect exerted by high dose vitamin D supplementation. 20 However, when cross-sectional and longitudinal studies have explored the independent association of vitamin D levels with composite outcomes of physical function and muscle performance, results became more contradictory: such an association was supported by some studies [21][22][23][24][25][26][27][28][29][30] but not by others. 16,[31][32][33] A high prevalence of vitamin D deficiency has been reported in patients with chronic spinal cord injury (SCI).…”