Abstract
Aim: A characteristic condition of pre-frail elderly people is decreased mobility, which is associated with vitamin D levels and renal function. The aim of this study was to examine the association between physical fitness improvement and vitamin D levels, vitamin D supplements, and renal function in pre-frail elderly people.
Methods: We conducted a longitudinal study in 2 towns from June 2006 to December 2009. Subjects consisted of 177 community-dwelling pre-frail elderly people aged 65 years and over (mean±standard deviation [SD]: 76.4±5.5 yrs) who attended a nursing care prevention program for 3 months. An interview was conducted based on a questionnaire. Serum levels of intact parathyroid hormone (iPTH), 25-hydroxyvitamin D(25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), creatinine, and calcium were measured. eGFR (ml/min/1.73 m2) was calculated using a new formula. Alfacalcidol 1 μg/day was administered to subjects for 3 months, and we assumed that the elderly who took vitamin D (VD) of more than 80% of the recommended daily allowance to be the VD group. Walking ability, balance, and muscle strength physical fitness tests were performed.
Results: The prevalence of eGFR <60.0 ml/min/1.73 m2 was about 24.3%, and that of 25(OH)D <75 nmol/L was 86.4%. Pre-eGFR level and vitamin D supplementation with FR, pre-eGFR and pre 25(OH)D ≥45 nmol/L were associated with improvement in the timed up and go (TUG) test, pre-25(OH)D level (<50 nmol/L, ≥50 nmol/L) was associated with the tandem stance test, pre 25(OH)D level (<67.5 nmol/L, ≥67.5 nmol/L) was associated with the alternate step and 5 chair sit-to-stands tests, and post 1,25(OH)2D (<44 pg/ml, ≥44 pg/ml) was associated with the tandem walk tests.
Conclusions: These results suggest that the assessment of renal function and maintenance of appropriate vitamin D levels are important for the independent living of pre-frail elderly people. Ideally, a 25(OH)D level greater than 67.5 nmol/L is preferable.
