Aims: Vitamin D stores in dialysis patients may be associated with their muscle function and physical performance. We analyzed associations of 25-hydroxyvitamin D levels with functional test results in prevalent hemodialysis patients and healthy controls.
Methods: Study sample included 54 dialysis patients and 81 healthy controls who performed a 6-minute walk test, sit-to-stand test, handgrip strength measurement, and self-rated habitual adjusted activity score with Human Activity Profile questionnaire. Adjusted general linear models were used to analyze association of 25-hydroxyvitamin D levels with test results.
Results: Serum 25-hydroxyvitamin D concentration was 73.1 ± 35.4 nmol/L in dialysis patients and 64.6 ± 22 nmol/L in controls (p = 0.12). When adjusted for age, sex, body height, spontaneous gait speed, and dialysis dependence, 25-hydroxyitamin D was significantly positively associated with 6-minute walk test result, explaining 5% of variability in walked distance (B = 0.6 m/nmol/L, p = 0.008) and 12% of variability in adjusted activity score (B = 0.1 point/nmol/L, p < 0.001). There was no significant association with handgrip strength or sit-to-stand performance in adjusted models.
Conclusions: Serum 25-hydroxyvitamin D levels are significantly positively associated with submaximal aerobic physical performance and habitual activity level in dialysis patients. .