Association of 1,25-dihydroxyvitamin D levels with physical performance and thigh muscle cross-sectional area in chronic kidney disease stage 3 and 4.
BACKGROUND
Declines in 1,25-dihydroxyvitamin D (1,25(OH)₂D) levels and physical functioning follow the course of chronic kidney disease (CKD). Although the molecular actions of vitamin D in skeletal muscle are well known, and muscle weakness and atrophy are observed in vitamin D-deficient states, there is little information regarding vitamin D and muscle function and size in CKD.


OBJECTIVE
To examine associations of vitamin D with physical performance (PF) and muscle size.


METHODS
Cross-sectional.


METHODS
CKD clinic.


METHODS
Twenty-six patients (61 ± 13 years, 92% men) with CKD stage 3 or 4.


METHODS
Gait speed, 6-minute walk, sit-to-stand time, 1-legged balance, and thigh muscle cross-sectional area (MCSA), measured by magnetic resonance imaging (MRI).


RESULTS
Overall, 73% were 25-hydroxyvitamin D (25(OH)D) deficient (n = 10) or insufficient (n = 9) (Kidney Disease Outcomes Quality Initiative guidelines). 25(OH)D level was associated with normal gait speed only (r = 0.41, P = .04). Normal and fast gait speed, the distance walked in 6 minutes, and sit-to-stand time were best explained by 1,25(OH)₂D and body mass index (P < .05 for all) and 1-legged stand by 1,25(OH)₂D (r = 0.40, P < .05) only. There were no associations of age, estimated glomerular filtration rate (eGFR), intact parathyroid hormone (iPTH), or albumin with any PF measures. MCSA was associated with eGFR (r = 0.54, P < .01) only. Variance in MCSA was best explained by a model containing 1,25(OH)₂D, plasma Ca²⁺, and daily physical activity (by accelerometry) (P < .05 for all). Once these variables were in the model, there was no contribution of eGFR.


CONCLUSIONS
These results suggest that 1,25(OH)₂D is a determinant of PF and muscle size in patients with stage 3 and 4 CKD.
Division of Nephrology, Department of Medicine, University of California, San Francisco, California 94121, USA. patricia.gordon@ucsf.edu
Patricia L
PL
Gordon
Julie W
JW
Doyle
Kirsten L
KL
Johansen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019412:Anatomy, Cross-Sectional; D002118:Calcium / Q000097:blood; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D010281:Parathyroid Hormone / Q000097:blood; D012044:Regression Analysis; D012709:Serum Albumin / Q000032:analysis; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000503:physiopathology
D010281:Parathyroid Hormone; D012709:Serum Albumin; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; D002118:Calcium