Vitamin D status in kidney transplant patients: need for intensified routine supplementation.
BACKGROUND
A high prevalence of vitamin D insufficiency has been found in the general population and in patients with chronic kidney disease.


OBJECTIVE
The aim was to examine vitamin D status and determinants and metabolic correlates of serum 25-hydroxyvitamin D in a population of adult Danish kidney transplant patients.


METHODS
This was a cross-sectional study of 173 adult kidney transplant patients with a mean (+/-SD) age of 53.4 +/- 11.7 y and a median graft age of 7.4 y (interquartile range: 3.3-12.7 y). Serum concentrations of intact parathyroid hormone (S-PTH), 25-hydroxyvitamin D [S-25(OH)D], and 1,25-dihydroxyvitamin D [S-1,25(OH)(2)D] were measured. Dietary and supplementary intake of vitamin D, avoidance of solar ultraviolet B exposure, and selected lifestyle factors were assessed in a subgroup (n = 97).


RESULTS
Fifty-one percent of the patients had vitamin D insufficiency [S-25(OH)D 40-75 nmol/L], and an additional 29% had moderate-to-severe vitamin D deficiency [S-25(OH)D < or = 39 nmol/L]. In multiple regression analysis, sun avoidance (negative association) and vitamin D supplementation (positive association) were independent determinants of S-25(OH)D concentrations. Low S-25(OH)D concentrations were associated with 1) increased S-PTH concentrations (P = 0.0002), independently of S-1,25(OH)(2)D concentrations, and 2) decreased S-1,25(OH)(2)D concentrations (P = 0.002), independently of graft function.


CONCLUSIONS
Hypovitaminosis D is common among Danish kidney transplant patients and is associated with reduced concentrations of S-1,25(OH)(2)D and increased S-PTH concentrations. Sun avoidance and vitamin D supplementation are important determinants of vitamin D status. The observed hypovitaminosis D might be corrected by intensified routine vitamin D supplementation as opposed to the current supplementation practice.
Ewers
Bettina
B
Department of Nephrology, Copenhagen University Hospital Herlev, Herlev, Denmark.
Gasbjerg
Ane
A
Moelgaard
Christian
C
Frederiksen
Anne Mette
AM
Marckmann
Peter
P
D000328:Adult; D000368:Aged; D002136:Calcium, Dietary / Q000008:administration & dosage; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D016030:Kidney Transplantation; D008019:Life Style; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012044:Regression Analysis; D013472:Sunlight; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
D002136:Calcium, Dietary; D014807:Vitamin D; C104450:25-hydroxyvitamin D