title: The relationship between the level of serum 25-hydroxyvitamin D and renal function in patients without chronic kidney disease: a cross-sectional study.
abstract: OBJECTIVE
  Low level of vitamin D has been suggested as a risk factor for chronic kidney disease (CKD). However, little is known about the effect of vitamin D on renal function in healthy subjects. Our aim was to investigate the question of whether vitamin D status is associated with renal function in subjects without CKD.
  
  
  METHODS
  In this cross-sectional study, 1,648 subjects aged older than 20 years were recruited as study participants. Subjects diagnosed with either CKD or other conditions that could influence serum vitamin D were excluded. Estimated glomerular filtration rate (eGFR) from serum creatinine (sCr) was used for the determination of renal function. Vitamin D status was determined by the measurement of serum 25-hydroxyvitamin D [25(OH)D] levels.
  
  
  RESULTS
  In men, 25(OH)D showed significant positive correlation with age (r = 0.127, P < .001), skeletal muscle mass (r = 0.077, P = .017), sCr (r = 0.128, P < .001), and negative correlation with body fat (r = -0.065, P = .044), eGFR (r = -0.152, P < .001). In women, 25(OH)D showed negative correlation with eGFR (r = -0.085, P = .026), but not with age and body composition. In multiple linear regression analysis, 25(OH)D (β = 0.114, P < .001), total muscle mass (β = 0.202, P = .026), and age (β = 0.117, P = .003) were an independent determinant of sCr in men; in women, 25(OH)D (β = 0.086, P = .023), total muscle mass (β = 0.152, P < .001) were variables showing significant association with sCr.
  
  
  CONCLUSIONS
  Higher level of 25(OH)D is independently associated with sCr elevation. We suggest that a positive correlation between 25(OH)D and muscle mass could be attributed to sCr. It is thought to be another mechanism of serum 25(OH)D level in renal function in populations without CKD.
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Tak
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea. Electronic address: jeklee@pusan.ac.kr.
authors.forename: Jeong Gyu
authors.initials: JG
authors.lastname: Lee
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Department of Internal Medicine, Pusan National University School of Medicine, Busan, Republic of Korea.
authors.forename: Sang Heon
authors.initials: SH
authors.lastname: Song
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Yun Jin
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Medical Education Unit, Pusan National University School of Medicine, Yangsan, Republic of Korea.
authors.forename: Sangyeoup
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea.
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Jung
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Yu Hyeon
authors.initials: YH
authors.lastname: Yi
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea.
authors.forename: Young Hye
authors.initials: YH
authors.lastname: Cho
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Choi
authors.affiliation: Department of Family Medicine, Pusan National University School of Medicine, Busan, Republic of Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Hye Rim
authors.initials: HR
authors.lastname: Hwang
mesh_terms: D000367:Age Factors; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D