title: Plasma Vitamin D Level and Change in Albuminuria and eGFR According to Sodium Intake.
abstract: OBJECTIVE
  Low circulating 25-hydroxyvitamin D [25(OH)D] and high sodium intake are both associated with progressive albuminuria and renal function loss in CKD. Both vitamin D and sodium intake interact with the renin-angiotensin-aldosterone system. We investigated whether plasma 25(OH)D or 1,25-dihydroxyvitamin D [1,25(OH)2D] is associated with developing increased albuminuria or reduced renal function and whether these associations depend on sodium intake.
  
  
  METHODS
  Baseline plasma 25(OH)D and 1,25(OH)2D were measured by liquid chromatography tandem mass spectrometry, and sodium intake was assessed by 24-hour urine collections in the general population-based Prevention of Renal and Vascular End-Stage Disease cohort (n=5051). Two primary outcomes were development of urinary albumin excretion >30 mg/24 h and eGFR (creatinine/cystatin C-based CKD Epidemiology Collaboration) <60 ml/min per 1.73 m(2). Participants with CKD at baseline were excluded. In Cox regression analyses, we assessed associations of vitamin D with developing increased albuminuria or reduced eGFR and potential interaction with sodium intake.
  
  
  RESULTS
  During a median follow-up of 10.4 (6.2-11.4) years, 641 (13%) participants developed increased albuminuria, and 268 (5%) participants developed reduced eGFR. Plasma 25(OH)D was inversely associated with increased albuminuria (fully adjusted hazard ratio [HR] per SD higher, 0.86; 95% confidence interval [95% CI], 0.78 to 0.95; P=0.003) but not reduced eGFR (HR, 0.99; 95% CI, 0.87 to 1.12; P=0.85). There was interaction between 25(OH)D and sodium intake for risk of developing increased albuminuria (P interaction =0.03). In participants with high sodium intake, risk of developing increased albuminuria was inversely associated with 25(OH)D (lowest versus highest quartile: adjusted HR, 1.81; 95% CI, 1.20 to 2.73, P<0.01), whereas this association was nonsignificant in participants with low sodium intake (HR, 1.29; 95% CI, 0.94 to 1.77; P=0.12). Plasma 1,25(OH)2D was not significantly associated with increased albuminuria or reduced eGFR.
  
  
  CONCLUSIONS
  Low plasma 25(OH)D is associated with higher risk of developing increased albuminuria, particularly in individuals with high sodium intake, but not of developing reduced eGFR. Plasma 1,25(OH)2D is not associated with risk of developing increased albuminuria or reduced eGFR.
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and.
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Keyzer
authors.affiliation: Departments of Clinical Pharmacy and Pharmacology and.
authors.forename: Hiddo J
authors.initials: HJ
authors.lastname: Lambers-Heerspink
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Michel M
authors.initials: MM
authors.lastname: Joosten
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and.
authors.forename: Petronella E
authors.initials: PE
authors.lastname: Deetman
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and.
authors.forename: Ron T
authors.initials: RT
authors.lastname: Gansevoort
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and.
authors.forename: Gerjan
authors.initials: G
authors.lastname: Navis
authors.affiliation: Laboratory Medicine, University of Groningen, University Medical Center Groningen, The Netherlands; and.
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
authors.affiliation: Departments of Clinical Pharmacy and Pharmacology and.
authors.forename: Dick
authors.initials: D
authors.lastname: de Zeeuw
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Stephan J L
authors.initials: SJ
authors.lastname: Bakker
authors.affiliation: Department of Internal Medicine, Division of Nephrology, and m.h.de.borst@umcg.nl.
authors.forename: Martin H
authors.initials: MH
authors.lastname: de Borst
mesh_terms: D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D002853:Chromatography, Liquid; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009426:Netherlands; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000009:adverse effects* / Q000652:urine; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D016482:Urinalysis; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000175:diagnosis
chemical_list: D015415:Biomarkers; D012982:Sodium, Dietary; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D
keywords: 1,25-dihydroxyvitamin D; 25-hydroxyvitamin D; albuminuria; chronic kidney disease; creatinine; cystatin C; diet; eGFR; follow-up studies; humans; sodium; vitamin D