title: Cross-sectional analysis of abnormalities of mineral homeostasis, vitamin D and parathyroid hormone in a cohort of pre-dialysis patients. The chronic renal impairment in Birmingham (CRIB) study.
abstract: BACKGROUND
  Disturbances in mineral and vitamin D metabolism, which affect parathyroid hormone (PTH) synthesis, are well recognized in patients receiving dialysis. However, it is unclear at what stage of chronic kidney disease (CKD) these abnormalities develop.
  
  
  METHODS
  The associations between CKD stages 3 and 5, and alterations of calcium, phosphate, vitamin D and PTH concentrations were assessed in 249 patients (mean age 61 years, 66% male) and 79 age- and sex-matched healthy controls.
  
  
  RESULTS
  As compared to controls, serum phosphate concentrations were elevated among CKD patients (1.40 vs. 1.11 mmol/l; p < 0.0001). And levels of both 25-hydroxyvitamin D (42.1 vs. 60.4 nmol/l; p < 0.0001) and 1,25-dihydroxyvitamin D (58.2 vs. 119.5 pmol/l; p < 0.0001) were lower among patients with CKD, even among those with only stage 3 CKD and despite 73% of patients receiving vitamin D supplements. The ratio of 1,25-dihydroxy- to 25-hydroxyvitamin D was lower than controls, even among patients with stage 3 CKD (p = 0.0001), and this ratio diminished with advancing renal impairment. Concomitant elevations were observed in intact PTH (13.8 vs. 4.2 pmol/l; p < 0.0001) and whole PTH (7.9 vs. 2.7 pmol/l; p < 0.0001).
  
  
  CONCLUSIONS
  Impaired conversion of 25-hydroxy- to 1,25-dihydroxyvitamin D is an early feature of renal disease, and progresses as renal function deteriorates.
authors: Department of Nephrology, University Hospital Coventry and Warwickshire NHS Trust, Coventry, UK. d.zehnder@warwick.ac.uk
authors: Daniel
authors: D
authors: Zehnder
authors: Martin J
authors: MJ
authors: Landray
authors: David C
authors: DC
authors: Wheeler
authors: William
authors: W
authors: Fraser
authors: Lisa
authors: L
authors: Blackwell
authors: Sarah
authors: S
authors: Nuttall
authors: Sue V
authors: SV
authors: Hughes
authors: John
authors: J
authors: Townend
authors: Charles
authors: C
authors: Ferro
authors: Colin
authors: C
authors: Baigent
authors: Martin
authors: M
authors: Hewison
mesh_terms: D000368:Aged; D002118:Calcium / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006706:Homeostasis; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood* / Q000209:etiology; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000150:complications / Q000534:rehabilitation; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood*; D010710:Phosphates / Q000097:blood*; D006435:Renal Dialysis / Q000009:adverse effects*; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000209:etiology
chemical_list: D008903:Minerals; D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; D002118:Calcium