title: The association between vitamin D and C-reactive protein levels in patients with inflammatory and non-inflammatory diseases.
abstract: OBJECTIVE
  A direct, inverse correlation between 25-hydroxy vitamin D (25(OH) vitamin D) levels and C-reactive protein (CRP), a sensitive biomarker for inflammation, was found in some, but not all, studies. These effects were seen in healthy subjects as well as in some inflammatory diseases.
  
  
  METHODS
  CRP and 25(OH) vitamin D data (2011-2013) from 923 in- and outpatients (males/females 340/583; median age: 76years (95% confidence interval (CI): 75-77) were analyzed. A standardized diagnosis according to the Dutch diagnosis coding standard for each patient was obtained. Each diagnosis was categorized as either inflammatory or non-inflammatory disease. Analysis of variance was performed with age, gender, inflammatory status (inflammatory disease/non-inflammatory disease), and season as corrective factors.
  
  
  RESULTS
  The correlation between (log) ln-25(OH) vitamin D and ln-CRP was highly significant (p<0.001) with a regression coefficient of -0.879. In the inflammatory disease group, the R(2) value was 0.726 and in the non-inflammatory disease group it was 0.502. It was shown that increasing 25(OH) vitamin D levels are associated with decreasing CRP levels, with a stronger effect in the inflammatory disease group compared to the non-inflammatory disease group.
  
  
  CONCLUSIONS
  Our study shows an inverse correlation between 25(OH) vitamin D and CRP in a large patient cohort but more importantly shows that this effect is more pronounced in patients with inflammatory diseases compared to patients with non-inflammatory diseases.
authors.affiliation: Medical laboratory, Nij Smellinghe Hospital, Compagnonsplein 1, 9209 NN Drachten, the Netherlands. Electronic address: a.kruit@nijsmellinghe.nl.
authors.forename: Adrian
authors.initials: A
authors.lastname: Kruit
authors.affiliation: Department of Pulmonology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, the Netherlands. Electronic address: p.zanen@umcutrecht.nl.
authors.forename: Pieter
authors.initials: P
authors.lastname: Zanen
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D002097:C-Reactive Protein / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007159:Immunologic Tests; D007249:Inflammation / Q000097:blood / Q000175:diagnosis*; D008297:Male; D011379:Prognosis; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; D002097:C-Reactive Protein; C104450:25-hydroxyvitamin D
keywords: 25(OH) vitamin D; C-reactive protein; Inflammation