title: Vitamin D status is associated with bone mineral density and functional exercise capacity in patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is associated with several extrapulmonary effects that contribute to the severity of the disease. Vitamin D is suggested to play a role in COPD and its related extrapulmonary effects.
  
  
  OBJECTIVE
  To determine the prevalence of vitamin D deficiency and its relation with bone density, muscle strength, and exercise capacity in patients with COPD.
  
  
  METHODS
  Our cross-sectional study included patients with moderate to very severe COPD. We collected data on lung function, body composition, bone density, quadriceps muscle strength, 6-minute walking distance, and plasma 25-hydroxyvitamin D (25(OH)D) concentration. Vitamin D deficiency was defined as plasma 25(OH)D concentration below 50 nmol/L.
  
  
  RESULTS
  In total, 151 COPD patients were included; 87 patients (58%) had vitamin D deficiency. Plasma 25(OH)D concentration was positively associated with bone density (P = 0.005) and 6-minute walking distance (P < 0.001) after adjustment for potential confounders. Plasma 25(OH)D concentration was not associated with quadriceps muscle strength.
  
  
  CONCLUSIONS
  The majority of COPD patients had vitamin D deficiency. Plasma 25(OH)D concentration was positively associated with bone density and exercise capacity. Intervention studies are necessary to determine whether vitamin D supplementation is of benefit in the prevention or treatment of osteoporosis and poor exercise capacity in patients with COPD.
authors.affiliation: Department of Respiratory Medicine, Catharina Hospital, 5602 ZA Eindhoven, the Netherlands. lisette.romme@cze.nl
authors.forename: Elisabeth A P M
authors.initials: EA
authors.lastname: Romme
authors.forename: Erica P A
authors.initials: EP
authors.lastname: Rutten
authors.forename: Frank W J M
authors.initials: FW
authors.lastname: Smeenk
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Spruit
authors.forename: Paul P C A
authors.initials: PP
authors.lastname: Menheere
authors.forename: Emiel F M
authors.initials: EF
authors.lastname: Wouters
mesh_terms: D000368:Aged; D015519:Bone Density; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D053580:Muscle Strength; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology; D014797:Vital Capacity; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D016138:Walking / Q000502:physiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D