Vitamin D deficiency is highly prevalent in COPD and correlates with variants in the vitamin D-binding gene.
BACKGROUND
Vitamin D deficiency has been associated with many chronic illnesses, but little is known about its relationship with chronic obstructive pulmonary disease (COPD).


OBJECTIVE
Serum 25-hydroxyvitamin D (25-OHD) levels were measured in 414 (ex)-smokers older than 50 years and the link between vitamin D status and presence of COPD was assessed. The rs7041 and rs4588 variants in the vitamin D-binding gene (GC) were genotyped and their effects on 25-OHD levels were tested.


RESULTS
In patients with COPD, 25-OHD levels correlated significantly with forced expiratory volume in 1 s (FEV(1)) (r=0.28, p<0.0001). Compared with 31% of the smokers with normal lung function, as many as 60% and 77% of patients with GOLD (Global Initiative for Obstructive Lung Disease) stage 3 and 4 exhibited deficient 25-OHD levels <20 ng/ml (p<0.0001). Additionally, 25-OHD levels were reduced by 25% in homozygous carriers of the rs7041 at-risk T allele (p<0.0001). This correlation was found to be independent of COPD severity, smoking history, age, gender, body mass index, corticosteroid intake, seasonal variation and rs4588 (p<0.0001). Notably, 76% and 100% of patients with GOLD stage 3 and 4 homozygous for the rs7041 T allele exhibited 25-OHD levels <20 ng/ml. Logistic regression corrected for age, gender and smoking history further revealed that homozygous carriers of the rs7041 T allele exhibited an increased risk for COPD (OR 2.11; 95% CI 1.20 to 3.71; p=0.009).


CONCLUSIONS
Vitamin D deficiency occurs frequently in COPD and correlates with severity of COPD. The data warrant vitamin D supplementation in patients with severe COPD, especially in those carrying at-risk rs7041 variants.
Janssens
Wim
W
Respiratory Division, University Hospital Gasthuisberg, KUL Herestraat 49, 3000 Leuven, Belgium. wim.janssens@uz.kuleuven.be
Bouillon
Roger
R
Claes
Bart
B
Carremans
Claudia
C
Lehouck
An
A
Buysschaert
Ian
I
Coolen
Johan
J
Mathieu
Chantal
C
Decramer
Marc
M
Lambrechts
Diether
D
D000368:Aged; D005260:Female; D005541:Forced Expiratory Volume; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology; D012720:Severity of Illness Index; D014797:Vital Capacity; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000235:genetics; D014808:Vitamin D Deficiency / Q000150:complications* / Q000235:genetics / Q000503:physiopathology; D014809:Vitamin D-Binding Protein / Q000235:genetics*
D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D