Vitamin D Deficiency is Highly Prevalent in COPD and Correlates with Variants in the Vitamin D Binding Gene.
- Wim Janssens1,*,
- Roger Bouillon2,
- Bart Claes3,
- Claudia Carremans1,
- An Lehouck1,
- Ian Buysschaert3,
- Johan Coolen4,
- Chantal Mathieu2,
- Marc Decramer1,
- Diether Lambrechts3
- 1 Katholieke Universiteit Leuven - Division of Respiratory Medicine, Belgium;
- 2 Katholieke Universiteit Leuven - Laboratory of Endocrinology, Belgium;
- 3 Katholieke Universiteit Leuven - Vesalius Research Center, Belgium;
- 4 Katholieke Universiteit Leuven - Division of radiology, Belgium
- Correspondence to: Wim Janssens, Respiratory Medicine, Katholieke Universiteit Leuven, Herestraat 49, Leuven, 3000, Belgium;
- Received 29 May 2009
- Accepted 21 October 2009
- Published Online First 8 December 2009
Introduction: Vitamin D deficiency has been associated with many chronic illnesses, but little is known about its relation with chronic obstructive pulmonary disease (COPD).
Objectives: We measured serum 25-hydroxyvitamin D levels (25-OHD) in 414 (ex)-smokers older than 50 years and assessed the link between vitamin D status and presence of COPD. 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 COPD patients 25-OHD levels correlated significantly with FEV1 (r = 0.28, p<0.0001). Compared to 31% of the smokers with normal lung function, as much as 60% and 77% of GOLD stage 3 and 4 patients exhibited deficient 25-OHD levels lower than 20ng/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 GOLD stage 3 and 4 patients homozygous for the rs7041 T-allele, exhibited 25-OHD levels lower than 20ng/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: 1.20-3.71; p=0.009).
Conclusion: Vitamin D deficiency occurs frequently in COPD and correlates with severity of COPD. Our data warrant vitamin D supplementation in patients with severe COPD, especially in those carrying at-risk rs7041 variants.