The main objective is to study important factors in the patho-physiology of osteoporosis in patients with COPD. Therefore, the investigators will study biological markers in plasma and urine and correlate them to markers of bone turnover and clinical data.

Rationale:

Chronic obstructive pulmonary disease (COPD) is defined as a preventable and treatable disease with significant extrapulmonary effects. Osteoporosis is recognized as one of these extrapulmonary consequences. It results in increased risk of fracture and thereby an increased morbidity and mortality. Nowadays it is believed that the patho-physiology of osteoporosis is multi-factorial. However, which factors are most important in patients with COPD is still not clear.

Objective:

The main objective is to study important factors in the patho-physiology of osteoporosis in patients with COPD. Therefore, we will study biological markers in plasma and urine and correlate them to markers of bone turnover and clinical data.

Study design:

The present study will be an observational, cross-sectional study.

Inclusion Criteria for the COPD patients:

• Aged 50 years or older;
• Women have to be postmenopausal (amenorrhea for 12 months or more)
• COPD Global initiative of Obstructive Lung Disease (GOLD) I, II, III and IV according to the American Thoracic Society (ATS) guidelines;
• ≥ 12 pack years;
• No respiratory tract infection or exacerbation of the disease for at least 4 weeks before the study;
• No use of oral corticosteroids for at least 4 weeks before the study;
• No use of anti-osteoporotic medication (calcium, vitamin D, biphosphonates) before inclusion;
• Capable to provide informed consent.

Exclusion Criteria for the COPD patients:

• Malignancy in the last 5 years;
• Lung fibrosis;
• Inflammatory bowel disease;
• Rheumatoid arthritis;
• Alcohol abuse;
• Bronchiectasia;
• Auto immune diseases;
• Hypothyroidism or hyperthyroidism based on blood sampling for thyroid hormone (TSH, fT4).

In total 120 patients will be included. All subjects will be included from the outdoor clinic of the department of Pulmonology of the Catharina Hospital Eindhoven or Diagnostic Centre Eindhoven (DCE). The subjects are divided into 6 groups of 20 subjects each, I: COPD patients with osteoporosis based on T-score and without vertebral fractures, II: COPD patients with osteoporosis based on T-score and vertebral fractures, III: COPD patients with vertebral fractures and without osteoporosis based on T-score, IV: COPD patients without osteoporosis based on T-score and without vertebral fractures, V: healthy controls with osteoporosis based on T-score and without vertebral fractures, VI: healthy controls without osteoporosis based on T-score and without vertebral fractures.