Patients with COPD have been found to have an increased risk of osteoporosis. The underlying mechanism is not clear yet. This case control study aims to identify risk factors for osteoporosis in GOLD II COPD patients. COPD GOLD II patients with osteoporosis (cases) will be matched by gender and age to COPD GOLD II patients without osteoporosis(controls).

Possible risk factors for osteoporosis are:

• BMI/VVMI (body composition)
• emphysema vs chronic bronchitis
• physical capacity
• Use of certain medication (eg corticosteroids, SSRI's)
• Nutritional status
• Infectious parameters Outpatients from the pulmonary ward of the Catharina Hospital Eindhoven with GOLD II COPD according to the ATS and GOLD-guidelines will be included in the study (after written informed consent).

A DEXA-scan will be made, if patients are osteoporotic or have a normal BMD they will be included in the study.

A HRCT will be made, a six minutes walking distance will be performed, blood will be drawn for lab. analysis, an X-ray of the vertebral collum will be made, impedance will be measured and hight and weight will be measuered. Also patients will fill in a questionaire.

By univariate and multivariate analysis the collected data will be analysed to determine possible risk factors for th development of osteoporosis in COPD GOLD II patients.

Inclusion Criteria:

• Age >= 40 years
• GOLD II COPD
• Written permission

Exclusion Criteria:

• Age < 40 years
• No COPD or COPD GOLD I, III or IV
• no written permission

GOLD II COPD patients (ATS and GOLD guidelines) visiting the outpatient clinic of pulmonary medicine of the Catharina Hospital Eindhoven.