17th February 2025

Diagnosis of COPD

Typical investigation findings include the following:

Blood tests: FBC and CRP to identify anaemia and secondary polycythaemia, and rule out infection
Chest X-ray: flattened diaphragm, hyperexpanded lungs, bullae
Lung function tests, especially post-bronchodilator spirometry, which should show an obstructive picture (FEV1/FVC <70%) to be in keeping with a diagnosis of COPD
BMI: low BMI or weight loss is common in severe COPD and associated with a worse prognosis. It can also be associated with a co-existing lung cancer

Image Source: Wikimedia Commons (2010). COPD, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:COPD.JPG (Accessed: 19 January 2024).

FEV₁ is used to determine the severity of COPD:


>80% of predicted	Stage 1: mild COPD – should have symptoms, e.g. cough or breathlessness, to make diagnosis
50-80% of predicted	Stage 2: moderate COPD
30-50% of predicted	Stage 3: severe COPD
<30% of predicted	Stage 4: very severe COPD

Table 3 Staging of COPD using FEV₁

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