🔬 Diagnosis & Tests6 min read
Understanding your tests: CT, PFTs, DLCO, and the 6-minute walk
A plain-language guide to the common tests used to understand ILD.
Why this matters
Tests can feel like a foreign language. Knowing what each one looks at helps you follow your own progress and ask informed questions.
The main things to know
- A CT scan shows the pattern and amount of changes in your lungs.
- Breathing tests (PFTs) measure how much air you move and how well oxygen transfers.
- Trends over time usually matter more than any single result.
Visual summary
⬇️ Download infographicHigh-resolution CT scan
A detailed CT scan creates cross-section pictures of your lungs. It helps your team see the pattern of changes, which guides the diagnosis and monitoring.
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Pulmonary function tests (PFTs)
- FVC measures how much air you can breathe out — a common way to follow ILD over time.
- DLCO measures how well oxygen passes from your lungs into your blood.
- These are often repeated at intervals so your team can watch the trend.
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Six-minute walk test (6MWT)
You walk for six minutes while your oxygen level and distance are measured. It shows how your body responds to activity and whether your oxygen drops when you move.
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Reviewed by Dr. Youmna Abdelghany, MD
Pulmonary Disease & Critical Care Medicine
- Last reviewed:
- May 20, 2026
- Next review:
- May 20, 2027
- Reading level:
- Grade 6–8
Sources (3)
- Patient education series — American Thoracic Society (opens a new site)
- Interstitial lung diseases — NHLBI (NIH) (opens a new site)
- Pulmonary fibrosis resources — Pulmonary Fibrosis Foundation (opens a new site)