Lung Function Tests (Spirometry and Full PFTs)

Lung function tests measure how much air your lungs hold, how fast you can blow it out, and how well oxygen passes from the lungs into the blood. The basic test is spirometry. A full set adds lung volumes, gas transfer (DLCO) and sometimes a challenge or exercise test.

They are the main way to diagnose and grade asthma and COPD, to detect scarring or restrictive lung disease, and to judge whether someone is fit for lung surgery or a major anaesthetic. They measure function, not structure, so they complement a chest X-ray or CT rather than replace it.

What Lung Function Tests (Spirometry and Full PFTs) shows

Spirometry gives the forced vital capacity (FVC), the volume blown out in the first second (FEV1) and their ratio. A low ratio indicates airway obstruction, as in asthma or COPD. Improvement after an inhaled bronchodilator points towards asthma. A low FVC with a normal ratio suggests restriction, which is confirmed by measuring total lung capacity in a body box (plethysmography). Gas transfer falls in emphysema, pulmonary fibrosis, pulmonary vascular disease and anaemia. FeNO, a measure of exhaled nitric oxide, reflects allergic airway inflammation. Results are compared with predicted values for your age, height and sex.

When Lung Function Tests (Spirometry and Full PFTs) is recommended

• Persistent cough, wheeze or breathlessness without a clear cause
• Suspected or known asthma or COPD, to confirm the diagnosis and track severity
• Smokers and ex-smokers over about 40 with symptoms
• Before lung resection, major chest or upper abdominal surgery, and often before bariatric surgery
• Monitoring of interstitial lung disease, sarcoidosis, neuromuscular disease or the effect of certain drugs
• Occupational dust or chemical exposure

Limits and situations where another test is better:

• Normal results at rest do not exclude asthma, which varies from day to day; a challenge test or peak flow diary may be needed
• They cannot show tumours, clots or infection, which need imaging
• Young children under about 5 usually cannot perform the manoeuvres reliably
• Testing is postponed after a recent heart attack, pneumothorax, eye or abdominal surgery, or while coughing blood

How to prepare

• Wear loose clothing and avoid a heavy meal in the 2 hours before
• Do not smoke on the day and avoid vigorous exercise for an hour beforehand
• Ask which inhalers to withhold, commonly short-acting relievers for 4 to 6 hours and long-acting ones for 12 to 24 hours
• Bring a list of your medicines and any earlier results

What happens during the test

You sit upright with a nose clip on and seal your lips around a mouthpiece. For spirometry you breathe in fully and blast the air out as hard and as long as you can, at least three times. For lung volumes you sit in a clear cabin and pant gently against a shutter. For gas transfer you inhale a test gas, hold your breath for about 10 seconds and breathe out. A full set takes 45 to 60 minutes. It is tiring and can make you light-headed or set off coughing.

Results and next steps

The numbers are available immediately and a respiratory physician normally interprets them the same day or the next. The report grades any obstruction or restriction and compares with previous tests. Depending on the pattern, the next step may be an inhaler trial, a CT scan, an echocardiogram, a walking or cardiopulmonary exercise test, or clearance for surgery.

• Test time: 15 minutes for spirometry, 45 to 60 minutes for a full set
• Results ready: Same day
• Back to everyday activity: None

Safety and risks

• Dizziness or brief faintness from forced breathing
• Coughing or wheeze, especially during a bronchial challenge test, which is reversed with a reliever inhaler
• Chest muscle soreness afterwards
• Very rarely, pneumothorax in people with severe bullous lung disease

Arranging Lung Function Tests (Spirometry and Full PFTs) in Türkiye

There is no reason to travel for these tests alone, as they are available nearly everywhere. They are useful as part of a respiratory second opinion, a smoker's check-up, or the pre-operative assessment for surgery you are already having in Istanbul. Bring earlier results so that change over time can be judged.

Send your previous reports and the question you want answered and a Clinic-Y coordinator replies within 24 hours with suitable teams and written, all-inclusive proposals side by side. Reviewing your case is free.

Frequently Asked Questions