Diagnosis & Lung Function Testing

Lung Disease - Diagnosis & Lung Function Testing

Diagnosing lung disease often requires more than one test because many respiratory conditions cause similar symptoms. Chronic cough, wheezing, fatigue, chest discomfort, and shortness of breath may occur in several lung diseases as well as heart conditions, infections, anaemia, and other medical problems.

The diagnostic process aims to determine which part of the respiratory system is affected, identify the underlying cause, assess severity, and guide an appropriate treatment plan.

Medical and Exposure History

The evaluation usually begins with a detailed discussion of the patient’s symptoms and medical history.

A healthcare professional may ask:

• When symptoms began
• Whether they are worsening
• What triggers or relieves them
• Whether there is mucus or blood
• Whether infections frequently occur
• Whether the patient smokes or previously smoked
• Whether there is exposure to second-hand smoke
• Which jobs the patient has performed
• Whether the patient has worked around dust, fumes, fibres, or chemicals
• Whether there is mould, dampness, or poor ventilation at home
• Whether birds, animals, or agricultural materials are present
• Which medications the patient uses
• Whether other family members have lung disease

Occupational and environmental information is especially important because some exposures can contribute to asthma, COPD, interstitial lung disease, and lung cancer.

Physical Examination

During the examination, the healthcare professional may observe how the patient breathes, assess breathing rate, listen to the lungs, and measure oxygen saturation.

The examination may identify wheezing, crackling sounds, reduced airflow, abnormal breathing patterns, swelling, cyanosis, or changes in the fingertips.

Physical findings can support a diagnosis but often need to be combined with objective testing.

Spirometry

Spirometry is one of the most commonly used lung function tests. It measures how much air a person can breathe out and how quickly the air can be expelled.

The patient usually takes a deep breath and blows forcefully into a mouthpiece connected to a spirometer. The test may be repeated several times to produce reliable measurements.

Spirometry can help identify airflow obstruction and may be used when asthma or COPD is suspected. A bronchodilator may be given during testing to determine whether airflow improves after medication.

Complete Pulmonary Function Tests

A complete pulmonary function assessment may include several measurements:

• Spirometry
• Lung volumes
• Diffusion capacity
• Airway resistance
• Bronchodilator response
• Respiratory muscle strength

Lung-volume testing measures how much air the lungs can contain and how much remains after exhalation. Diffusion testing evaluates how effectively gases move from the lungs into the bloodstream.

These tests may help distinguish obstructive diseases from restrictive diseases and assess the severity of functional impairment.

Peak Flow Monitoring

A peak-flow meter measures how quickly a person can breathe air out. It is often used by people with asthma to monitor changes in airflow at home.

Regular measurements may help identify deterioration before symptoms become severe. However, peak-flow monitoring does not replace formal diagnostic testing or medical assessment.

Exercise and Walking Tests

Some patients undergo exercise testing to assess how the lungs, heart, circulation, and muscles respond to physical activity.

A six-minute walk test may measure:

• Walking distance
• Oxygen saturation
• Heart rate
• Breathlessness
• Exercise tolerance

More advanced cardiopulmonary exercise testing may be used when the cause of breathlessness remains unclear or when preparing for major surgery.

Chest X-Ray

A chest X-ray provides an image of the lungs, heart, airways, ribs, and surrounding structures.

It may show pneumonia, fluid around the lungs, a collapsed lung, a mass, advanced fibrosis, or other abnormalities. However, some early or subtle lung diseases may not be visible on a standard X-ray.

A normal X-ray does not rule out all respiratory conditions.

Computed Tomography

Computed tomography, commonly known as a CT scan, provides more detailed cross-sectional images of the chest.

A high-resolution CT scan may be particularly useful for evaluating pulmonary fibrosis, bronchiectasis, emphysema, small nodules, occupational lung disease, and other structural abnormalities.

CT imaging may also guide biopsy procedures, treatment planning, or follow-up of previously identified findings.

Blood and Oxygen Tests

Blood tests may help identify infection, inflammation, autoimmune disease, allergy, genetic conditions, or other causes of respiratory symptoms.

Pulse oximetry estimates oxygen saturation using a sensor placed on the finger. Arterial blood gas testing directly measures oxygen, carbon dioxide, and blood acidity.

These tests may be particularly important in severe disease, respiratory failure, or when evaluating the need for oxygen therapy.

Sputum Testing

A sample of mucus may be examined when infection, tuberculosis, fungal disease, or abnormal cells are suspected.

The sample may be tested using microscopy, culture, molecular methods, or cytology. Results can help identify an infectious organism and determine which treatment may be effective.

Bronchoscopy

Bronchoscopy allows a specialist to view the airways using a thin flexible tube equipped with a light and camera.

The procedure may be used to:

• Investigate bleeding
• Examine airway narrowing
• Remove foreign material
• Collect fluid or tissue samples
• Evaluate a suspected tumour
• Diagnose infection
• Perform certain treatments

Bronchoscopy is generally performed with local anaesthesia, sedation, or general anaesthesia, depending on the procedure.

Lung Biopsy

A biopsy involves removing a small sample of lung or lymph-node tissue for examination.

Samples may be obtained through bronchoscopy, a needle guided by imaging, minimally invasive surgery, or another technique.

Biopsy may be needed when imaging and other tests cannot provide a definite diagnosis. It is particularly important in some cases of cancer, pulmonary fibrosis, autoimmune disease, or unexplained lung abnormalities.

Genetic and Molecular Testing

Genetic testing may be used when cystic fibrosis, alpha-1 antitrypsin deficiency, hereditary pulmonary hypertension, or another inherited condition is suspected.

Molecular testing is also increasingly used in lung cancer to identify changes that may guide targeted treatment.

Establishing Disease Severity

Diagnosis is not limited to naming the condition. Healthcare professionals also assess how much the disease affects lung function, oxygen levels, physical activity, and quality of life.

Severity assessment may include:

• Lung function measurements
• Imaging findings
• Symptom frequency
• Number of flare-ups
• Oxygen saturation
• Exercise capacity
• Hospital admissions
• Effect on everyday activities

An accurate assessment helps determine whether the patient requires medication, rehabilitation, oxygen, surgery, specialist follow-up, or other treatment.

Seeking a Second Opinion

A second specialist opinion may be useful when the diagnosis is uncertain, symptoms continue despite treatment, surgery is recommended, or the condition is rare or complex.

Patients should collect relevant medical records, including:

• Imaging files
• Radiology reports
• Lung function results
• Blood-test results
• Pathology findings
• Bronchoscopy reports
• Medication lists
• Previous treatment plans

International patients seeking evaluation abroad should determine whether the hospital has access to pulmonology, radiology, pathology, thoracic surgery, oncology, and intensive-care services when these specialties may be required.

Diagnosis should be based on the patient’s complete clinical picture rather than a single test result. Combining symptoms, history, examination, imaging, lung function measurements, and laboratory findings allows healthcare professionals to build a more reliable and individualized treatment plan.