Which test is commonly used to evaluate lung function, including lung capacity and air flow?

• A. Sigmoidoscopy
• B. Pulmonary Function Tests (PFTs)
• C. Sodium Levels
• D. Thoracentesis

Answer: (B)

Pulmonary Function Tests are the standard way to assess how well the lungs work, including both how much air they can hold (lung volumes and capacities) and how quickly air moves through them (airflow). The most common component is spirometry, which measures flow and volume, giving values like FEV1 and FVC and their ratio to identify obstructive vs restrictive patterns. Additional parts of PFTs measure total lung capacity and residual volume to quantify capacity, and diffusion capacity (DLCO) to gauge how well gases like oxygen pass from the air into the blood. Together, these tests provide a comprehensive picture of lung function and help diagnose and monitor conditions such as asthma, COPD, and interstitial lung disease.

Other options are not focused on lung function: a sigmoidoscopy examines the colon, a thoracentesis is a procedure to remove pleural fluid, and sodium levels are a general blood test not specific to lung performance.