Lung volume measurement is a medical test that assesses the amount of air the lungs can hold. This measurement helps doctors evaluate lung function and diagnose respiratory conditions. Common methods include spirometry, which measures the volume of air inhaled and exhaled, and plethysmography, which determines lung volume by measuring changes in pressure within a sealed chamber. These tests are important for understanding conditions like asthma, chronic obstructive pulmonary disease (COPD), and other lung diseases. By knowing lung volumes, healthcare providers can tailor treatment plans and monitor the effectiveness of therapies over time.