Normal values for lung function in spirometry are influenced by which of the following factors?

Lung function values measured by spirometry are influenced by several physiological and demographic factors, which include patient age, gender, and height.

Age affects lung function as respiratory mechanics and capacities can change over time. Generally, lung volumes increase to a peak in early adulthood and tend to gradually decrease with aging due to loss of elasticity and the effects of age-related diseases.

Gender also plays a significant role in determining lung volumes and capacities. Typically, males have larger lung volumes compared to females, which is attributed to differences in body size, thoracic cavity dimensions, and overall lung structure.

Height is another critical determinant because lung volumes tend to increase with greater height. Taller individuals usually have larger thoracic cavities, which can accommodate larger lungs, resulting in higher expected values for lung function tests.

Considering these factors collectively, it is clear that normal spirometric values are established based on average population data that take into account age, gender, and height. When evaluating lung function, it is essential to use these parameters to interpret the results accurately in the context of individual patients. Thus, all of the specified factors contribute to the normal values for lung function in spirometry.