Abnormal results of pulmonary function studies

This code signifies objective findings from tests designed to assess lung function that deviate from established normal ranges. These abnormalities indicate impaired respiratory mechanics or gas exchange, but do not specify the underlying cause. It serves as a preliminary diagnosis when further investigation is required to determine the etiology of the pulmonary dysfunction.

Use this code when a patient's pulmonary function test (PFT) results, such as spirometry, lung volumes, or diffusion capacity, are reported as abnormal by the interpreting physician. Documentation must clearly state that PFTs were performed and that the results were outside normal limits, often accompanied by specific abnormal values or interpretations (e.g., "restrictive pattern," "obstructive pattern," "reduced DLCO"). This code is appropriate when a definitive diagnosis for the PFT abnormality has not yet been established.

• Do not use this code if a definitive diagnosis explaining the abnormal PFTs (e.g., asthma, COPD, pulmonary fibrosis) is already known and documented.
• This code is often used as a primary diagnosis when the abnormal PFTs are the reason for the encounter, or as a secondary diagnosis when evaluating other conditions.
• Always review the full medical record to ensure the most specific diagnosis is captured; this code is for unspecified abnormal results.