What else should be investigated in a patient with persistent cough and decreased exercise tolerance?

In the context of a patient exhibiting a persistent cough and decreased exercise tolerance, pulmonary function tests are a critical next step due to their ability to assess lung capacity and the effectiveness of airflow. These tests can help identify any underlying respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), or restrictive lung disease.

Given that the symptoms presented—cough and decreased exercise tolerance—are often related to pulmonary issues, obtaining a comprehensive evaluation of lung function is essential. This allows for differentiating between obstructive and restrictive patterns and can reveal the presence of conditions that may require targeted treatments, such as bronchodilators or other respiratory therapies.

While other investigations, such as allergy testing or cardiac workups, may eventually be warranted based on findings or if any additional symptoms arise, pulmonary function tests offer direct insights into the respiratory system's status and can guide immediate management and further diagnostic pathways.