Pulmonary Function in Pulmonary Sarcoidosis

The pulmonary function test (PFT) has been widely used in sarcoidosis. It may vary due to the severity, extent, and the presence of complications of the disease. Although the PFT of most sarcoidosis patients is normal, there are still 10-30% of cases who may experience a decrease in the PFT, with a progressive involvement of lungs. Restrictive ventilatory impairment due to parenchymal involvement has been commonly reported, and an obstructive pattern can also be present related to airway involvement. The PFT may influence treatment decisions. A diffusing capacity for carbon monoxide (DLCO) < 60% as well as a forced vital capacity (FVC) < 70% portends clinically significant pulmonary sarcoidosis pathology and warrants treatment. During follow-up, a 5% decline in FVC from baseline or a 10% decline in DLCO has been considered significant and reflects the disease progression. FVC has been recommended as the favored objective endpoint for monitoring the response to therapy, and an improvement in predicted FVC percentage of more than 5% is considered effective.