What is the role of pulmonary function tests in the workup of scleroderma?

Updated: Jun 24, 2020
  • Author: Sergio A Jimenez, MD, MACR, FACP, FRCP(UK Hon); Chief Editor: Herbert S Diamond, MD  more...
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Pulmonary function testing is important in all patients with systemic sclerosis, [125, 126, 127, 128] although lung volumes may correlate poorly with the extent of interstitial lung disease. Pulmonary function tests should be performed every 6 to 12 months to detect early abnormalities indicative of development and/or progression of pulmonary hypertension or pulmonary fibrosis. Results of pulmonary function testing are ultimately abnormal in 80% of the patients.

Carbon monoxide diffusion capacity (DLCO) is very sensitive and helps establish lung involvement at an earlier stage. Pulmonary function tests may demonstrate a restrictive pattern with decreased forced vital capacity and total lung capacity and a low DLCO. These changes reflect fibrotic infiltration in the lung (see images below). An isolated or disproportionate reduction of DLCO with a ratio of forced vital capacity (FVC) or total lung capacity (TLC) to DLCO of greater than 1.6 indicates pulmonary vascular obliteration associated with pulmonary hypertension.

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