What is the role of pulmonary testing in the workup of granulomatosis with polyangiitis (GPA)?

Updated: Aug 31, 2021
  • Author: Christopher L Tracy, MD; Chief Editor: Herbert S Diamond, MD  more...
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In patients old enough to cooperate, spirometry, plethysmography, and diffusing capacity should be performed as soon as possible to identify abnormalities and provide a baseline.

Good inspiratory and expiratory loops should be obtained. If these are flattened, subglottic stenosis or other causes for central airway obstruction should be suspected.

Because most pediatric subglottic stenosis is not found initially, spirometry, particularly with a good baseline flow volume loop, can be used to screen noninvasively for this development.

Spirometry may show either restrictive or obstructive patterns, and the diffusing capacity of lung for carbon monoxide (DLCO) may be decreased or increased, as in the case of DAH. [3]

Although a decreased diffusing capacity is a common finding in GPA, it may still fall within the reference range. In alveolar hemorrhage, the single-breath diffusing capacity is increased.

In adults, limitation to flow and decrease of the ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) are the most common pulmonary function test abnormalities. Focal and interstitial infiltrates and peripheral mass lesions produce decreased lung volumes.

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