One year follow-up of lung clearance of 99mTc-diethylene triamine penta-acetic acid and disease activity in sarcoidosis

Background and aim of the work: In interstitial lung disease lung clearance of Tc-99m-diethylenetriaminepentaacetic acid (DTPA) reflects alterations in the alveolar capillary barrier. Our objective was to describe changes in lung clearance during one year in sarcoidosis, and to relate clearance to other data of lung function and disease activity. Methods: Twenty-three newly diagnosed patients were studied with respect to lung DTPA clearance, spirometry, Ga-67 scintigraphy and serum angiotensin converting enzyme (SACE). Lung mechanics and arterial PO2 at rest and exercise were studied in patients with radiological parenchymal changes. Six of these patients were prescribed peroral steroids. Results: At inclusion lung DTPA clearance measured over 30 minutes was 53 +/- 16 minutes and at follow-up 59 +/- 20 minutes (p > 0.05). The number of pathological clearance curves at inclusion was 10 and at follow-up 6. In treated patients lung DTPA clearance improved as did lung Ga-67 score and SAGE. However, lung clearance did not correlate significantly with changes in lung function or other activity parameters. Conclusions: Lung DTPA clearance reflects lung function from an aspect different from that of other methods, It seems sensitive to pathology reversed by steroids and may, in some cases, help in the evaluation of disease activity.