Tc-99m DTPA aerosol lung clearance test in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) can affect every organ. Involvement of the lung in systemic lupus erythematosus may be a significant cause of morbidity and mortality. To evaluate alveolar epithelial damage in SLE, we studied lung epithelial permeability by measuring the clearance of inhaled Tc-99m DTPA aerosol. Twenty-three SLE patients without clinical pulmonary manifestations were studied. Of the 23 patients, 16 had normal clearance rates of Tc-99m DTPA (T1/2 > 60mins) and normal chest X-ray findings. A mild increase in the clearance rate was found in 5 cases (T1/2 between 40-60 min) and a significant increase in clearance rate in the remaining 2 (T1/2 < 40mins). Totally, 30% (7/23) of SLE patients have abnormal lung permeability. Of the 7 patients with abnormal clearance of Tc-99m DTPA, 3 had abnormal findings in chest X-rays and four had normal chest X-rays. Our study suggests that the clearance of Tc-99m DTPA aerosol may be a useful complementary study to assess pulmonary involvement in SLE.