DOES SERUM ANGIOTENSIN CONVERTING ENZYME REFLECT INTENSITY OF ALVEOLITIS IN SARCOIDOSIS

Serum angiotensin converting enzyme activity is increased in many patients with pulmonary sarcoidosis and has been proposed as a measure of disease activity. Assay of serum angiotensin converting enzyme, bronchoalveolar lavage and Ga scans were performed in 27 patients with biopsy proved pulmonary sarcoidosis. There was a positive correlation between serum angiotensin converting enzyme activity and an index of pulmonary Ga uptake assessed by the National Institutes of Health Method (r = 0.7, P < 0.001). There was no significant relationship (r = 0.19) between serum angiotensin converting enzyme activity and bronchoalveolar lavage lymphocytes expressed as a proportion of cells recovered. Increase in the enzyme activity had a sensitivity of 50% as a means of detecting high intensity alveolitis but specificity was only 45%. There was no significant difference in mean angiotensin converting enzyme activity between the following groups: those with positive and those with negative Ga scans; those with bronchoalveolar lavage lymphocyte counts .ltoreq. 28% and those with counts > 28%. Although there was a significant correlation between the enzyme activity and 1 component of the alveolitis of sarcoidosis, the data suggest that serum angiotensin converting enzyme activity alone is neither sensitive nor specific enough for high intensity alveolitis.