Elevated levels of angiotensin-converting enzyme in Pneumocystis carinii pneumonia. 
Serum angiotensin-converting enzyme (ACE) levels are elevated in sarcoidosis and have been used both to diagnose and to assess response to treatment of this disease.  We report significantly (p less than .0005) elevated ACE levels in patients with Pneumocystis carinii pneumonia (PCP) (49 +/- 14 U/L) compared with normal control subjects (32 +/- 11 U/L) tested within 48 hours of hospital admission.  Serum ACE levels in smoking control subjects (33 +/- 11 U/L) were not significantly (alpha = .05) different from nonsmoking control subjects (32 +/- 11 U/L), but the levels in PCP patients who smoked (55 +/- 15 U/L) were significantly (p less than .025) higher than in those who did not smoke (42 +/- 10 U/L).  In addition to suggesting a possible clinical use for measuring ACE levels in suspected or confirmed PCP, we speculate that elevations in serum ACE levels may reflect macrophage dysfunction in patients with PCP.