The value of serial serum angiotensin converting enzyme determinations in hospitalized patients with lung disease

Abnormal serum angiotensin converting enzyme (ACE) activity has been reported in various human lung disorders and in laboratory animals with acute lung injuries. To test the value of serum ACE activity as an indicator of lung damage and its assistance in diagnosis or prognosis, 328 serum samples were obtained from 108 hospitalized patients with lung disease and 26 normal subjects. When patients were clinically grouped by disease entity, only the sarcoidosis group showed elevated mean serum ACE. Significantly increased serum ACE was found in 17 patients with various lung diseases (15% of hospitalized patients) 12 of whom also had concomitant liver disease. It is hypothesized that the liver may play a role in the normal metabolism of ACE being released by lung endothelial injury. Significantly low levels were seen in many acute and chronic lung injuries; specifically the groups with chronic obstructive lung disease, lung cancer, acute pneumonia, aspiration pneumonitis, gram-negative sepsis, acute myocardial infarction, and congestive heart failure. Serial measures of ACE in 71 patients with lung injuries showed that significantly decreasing levels over successive days were associated with a very high mortality. A single ACE measurement did not predict the presence or extent of lung injury, or aid in diagnosis or prognosis, but serial levels are of value prognostically.