Serum zinc and angiotensin-converting enzyme levels in patients with lung cancer.

Forty-two patients with lung cancer and 72 healthy subjects were studied in order to determine a possible relationship between serum zinc and angiotensin-converting enzyme (ACE), a peptidyl dipeptide hydrolase. Serum zinc levels were 105 +/- 21 micrograms/dl in control subjects and 50 +/- 19 micrograms/dl in patients, and angiotensin-converting enzyme activity was 296 +/- 28 U/l in the former and 240 +/- 55 U/l in the latter using hippurylglycylglycine as a substrate. The findings obtained show that the decreased levels of angiotensin-converting enzyme may be related to decreased serum zinc levels and that the primary defect may be the zinc deficiency in these patients.