To the Editor.—
Elevated heart enzyme levels in apparent absence of myocardial infarction was recently discussed by P. F. Chestnut and J. S. LaDue (227:808, 1974). We want to draw attention to the possibility of an inherited enzyme increase.Determination of serum diamine oxidase (DAO) (EC 184.108.40.206) activity is used as an index of fetoplacental integrity and trophoblastic tumor activity.1 The serum DAO in a normal population is 4±2 (mean±SD) milliunits/liter for adult men and nonpregnant women.2 During pregnancy, it is increased about 500 times. Serum DAO is reported to be increased in medullary carcinoma of the thyroid and after heparin administration. The serum enzyme activity in seemingly healthy, nonpregnant individuals might also deviate sharply from the normal.
Report of a Case.—
A 30-year-old, formerly healthy woman was delivered of a hydatidiform male in the fourth month of pregnancy. Repeated determination of serum DAO showed abnormally high values