The Estimation of Prostatic Phosphatase in Serum and Its Use in the Diagnosis of Prostatic Carcinoma

Abstract

The diagnostic use of serum acid phosphatase detns. was studied in 87 cases of prostatic carcinoma, 95 of benign hypertrophy, and 153 other diseases. The total acid phosphatase titre is raised in most cases of prostatic carcinoma with bone metastases and in a small proportion without demonstrable metastases. The raised titres vary from 5-281 units on the scale of Gutman and Gutman (1938). In a few cases of non-prostatic diseases, minor rises are encountered. In differential diagnosis, it is sometimes important to distinguish acid phosphatase of prostatic origin and that from other sources. To assist diagnosis when the phosphatase level is only slightly raised, methods of inactivation of prostatic phosphatase were studied. Prostatic phosphatase in serum is inactivated either by incubation of 1 hr. at 37 [degree]C or by treating with 2/5 vol. of ethyl alc. 1/2 hr. at room temp. The alc. inactivation method is more specific for prostatic phosphatase and has been adopted as a routine procedure. Incubation of serum at 37[degree]C is not recommended as a routine diagnostic test. Prostatic phosphatase is regularly inactivated. In most sera from non-prostatic diseases, the acid phosphatase is not inactivated, but exceptions are frequent enough to make the test unreliable. Inactivation by alc. at room temp. gives a specific test for prostatic phosphatase and an approx. quantitative measure of the prostatic fraction of the acid phosphatase. It clearly distinguishes the raised titres due to prostatic phosphatase and those of different origin. It may sometimes make it possible to detect prostatic phosphatase even when the total titre of the serum is not raised. The present work confirms both the value and limitations of total serum acid phosphatase as a diagnostic test.