The effect of routine digital examination of the prostate on serum acid phosphatase

Serum level of prostatic acid phosphatase after diagnostic rectal examination. Comparison between spectrophotometric and a radioimmunological assay

The serum level of prostatic acid phosphatase was measured before and after diagnostic rectal palpation in 24 patients with a clinically normal prostate and in 32 patients with benign hyperplasia of the prostate. There was a significant rise in the 32 patients with benign prostatic hyperplasia. All of the values had returned to the original level after 24 h. Similar results were obtained with either a spectrophotometric method or a radioimmunoassay.

The effect of rectal examination on serum acid phosphatase levels in benign and malignant prostatic disease

Serum acid phosphatase was measured in patients with enlarged benign and malignant prostate before and after rectal examination. Amongst the patients with benign glands, rectal examination did not produce any significant false elevation of the enzyme. Rectal examination, however, caused a rise in the enzyme level in a few untreated cancer patients and in cancer patients who had become refractory to hormonal therapy. This rise would help rather than mislead in the diagnosis of malignant prostate and also in identifying treated patients who had become refractory to treatment. Thus, when serum acid phosphatase is properly determined, elevated levels should always arouse suspicion of malignant prostate or other lesions associated with high enzyme level even if such determination was preceded by rectal examination.

There appears to be no merit in the teaching that the determination of serum acid phosphatase should be delayed after rectal examination.