Circadian and day-to-day variation of prostatic acid phosphatase

The circadian and day-to-day variation of serum levels of prostatic acid phosphatase determined by radioimmunoassay was investigated in 10 men with a normal prostate, 8 with benign prostatic hyperplasia and 10 with prostate cancer. Serum samples were obtained on 1 day at 8 a.m., 12:00 noon and 4:30 pm. in 23 patients, and on 3 consecutive days at 8 a.m. in an additional 5 patients. There was a variability in enzyme level throughout the day but without any distinct pattern. Prostate cancer patients with elevated levels of prostatic acid phosphatase did demonstrate a greater variability throughout the day than patients with a normal prostate or with benign prostatic hyperplasia. The day-to-day serum prostatic acid phosphatase in patients with a normal prostate varied little and remained within the normal range.