Diurnal variation of prostatic acid phosphatase (PAP) in urologic patients with nonprostatic disease.

Variation in serum prostatic acid phosphatase (PAP) level over a twenty-four-hour period was studied in 18 urologic patients with no prostatic disease. Hourly, twenty-four-hour serum PAP level was determined using Elisa method. Seven of 18 patients (38.8%) showed appreciable change with definite diurnal pattern. PAP level was highest in early AM hours and lowest in the PM period. The difference between the mean AM and PM periods was statistically significant (P less than 0.01). Four of 18 patients showed no change over the twenty-four hours while 7 patients showed some variation without definite diurnal pattern. Such changes may lead to variation in serum PAP level and may lead to false positive results.