The concentration of immunoreactive prostate specific antigen is not decreased in viscous semen samples.

The concentration of immunoreactive prostate specific antigen (PSA) was determined in the seminal plasma of 79 men who were classified into 4 groups according to sperm characteristics: there were 3 groups with low viscosity sperm (normal, large or small volume) and one group with high viscosity and normal volume. PSA concentrations in the group with high viscosity were not significantly different from the group with low viscosity and normal or large volume. PSA was significantly increased only in the "small volume group" (p less than 0.01). These results show that absolute amounts of PSA are not decreased in seminal plasma with high viscosity and therefore are not the cause of abnormal liquefaction of the semen in these patients.