Ordinarily, the prostate (a walnut-sized gland surrounding the urethra) secretes seminal fluid to boost ejaculate volume. It also secretes prostate specific antigen (PSA), an enzyme which reduces semen viscosity.

Women secrete PSA via the paraurethral or Skene’s glands to help lubricate the vagina during intercourse.^2,18,19,20

All men normally have some PSA in their blood, but levels can increase due to:^21,22,23

·     - recent vigorous exercise;

·     - urinary tract infections;

·     - prostate stimulation (eg recent ejaculation, anal sex);

·     - enlarged prostate (benign prostatic hyperplasia/BPH);

·     - prostatitis;

·     - prostate cancer;

·     - age.

Larger prostates, whether cancerous or not, tend to produce more PSA. The prostate density (PSA level ÷ prostate size – ng/ml/ml) is used to help with decisions about further testing or care options.²³

While there is no direct correlation between PSA level and PC, extremely high PSA levels are almost always cancer related.²²

Note that 5-alpha-reductase inhibitors (finasteride, dutasteride) used for BPH can reduce PSA levels.²⁴