Prostate Specific Antigen (PSA) is a naturally occurring protein, which is produced by the prostate gland and secreted in the ejaculate. The function of PSA is to liquefy semen once it has been deposited in the vagina so that the sperms can swim toward the egg.
Normally only low levels of PSA enter the blood stream. However, if the prostate gland is diseased, disrupting the normal structure of the tissue, large amounts of PSA can leak into the circulation and cause raised PSA levels in the blood.
Causes of elevated PSA
- Prostate cancer. The higher the PSA the higher the risk of prostate cancer.
|PSA level (µg/L)||Risk of prostate cancer|
|4.0 to 10||25%|
|10 to 20||50%|
|More than 20||75%|
- PSA can also be elevated from non-cancerous causes e.g.
- Benign prostatic hyperplasia (BPH), which commonly occurs as men get older.
- Urinary tract infection or prostatitis.
- After intercourse – PSA can be slightly elevated in some men for 2-3 days after sex.
- Strenuous physical activity such as bike riding may elevate PSA for a few days.
- Insertion of a catheter or cystoscopy procedure can cause a transient PSA elevation.
It is important to note that prostate cancer can occur even if the PSA is in the normal range. Approximately 20% of prostate cancers are diagnosed in men with a normal PSA level, usually after they are discovered to have a prostatic nodule on digital examination.
If you have been found to have an elevated PSA your GP will take a history and perform a digital rectal examination to feel you prostate gland. Additional tests should be conducted such as a urine test to exclude a urinary tract infection and a repeat PSA test to confirm the level is elevated.
Referral to a urologist for further investigation is indicated if you have a persistently elevated PSA level and/or an abnormal feeling prostate on digital examination. The urologist may recommend further investigation with a MRI scan and / or prostate biopsy.
For more information on PSA testing please download a PDF from the Andrology Australia website