PSA Test

PSA (prostate-specific antigen) is an enzyme secreted by the prostate itself that gives semen its consistency. This enzyme is present in very high concentrations within prostate tissue.

It is normally found in the prostatic ducts and in semen in much greater amounts than in the blood. However, in some situations where the cellular integrity of the prostate is damaged, its passage into the blood increases and its blood level rises. The reason the PSA level in the blood rises in prostate cancer is that tumour tissue sometimes disrupts the cellular integrity of the prostate.

PSA helps with early detection but does not establish a diagnosis; if the elevation persists, a urologist examination, prostate MRI and, if necessary, a biopsy are performed. Since this test came into use, a decline in prostate cancer-related death rates has begun to be seen. However, the fact that it can also rise for reasons other than cancer reduces the specificity and sensitivity of this test.

PSA values show a natural increase of on average 0.05 ng/ml every year.

Reference for normal PSA values: Hans-Joachim Luboldt, Joachim F. Schindler, Herbert Rubben .Age-Specific Reference Ranges for Prostate-Specific Antigen as a Marker for Prostate Cancer.eau-ebu update series 5 (2007) 38–48.

1. 0 - 2.5 ng/ml for ages 40-49
2. 0 – 3.5 ng/ml for ages 50-59
3. 0 – 4.5 ng/ml for ages 60 – 69
4. 0 – 6.5 ng/ml for ages 70 and over

Normal values are accepted as stated above.

PSA may also vary according to race and prostate volume. Black men have higher values than white men in the same age group. Apart from cancer, it may be elevated in BPH, prostatitis, after sexual intercourse, after a biopsy, after a rectal examination, in urinary tract infection, and after urinary tract interventions (catheterisation) and surgery. Finasteride and dutasteride lower PSA by about half; if you are taking them, inform your doctor and the laboratory before the test.

A sudden PSA rise in a man whose PSA value has been normal is usually due to non-cancer causes. In such cases, one can wait for the cause of the elevation to be resolved and for some time to pass. The time varies depending on the cause; a high PSA should be repeated after a few weeks (6-8 weeks after an infection or procedure) in the same laboratory.

In conclusion, not every PSA elevation means cancer, and a low value is not sufficient to rule out cancer. It should be remembered that prostate cancer is detected in 1 out of every 5 patients whose values are within normal limits.

For this reason, in the diagnosis of prostate cancer, a digital rectal examination of the prostate is considered together with the PSA value. Some additional tests may be performed for the diagnosis of prostate cancer in patients in whom cancer is suspected.