PSA Total
Sample: Serum 0.5 mL
Status: Accredited
Schedule: Daily
Units: ng/mL
Range: (See table)
Remarks: PSA (Prostatic Specific Antigen) is an antigen which as been identified to be specific for the prostatic tissue and is not present in any other normal tissues. It is a protease that participates in the lysis of seminal coagulum. More than 90% of prostatic cancer patients show high levels of serum PSA, therefor PSA is a powerful serum marker for the cancer of prostate. PSA is quite useful follow-up marker, since it serves as an excellent indicator for assessing the response to the anti-cancer therapy. Nevertheless, rather than specific diagnostic tool for prostate cancer diagnosis, PSA indicates the presence of active prostatic disease, being necessary other special procedures the determine whether the disease is a malignancy. Low levels of serum PSA that remain below 10 ng/mL for appreciated period of time after treatment indicate a good prognosis, whereas high PSA levels that remain after anti-cancer treatment, are associated with progression of the disease. On the other hand, remarkable high PSA levels are invariable associated with a metastatic process. Patients with serum PSA levels which lie between 4.0 - 10 ng/mL must be further investigated with digital rectal examination and fPSA/PSA evaluation (see freePSA). Some autors claim that complex PSA (cPSA) is better discriminator than fPSA/PSA ratio. cPSA is a group of at least three different molecules of PSA (different from fPSA). Nevertheless, latest studies indicate that, at least up to date, it is unclear if cPSA offers better discrimination for more accurate diagnosis of prostate disseases. At present, cPSA is only a little better than total PSA (tPSA) when used as first screening test for postate disease. It has been demostrated that 3rd generation PSA (3G PSA) test is equivalent to cPSA as a discriminator factor, thanks its high sensitivity and specificity (near 0.002 ng/mL).
