**8. Hemodilution**

Undoubtedly, a negative feature of PSA concentration is the fact that it is subject to hemodilution. Some authors claim that in overweight and obese patients PSA concentration is lower, which is, in the first place, caused by the aforementioned phenomenon. This phenomenon is supposed to consist in the dissolution of PSA mass in a large amount of plasma, finally resulting in lower PSA concentration. PSA is a protease which physiological function consists in liquefying semen.

Every man is characterized by a quite invariable amount (mass) of this secreted into the blood protein, depending on age, the size of prostate, the presence of cancer or other prostate diseases. However, standard PSA determination means that PSA mass is dissolved in plasma volume which is mainly dependant on the obesity extent. This led some authors to explore new markers independent of hemodilution (Bryniarski et al., 2011). PSA mass meets these criteria, but further studies are needed to demonstrate its superiority over standard PSA concentration.
