Frolic is a playful word with a happy history. It traces back to the Dutch word vroolijk (merry), which in turn evolved from a Middle Dutch combination of vro (happy) and the adjectival suffix -lijc (-ly).
A normal PSA level is considered to be 4.0 ng/mL (nanograms per milliliter of blood). 1  For men in their 50s or younger, a PSA level should be below 2.5 in most cases.  Older men often have slightly higher PSA levels than younger men.
Prostate-specific antigen, or PSA, is a protein produced by normal, as well as malignant, cells of the prostate gland. The PSA test measures the level of PSA in a manâs blood. For this test, a blood sample is sent to a laboratory for analysis. The results are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.