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.
Recent data has redefined the way that urologists look at PSA, and what is considered a normal PSA. Age-adjusted PSA values take into account that a 40-year-old should not have the same PSA as an 80-year-old. Accepted age-adjusted PSA rates are below 2.4 ng/ml for men under the age of 50 and 6.5 ng/ml for patients in their 70s. Other limits have been defined for varying age ranges, but there is not universal agreement about the accuracy of the age-adjusted levels.