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.
1 Men over the age of 70 years have normal PSA levels that are less than 6.5 ng/mL. 2  It is also important to note that the normal ranges of PSA results may vary from one laboratory to another. 3  The abbreviation ng/mL stands for nanograms per milliliter. Men over the age of 70 years have normal PSA levels that are less than 6.5 ng/mL. 2  It is also important to note that the normal ranges of PSA results may vary from one laboratory to another. 3  The abbreviation ng/mL stands for nanograms per milliliter.