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.
By age 60, the limit is up to 4.5; by age 70, a PSA of 6.5 could be considered normal. Even so, a study done in Sweden and reported in the medical journal BMJ found that a low PSA at age 60 is especially welcome news.