Prolactin

A prolactin test measures the level of the hormone prolactin, which is secreted by the pituitary gland, in your blood. Prolactin also has many other functions, including an essential role in maintenance of the immune system. Increased levels of prolactin are even natural for pregnant women, as prolactin helps to produce breast milk.

Elevated levels of prolactin can interfere with ovulation in women, decrease libido in men, and decrease fertility. A damaged pituitary gland may not be able to make normal amounts of prolactin so low levels can also indicate a health problem that should be addressed.