Test Catalog


Macroprolactin—Big-Big Molecules Create Big Problems in Diagnosis of Hyperprolactinemia

March 2007

Hyperprolactinemia is the presence of abnormally-high levels of prolactin in the blood. Prolactin is a hormone produced by the anterior pituitary gland that stimulates milk production. Women with hyperprolactinemia usually present with irregular menstrual periods, often accompanied by galactorrhea. Other symptoms include infertility and decreased libido. Men typically present with impotence, infertility and other signs of hypogonadism. Hyperprolactinemia is often caused by the presence of a pituitary tumor. However, the presence of a high-molecular mass complex of prolactin called macroprolactin can cause false-high test results, leading to a misdiagnosis of hyperprolactinemia. This misdiagnosis can generate inappropriate follow-up testing as clinicians search for the cause of the hyperprolactinemia, performing unnecessary CT or MRI imaging, and, potentially, pharmacologic or surgical treatment.

Macroprolactin is a high-molecular–weight complex of prolactin and immunoglobulin found in a small proportion of people. Macroprolactinemia, frequently referred to as pseudo-hyperprolactinemia, is an apparently benign clinical condition; it does not appear to affect milk production or gonadal activities. Macroprolactin is a complication to the accurate evaluation of prolactin concentrations. To accurately assess the patient for hyperprolactinemia, it is necessary to evaluate both prolactin and macroprolactin levels.

Mayo Medical Laboratories offers test #87843 Macroprolactin, Serum, reports both prolactin and macroprolactin results which determines whether the apparent elevation in serum prolactin concentration is due to true hyperprolactinemia or to macroprolactinemia.

View the full article

Tell Us What You Think