At a Glance

Hyperprolactinemia is the most common endocrine disorder of the hypothalamic-pituitary unit. In premenopausal women, hyperprolactinemia causes hypogonadism, leading to symptoms of infertility, oligomenorrhea or amenorrhea, and galactorrhea. Hyperprolactinemia is often clinically silent in postmenopausal women who, by definition, are already hypogonadal. In men, hyperprolactinemia causes hypogonadism manifested by decreased libido, impotence, infertility, and, rarely, galactorrhea.

Several drugs are known to cause minimal to moderate hyperprolactinemia:

Anticonvulsants

Phenytoin

Antidepressants

Tricyclic antidepressants

Selective serotonin reuptake inhibitors

Antihypertensives

Labetolol

Verapamil

Catecholamine-depleting agents

Reserpine

Dopaminergic-blocking agents

Pheothiazines

Butyrophenones

Benzamides

Dopamine-depleting agents

α-methyldopa

Estrogens

H2-receptor blocking agents

Cimetidine

Ranitidine

Neuroleptics

Chlorpromazine

Promazine

Trifluoperazine

Fluphenazine

Butaperazine

Perphenazine

Thiethylperazine

Thioridazine

Haloperidol

Pimozide

Thiothixene

Molindone

Neuropeptides

Thyroid-releasing hormone

Opiates and Opiate Antagonists

Heroin

Methadone

Apomorphine

Morphine

Oral contraceptives

These should be ruled-out as potential causes of hyperprolactinemia prior to investigating organic causes.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

Measurement of serum prolactin is necessary to identify hyperprolactinemia. Testing can be performed without regard to time of day, because routine daily activities have little influence on prolactin concentration.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications – OTC drugs or Herbals – that might affect the lab results?

Prolactin concentrations slightly greater than the reference interval should be confirmed by repeat testing on a new blood sample, because prolactin may be influenced by strenuous exercise, emotional or physical stress, or rigorous stimulation of breast tissue.

Macroprolactin is a complex of prolactin and IgG and is a source of hyperprolactinemia in some individuals. Because of its high molecular mass, macroprolactin has prolonged clearance that can cause an apparent hyperprolactinemia. In the absence of clinical symptoms, hyperprolactinemia due to macroprolactin can cause clinical confusion. It is important to be aware that macroprolactinemia can coexist with true hyperprolactinemia.