Watch for antipsychotic-induced rise in prolactin.(Clinical Rounds)

NEW YORK -- Antipsychotics can induce elevated levels of prolactin that may require dosage changes or medication switches, Dr. Harold E. Carlson said at a psychopharmacology update sponsored by the American Academy of Child and Adolescent Psychiatry.

Psychiatrists may refer patients who are taking antipsychotics because their patients are experiencing missed menses, nipple discharge, sexual dysfunction, or delays in pubertal development, all of which are signs and symptoms of hyper-prolactinemia, said Dr. Carlson, chief of the division of endocrinology at the State University of New York at Stony Brook.

Prolactin suppresses the release of gonadotropin-releasing hormone from the hypothalamus, which leads to hypogonadism by lowering serum levels of luteinizing hormone and follicle-stimulating hormone. Prolactin also is known to stimulate lactation. Dopamine inhibits the release of prolactin by binding to D2 dopamine receptors in the pituitary gland. Most antipsychotics, especially atypical antipsychotics, have D2-dopamine antagonist activity. They raise serum prolactin levels by varying degrees because they vary in their antagonist activity on, and affinity for, the D2 dopamine receptors.

In general, serum prolactin levels are raised the most by risperidone (Risperdal), followed by haloperidol (Haldol), olanzapine (Zyprexa), ziprasidone (Geodon), quetiapine (Seroquel), clozapine (Clozaril), and aripiprazole (Abilify). Quetiapine and clozapine are "pretty neutral" in their effect on serum prolactin levels, while aripiprazole is actually a partial D2-receptor agonist and suppresses serum prolactin to below baseline levels, Dr. Carlson said.

Patients with elevated serum prolactin levels should receive a pregnancy test (when appropriate) and tests of serum levels of thyroid-stimulating hormone (in case of hypothyroidism) and creatinine (in case of renal insufficiency) to rule out these three "very common" causes of hyperprolactinemia, he said.

Once an antipsychotic is established as the cause of elevated prolactin, one could try reducing the dose of the drug or switching to a more prolactin-sparing antipsychotic--if medically feasible--when the level of serum prolactin is ...