Hyperprolactinaemia

What it is

Hyperprolactinemia is a high prolactin level. Dopamine normally inhibits prolactin secretion in the pituitary gland, so a tumor that makes prolactin, and a drug that blocks that dopamine, end in the same place. The hormonal changes run together: prolactin up, LH and FSH down, and with them testosterone and estrogen, and each of these hormonal changes has its own features in the female and in the male. That is why the clinical features are as much features of low testosterone and low estrogen as they are of prolactin itself.

Causes and risk

• Prolactinoma, the pituitary tumor. A prolactin level > 200 ng/mL is virtually diagnostic of it.
• Drugs. Risperidone can increase prolactin levels and is one of the antipsychotics most commonly associated with hyperprolactinemia, because it is a dopamine D2 receptor antagonist: it blocks dopamine, the inhibition on prolactin is reduced, and prolactin levels increase.
• Pregnancy.
• Hypothyroidism, which leads to high prolactin through TRH.
• Renal insufficiency.

The antipsychotics are named as a group and not only by one drug: many antipsychotic medications, through hypothalamic dopamine blockade, are associated with an increased risk for hyperprolactinemia. It can be asymptomatic, but it can also lead to gynecomastia and to infertility, sexual dysfunction, and in women irregular menses. A 24 year old man with schizophrenia stabilized on an antipsychotic who presents with gynecomastia has hyperprolactinemia as the most likely cause, rather than persistent pubertal gynecomastia, an increased estrogen level, an elevated cortisol level or a pituitary adenoma.