Hyperprolactinemia

9.5 Hyperprolactinemia

Description Dopamine inhibits the activity of prolactin-making cells in the pituitary gland. Because they are dopamine receptor antagonists, most antipsychotic medications can block this baseline prolactin inhibition and thus cause hyperprolactinemia. Prolactin levels vary with age, gender, stress level and physical activity. Hyperprolactinemia can be defined as prolactin levels greater than 28.3 ng/ml for women and 16.5 ng/ml for men (Soto-Pedre et al., 2017).

Hyperprolactinemia can negatively impact health and life quality by contributing to: • Breast enlargement • Galactorrhea • Gynecomastia • Hirsutism • Sexual dysfunction • Erectile dysfunction • Irregular periods or amenorrhea • Infertility • Erectile dysfunction • Reduced testosterone levels • Reduced bone mineral density • Weight gain • Autoimmune thyroiditis

Risk factors and prevention strategies The risk for hyperprolactinemia is related to the intensity of dopamine receptor antagonism. The extent of dopamine receptor antagonism is related to the affinity of the medication (higher-affinity drugs pose greater risk) and the dose of medication employed. (Even lower-affinity drugs can cause hyperprolactinemia at sufficiently high doses.) Because of its partial agonist activity, aripiprazole does not elevate prolactin levels.

Treatment There are several options for treating antipsychotic-induced hyperprolactinemia. • Adding low doses of aripiprazole (2 to 5 mg/day) often reduces elevated prolactin levels. • The dose of the offending medication can be reduced. • The offending medication can be switched to one with lower dopamine receptor affinity. • Adding metformin has been reported to reduce elevated prolactin levels in antipsychoticinduced hyperprolactinemia (Zheng et al., 2017). • Adding topiramate has been reported to reduce elevated prolactin levels in antipsychoticinduced hyperprolactinemia (Huang et al., 2017).