Hyperprolactinemia
Hyperprolactinemia is an elevated prolactin level, evaluated per the Endocrine Society Clinical Practice Guideline (2011).
Symptoms
Irregular periods, unexpected milk production (galactorrhea), infertility, and reduced libido in women; low libido and erectile dysfunction in men -- symptoms reflect prolactin's suppression of reproductive hormones.
Causes and risk
A prolactin-producing pituitary tumor (prolactinoma) is the most common pathologic cause; medications (many antipsychotics, some antidepressants), pregnancy, and hypothyroidism are common non-tumor causes worth ruling out first.
How it is evaluated
A single prolactin measurement is usually sufficient -- no dynamic testing needed. Macroprolactin is checked in asymptomatic patients with elevated levels, since it's a inactive, harmless form that can falsely elevate results. MRI is reserved for levels not explained by medication or pregnancy.
Treatment
Dopamine agonists (cabergoline preferred for efficacy and tolerability; bromocriptine preferred when planning pregnancy) are first-line and shrink most prolactinomas effectively. Cabergoline requires a baseline cardiac valve evaluation before starting given a dose-dependent valve-disease signal at high doses.
When to seek care
Visual field loss (occurring in about 27% of macroprolactinoma cases from pressure on the optic chiasm) or sudden severe headache with vision changes (possible pituitary apoplexy) need urgent evaluation.