Hypoprolactinemia is a medical condition characterized by a deficiency in the serum levels of the hypothalamic-pituitary hormone prolactin.

[1][2] Hypoprolactinemia is associated with ovarian dysfunction in women,[3][4] and, in men, metabolic syndrome,[5] anxiety symptoms,[5] arteriogenic erectile dysfunction,[6] premature ejaculation,[5] oligozoospermia (low concentration of sperm in semen), asthenospermia (reduced sperm motility), hypofunction of seminal vesicles, and hypoandrogenism.

[1][9][10] Hypoprolactinemia can result from autoimmune disease,[2] hypopituitarism,[1] growth hormone deficiency,[2] hypothyroidism,[2] excessive dopamine action in the tuberoinfundibular pathway and/or the anterior pituitary, and ingestion of drugs that activate the D2 receptor, such as direct D2 receptor agonists like bromocriptine and pergolide, and indirect D2 receptor activators like amphetamines (through the induction of dopamine release).

[11] Guidelines for diagnosing hypoprolactinemia are defined as prolactin levels below 3 μg/L in women,[3][4] and 5 μg/L in men.

Women who are diagnosed with hypoprolactinemia following lactation failure are typically advised to formula feed, although treatment with metoclopramide has been shown to increase milk supply in clinical studies.