Prolactin deficiency in the context of other pituitary hormone abnormalities : Special issue: hypoprolactinemia: a neglected endocrine disorder.

Prolactin deficiency is rare. It generally occurs when pituitary disorders, such as large pituitary tumors, pituitary apoplexy, and other conditions associated with sellar mass effect lead to global failure of pituitary function and hypopituitarism. In these situiations, prolactin is commonly the last pituitary hormone affected, after growth hormone and gonadotropins are lost and thyroid-stimulating hormone and adrenocorticotopic hormone secretion is impaired. Prolactin deficiency accompanies several congenital syndromes due to mutations in PROP1 and Pit1/ POU1F and in X-linked IGSF1 deficiency syndrome, and several aqcuired conditions including Sheehan syndrome, IgG4-related hypophysitis, and immune checkpoint-inhibitor-induced hypophysitis. In women, prolactin deficiency prevents lactation following childbirth among other symptoms associated with hypopituitarism. Human prolactin is not available commercially as replacement therapy. However, recombinant human prolactin administered daily to women with hypoprolactinemia and alactogenesis was found to lead to the production of significant milk volume sufficient for lactation.