Isolated prolactin deficiency associated with serum autoantibodies against prolactin-secreting cells

Context: Isolated prolactin (PRL) deficiency is a rare entity of unknown etiology manifesting as failure of puerperal lactogenesis. Objective: The aim of the study was to determine the cause of isolated PRL deficiency in an affected woman. Design and Setting: We examined genetic and autoimmune causes of isolated PRL deficiency at academic medical centers. Patient: The patient was a 39-year-old woman with puerperal alactogenesis after two deliveries and undetectable PRL. The other pituitary axes, serum calcium levels, and cranial magnetic resonance imaging were normal. Intervention: Recombinant human PRL (r-hPRL) was administered to the patient. Main Outcome Measures: We measured the sequencing of candidate genes and immunofluorescence analysis of autoantibodies directed against pituitary endocrine cells. Results: There were no rare sequence variants in the genes encoding for PRL, putative PRL-releasing peptide, putative PRL-releasing peptide receptor, or in other genes important for lactotroph lineage development (POU1F1, PROP1, LHX3, LHX4, HESX1, OTX2, and LSD1). The patient serum, on the contrary, contained autoantibodies that specifically recognized a subset of PRL-secreting cells but not PRL itself or any other pituitary cells or hormones. The mother was able to lactate fully after 17 days of treatment with r-hPRL 60 jutg/kg every 12 hours, but alactogenesis resumed after treatment was completed. Conclusions: These studies report a new autoimmune etiology for women with isolated PRL deficiency and puerperal alactogenesis.