In 108 patients with nonpuerperal mastitis (inflammatory symptoms of duct ectasia), serum prolactin levels were determined before, during, and after treatment. Twenty-nine patients (26.8%) exhibited transiently elevated prolactin levels during the period of inflammation (mean±SD level, 42 ±22 μg/L that returned to normal within 4 weeks. Twenty-two patients (20.4%) presented with more severe hyperprolactinemia (78 ±56 μg/L), and 15 were found to have pituitary microadenomas. In 11 cases, mastitis was the first symptom of hyperprolactinemia. A second group of 83 patients with known hyperprolactinemia and 83 normoprolactinemic controls were interviewed with regard to recent symptoms or past treatment of nonpuerperal mastitis. Sixteen hyperprolactinemic women (19.3%) and none of the controls reported that they had experienced mastitis. We conclude that duct ectasia is due in part to increased prolactin secretion. Thus, nonpuerperal mastitis may be a symptom of hyperprolactinemia. On the other hand, nonpuerperal mastitis may induce transient hyperprolactinemia (neurogenic hyperprolactinemia) of about 3 weeks' duration that is less pronounced than central hyperprolactinemia.
Peters F, Schuth W. Hyperprolactinemia and Nonpuerperal Mastitis (Duct Ectasia). JAMA. 1989;261(11):1618–1620. doi:10.1001/jama.1989.03420110094030