Background: Apart from the rare association with type I multiple endocrine neoplasia (MEN-1), familial types of prolactinoma have not been reported.
Patients and measurements: Eight hyperprolactinaemic patients in four families and 18 of their first and second-degree relatives (parents, children and grandchildren) were examined. Hormone levels were measured, as well as other biochemical parameters.
Results: Prolactinoma was diagnosed in more than one member of each of the four families.
Conclusion: Familial prolactinoma is a distinct entity which is probably due to a genetic mutation promoting lactotroph proliferation.