Raised prolactin levels in myasthenia gravis: two case reports and a study of two patient populations.

OBJECTIVES: To describe two patients with myasthenia gravis (MG) and prolactinoma and analyze the associations between MG and prolactin (PRL) levels. DESIGN: Two case reports and a case-control study of PRL levels in 192 patients with MG. PARTICIPANTS: The Immunological Research Laboratory, Center for Molecular Medicine, Department of Medicine and the Department of Neurology, Karolinska Institutet, Stockholm, Sweden; St Petersburg Medical Academy for Postgraduate Studies, and St Petersburg State Medical Pediatric Academy, Russia. RESULTS: Two women with MG and thymic hyperplasia accompanied by prolactinomas are described. The levels of plasma PRL were raised in 101 women with MG, but not in 91 men. There was an association between high PRL levels and high levels of autoantibodies against the acetylcholine receptor. CONCLUSIONS: There is an association of MG with raised levels of PRL in women. PRL has stimulating effects on immune activation and the increased levels might thus be implied in the pathophysiology of MG.