The Clinical Characteristics of Macroprolactinemia

Abstract

Background: Prolactin has been identified by gel chromatography to exist is three different forms in human serum; monomeric prolactin (molecular mass 23 kDa), big prolactin (molecular mass 50~60 kDa) and big big prolactin, otherwise known as macroprolactin (molecular mass 150~170 kDa). The predominance of macroprolactinemia has long been known in idiopathic hyperprolactinemic patients with maintained fertility. In recent reports, 24% of microprolactinoma patients showed no menstrual disturbances, which was suggestive of macroprolactinemia. The purpose of this study was to evaluate: (1) the frequency of macroprolactinemia among idiopathic hyperprolactinemia and prolactinoma patients, (2) the difference in the clinical characteristics between hyperprolactinemia, with and without macroprolactinemia, among idiopathic hyperprolactinemia and prolactinoma patients, and (3) the follow-up prolactin level using the bromocriptine response. Methods: We retrospectively analyzed the clinical characteristics and prolactin levels in 43 idiopathic hyperprolactinemia and 51 prolactinoma patients with a poor bromocriptine response. Macroprolactinemia was identified by the prolactin recovery of < 40% using the polyethylene glycol (PEG) precipitation test. Results: (1) Of the 43 idiopathic hyperprolactinemia and 51 prolactinoma patients, 17 (39.5%) and 9 (17.6%), respectively, were macroprolactinemic (P < 0.05). (2) Among the idiopathic hyperprolactinemia patients, galactorrhea combined with amenorrhea was significantly less frequent (P < 0.05), with the 1- and 2-year follow-up prolactin levels being significantly higher in those with macroprolactinemia than monomeric prolactinemia (P <0 .05). (3) Among the prolactinoma patients, amenorrhea was significantly less frequent (P < 0.05), but asymptomatic cases were more frequent in those with macroprolactinemia than monomeric prolactinemia (P < 0.05). The 1and 2-year follow-up prolactin levels were significantly higher in those with macroprolactinemia than monomeric prolactinemia (P < 0.05). Conclusion: The screening of macroprolactinemia should be considered in idiopathic hyperprolactinemia and prolactinoma patients with a poor bromocriptine response (J Kor Soc Endocrinol 20:216～223, 2005).