Macroprolactinemia, a variety of hyperprolactinemia. Apropos of 5 cases

Macroprolactinemia, due to increased circulating levels of large molecular weight forms of prolactin, results in elevated level of immuno-reactive prolactin. The big variants have only weak biological activity; thus macroprolactinemia appears as a case of hyperprolactinemia without clinical significance as demonstrated by the five patients described. The diagnosis is based upon chromatography which separates the hormone and its variants. This disorder produces a pitfall in the diagnostic evaluation of hyperprolactinemia.