Determination of incidence of macroprolactinemia in hyperprolactinemia by Poly Ethylen Glycol and evaluation of its clinical and radiological findings

Prolactin exists in 3 different molecular forms, i.e., monomeric, big and at times big big (macroprolactine) in human serum. Macroprolactine is a complex of prolactine and IgG and may account for a significant proportion of idiopathic hyperprolactinemia. Its biological activity is considered low or absent, but it is measured by the common immunoassay method, thus can lead to expensive explorations and ineffective treatments. Conventionally the diagnosis of macroprolactinemia has been done by Gel Filtration Chromatography, which cannot be used routinely. Recently Poly Ethylene Glycol has been employed to precipitate macroprolactine, allowing its rapid detection, dependably and inexpensively. The objective of the present work is to assess the incidence of macroprolactinemia in patients with hyperprolactinemia, by its identification with PEG, and to establish the clinical (galactorrhea and oligomenorrhea) and radiological findings (sella MRI) of such a cohort. 50 patients with hyperprolactinemia were investigated for macroprolactine. Prolactine was measured before and after precipitation of macroprolactine by PEG, with recovery of <= 40% taken as indicating significant macrorprolactinemia. Macroprolactine was found in 14(28%) patients. In true hyperprolactinemic patients (36 patients) galactorrhea occurred in 59.4%, and oligomenorrhea occurred in 65.6% of patients, but in macroprolactinemic patients, galactorrhea occurred in 8.3% and oligomenorrhea occurred in 25% of patients. Also normal pituitary images were found in 41.2% of patients who had true hyperprolactinemia and in 85.7% of patients with macroprolactinemia.