ECE2017 Eposter Presentations: Pituitary and Neuroendocrinology Pituitary - Clinical (145 abstracts)
Endocrinology Research Centre, Moscow, Russia.
Introduction: Prolactin exists in various forms including the monomeric biologically active form (23 kDa) and a higher molecular weight form, bound most commonly to IgG, known as macroprolactin (>100 kDa). Macroprolactin lacks biological activity but can interfere in standard prolactin immunoassays and is one of the causes of false-positive results. In Russian Federation the most common method for macroprolactin determination is PEG precipitation test.
Aim: The aim of the study was an evaluation of the monomeric prolactin level measured by two methods: immunochemiluminescent (Cobas 6000) with manual PEG precipitation and immunofluorescent method (Brahms Cryptor).
Materials and methods: We had conducted a retrospective analysis of 41 samples of patients with hyperprolactinemia (3 of them were males). The mean age was 32±2.1 years. Prolactin was measured by the immune chemiluminescent (after PEG precipitation) and immunofluorescent methods.
Results: The mean values found by immune chemiluminescent method with manual PEG precipitation were 460.0 [334.0;807.2] mU/l, by immunofluorescent 432,4 [338.8;700.0] mU/l. The number of patients with intrareference prolactin levels was 41% (17) for the first method and 48.8% (20) for the second one. At the same time, six patients with equivocal results received by immune chemiluminescent method and PEG precipitation had normal prolactin levels by immunofluorescent method. The phenomenon of macroprolactinemia without elevated level of monomeric prolactin was registered in 24.4% (10) of patients. In one person of this group with clinical features of hyperprolactinemia, the increased hormone levels was revealed by Cryptor analyzer.
Conclusion: Measurements of prolactin levels by the immunofluorescent method is useful for correct diagnosis in patients with equivocal results received by immune chemiluminescent method with PEG precipitation.