The frequency of macroprolactinemia among patients with hyperprolactinemia in a central laboratory of a training and research hospital.

Objective: Macroprolactinemia is a well-described endocrine disorder, with its results leading to unnecessary tests and overtreatment. However, routine macroprolactin screening is not performed in many laboratories. Routinely used prolactin assays can result in false diagnosis of hyperprolactinemia in patients with no signs and symptoms related to hyperprolactinemia and clinicians should be aware of macroprolactinemia frequency encountered with the method in use. In this study, it was aimed to examine the frequency of macroprolactinemia among patients with hyperprolactinemia.

Methods: Prolactin analyses were performed on Roche Cobas^® e801 immunoanalyzer using the Elecsys Prolactin II electrochemiluminesence immunoassay (Roche Diagnostics, Mannheim, Germany). Samples were provided from 14 different hospitals in total and evaluated with the same method in a single central laboratory. In order to precipitate the samples for macroprolactin analysis, polyethylene glycol (PEG) 6000 was used.

Results: In this study, we evaluated 1100 patients with hyperprolactinemia and determined the frequency of macroprolactinemia to be 9.6% (recovery cut-off value <40%), while 8.5% of the patients were in the gray zone (recovery cut-off value 40% to <60%).

Conclusion: Laboratories should consider regularly screening for macroprolactinemia in all hyperprolactinemic samples and collaborate with clinicians to raise awareness about the prevalence of this condition.