Prevalence of Macroprolactinemia in Patients with Hyperprolactinemia Using Roche Elecsys Platform in a Large Tertiary Referral Center in UAE

<b><i>Objectives:</i></b> Macroprolactin (macroPRL) excess is an important cause of hyperprolactinemia. Several prolactin assays have high reactivity to macroPRL. However, macroPRL screening is not routinely performed in many labs. This study aimed to evaluate the prevalence of macroprolactinemia (MP) in patients with elevated prolactin using the Roche Elecsys assay in a large tertiary center in UAE. <b><i>Materials and Methods:</i></b> Consecutive samples of patients with elevated prolactin presenting to Tawam Hospital from June to August 2018 were evaluated for MP. Polyethylene glycol (PEG) was used to precipitate macroPRL. Monomeric prolactin recovery cutoff ≤50% was used to determine the prevalence of MP. <b><i>Results:</i></b> A total of 180 patients with elevated prolactin were included in the study with a mean age of 33.1 ± 11.9 years. The majority were women (87.2%), and about 77.8% were newly diagnosed patients with hyperprolactinemia. The main indications for prolactin testing were menstrual irregularity (<i>n</i> = 121), infertility (<i>n</i> = 11), galactorrhea (<i>n</i> = 11), and sellar masses (<i>n</i> = 12). MP was present in 8.3% of the patients. The median (IQR) of total prolactin level was 740.5 (579–1,085) IU/m before PEG precipitation and was not significantly different between MP and true hyperprolactinemia cases. Three patients with MP had pituitary MRI evaluation, which was normal. Eight patients with MP were treated with cabergoline. <b><i>Conclusion:</i></b> One in 12 patients with hyperprolactinemia had MP on the Roche Elecsys assay defined as the cutoff recovery of ≤50% post-PEG precipitation. Physicians should be aware of the prolactin assay used in their labs, and we recommend routine macroPRL assessment in mild hyperprolactinemia samples in labs using the Roche Elecsys platform.