Endocrine Abstracts

JOINT3062

Introduction: Macroprolactinaemia is a well-known analytical problem in the diagnostics of hyperprolactinaemia, usually detected with the polyethylene glycol (PEG) precipitation method. Due to the lack of harmonization in macroprolactin detection and reporting results, this study proposes and evaluates the usefulness of an in-house-developed algorithm. This study aimed to assess whether repeating the PEG precipitation resulted in any difference in recovery and explore the potential for rationalizing the precipitation procedure.

Materials and Method: This is a retrospective study based on extracted data for 547 follow-up patients, of which 453 (83%) were women and 94 (17%) were men. All patients with prolactin concentration above the upper reference limit defined by the manufacturer (women: 23.3 μg/l; men: 15.2 μg/l) were included in the study according to the in-house algorithm. Prolactin concentrations were measured before and after PEG precipitation on the Roche cobas e801 analyser (Roche Diagnostics GmbH, Mannheim, Germany) using the Elecsys Prolactin II sandwich electrochemiluminescence immunoassay. Macroprolactinaemia was defined based on the percentage recovery of prolactin (%Recovery), calculated using the total prolactin (PRL) and the post-PEG prolactin concentration (%Recovery = 100 x PRL/post-PEG prolactin). The normality of data distribution was tested with the D’Agostino-Pearson test. The Wilcoxon rank-sum test was employed to determine the difference between the recoveries of repeated measurements. %Recovery data and the interval between repeated measurements were expressed as median and interquartile range.

Results: %Recovery for the total prolactin concentration was 84 (75-87) %, which was nearly identical to the repeated measurement at 84 (75-88) %. Analysis of the %Recovery data from repeated measurements in follow-up patients (n = 547) showed no significant difference (P = 0.247). The median interval between repeated measurements was 2.1 (1.2-3.1) years.

Conclusion: Our results demonstrated no statistically significant difference in recovery values between repeated measurements, indicating that the PEG precipitation protocol could be simplified by prolonging the follow-up period. Although the exact pathogenesis of macroprolactinaemia remains unknown, it is regarded as a benign and long-lasting condition consistent with this study’s findings.