B-111 Prevalence of Macroprolactinaemia in a Chinese Population: A Comparative Analysis Across Different Prolactin Testing Platforms

Abstract Background Prolactin (PRL) levels are the definitive biochemical indicator of hyperprolactinaemia. However, different PRL immunoassays often exhibit varying degrees of cross-reactivity with macroprolactin, a factor that can result in misdiagnosis and improper treatment. Recent meta-analyses revealed that the global prevalence of macroprolactinaemia varies widely, from 8% to 42%, with an average of 18.9%. Importantly, the prevalence of macroprolactinaemia is closely linked to the ability of PRL immunoassays to detect and differentiate macroprolactin. The objective of this study is to determine the prevalence of macroprolactinaemia among the Chinese population using various PRL immunoassays and to identify the PRL immunoassay that exhibit the highest resistance to macroprolactin interference, thereby being suitable for clinical application. Methods We gathered a total of 148 PRL-negative samples and 346 positive samples, identified by the Abbott Architect PRL assay. Each sample underwent polyethylene glycol (PEG) precipitation treatment. Both the pre-and post-PEG precipitation samples were subsequently analyzed using Mindray, Roche Elecsys , and Beckman Access PRL assays. Samples exhibiting recoveries post-PEG 40% were categorized as having macroprolactin interference, those with recoveries between 40-60% were considered as potentially macroprolactin-interfering, and those with recoveries 60% were deemed non-interfering. Among these, 15 samples with PEG recoveries=60% were chosen for gel chromatography analysis. Results The correlation of samples before and after PEG precipitation is better in the Mindray system (R=0.950) than in the Beckman (R=0.855) and Roche (0.815) systems. The percentage of interfering samples among the positive samples also varied significantly across platforms: 22.3% for Roche,15.3% for Beckman, and 6.1% for Mindray. Roche and Beckman platforms did not find interference in samples with concentrations above 150 ng/mL, while the corresponding value for Mindray platform is 100ng/mL. In the 15 samples that underwent gel chromatography, the Mindray PRL had the smallest absolute deviation from the gold standard gel chromatography (±1.96SD, Mindray: -11.9 to 26.6 ng/mL, Roche: -11.4 to 78.3 ng/mL, Abbott: -67.3 to 258.4 ng/mL, Beckman: -14.9 to 51.7 ng/mL), indicating that the results from Mindray were the closest to those from gel chromatography. Conclusion The prevalence of macroprolactinaemia in the Chinese population is significantly influenced by the PRL immunoassay used. This study demonstrates that the Mindray PRL assay possesses the strongest resistance to macroprolactin interference, thereby enabling more accurate diagnoses of hyperprolactinaemia.