Low prevalence of macroprolactinaemia among patients with hyperprolactinaemia screened using polyethylene glycol 8000

Abstract Objectives Macroprolactinaemia is a known benign cause of hyperprolactinaemia (hyperPRL). Differentiating macroprolactinaemia and hyperPRL is important, as macroprolactinaemia does not require treatment. This study was conducted to determine the prevalence of macroprolactinaemia among hyperPRL patients through the use of polyethylene glycol 8000. Methods From 2011 to 2013, a cross-sectional study was conducted on patients diagnosed with hyperPRL in Hospital Universiti Sains Malaysia (HUSM). Sera from these patients were measured for PRL using cobas e411 (Roche Diagnostics, Indianapolis, USA) (sandwich principle) and the same sera were treated with polyethylene glycol (PEG) 8000 to differentiate true hyperPRL from macroprolactinaemia. PRL recovery of less than 40% was used as an indicator of the presence of macroprolactin. Results A total of 133 hyperPRL patients, 120 (90%) women and 13 (9.8%) men, aged 18–68 years, with mean (standard deviation) age 34.37 (11.75) years comprised this study cohort. Nine female patients were found to have macroprolactinaemia with an estimated prevalence of 6.8% (95% CI: 2.4%, 11.1%). Conclusions The prevalence of macroprolactinaemia detected using PEG 8000 among patients diagnosed as hyperPRL was low. Screening for macroprolactin using PEG 8000 indicated that the majority of patients who presented with hyperPRL in HUSM were true hyperPRL.