Prevalence and re-evaluation of macroprolactinemia in hyperprolactinemic patients: A retrospective study in the Turkish population

Abstract

Objectives: This study aimed to investigate the prevalence of macroprolactinemia and the changes in hyperprolactinemia status over time among hyperprolactinemic patients in the Turkish population. Methods: A retrospective study was conducted on 3,013 patient records from a central university hospital between October 2023 and October 2024. Of these, 634 hyperprolactinemic samples (Prolactin >15.2 mu g/L in males, >23.3 mu g/L in females) were analyzed using polyethylene glycol (PEG) precipitation method. Post-PEG prolactin levels were measured using electrochemiluminescence immunoassay, with the recovery percentage (R%) calculated as the ratio of prolactin post-PEG precipitation to total prolactin, where R% values below 40 % were indicative of macroprolactinemia. The change in R% values was analyzed in 63 hyperprolactinemic patients who underwent restesting. Results: Macroprolactinemia prevalence was found as 5.67 % of hyperprolactinemic patients with no macroprolactinemia cases observed at PRL levels above 85.40 mu g/L. Male patients had significantly higher R% values than females (p=0.003). In the gray zone (R%: 40-60), 29.03 % of patients were classified as truly hyperprolactinemic. Repeated tests after an average of four months showed stable R% values in most cases, with only two patients changing classification between macroprolactinemia and true hyperprolactinemia. Conclusions: The prevalence of macroprolactinemia in hyperprolactinemic Turkish patients was relatively low. As prolactin values increase, true hyperprolactinemia is more commenly observed instead of macroprolactinemia. Short-term retesting for macroprolactinemia may not be necessary unless clinical conditions change significantly. Accurate diagnosis requires method-specific cutoffs and further prospective studies using gold-standard methods like gel filtration chromatography.