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

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 μg/L in males, >23.3 μg/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 μg/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.