Abstract Objective Macroprolactinemia is an important cause of hyperprolactinemia. The aim of this study was to examine the added value of the consideration of modified reference range in determination of macroprolactinemia and true hyperprolactinemia. Materials and methods Three hundred and ninety patients with high and 131 with normal prolactin (PRL) levels were included in this study. PRL had been analyzed before and after polyethylene glycol precipitation (post-PEG PRL). Recovery percentage (R%) <40% and >60% had been reported as macroprolactinemia and true hyperprolactinemia, respectively. Post-PEG PRL levels were evaluated according to the modified reference range obtained from those of the normoprolactinemic subjects. Results According to the R% criterion; macroprolactinemia had been detected in 24.9% and true hyperprolactinemia in 67.4% of hyperprolactinemic patients. When the data were evaluated considering the post-PEG PRL levels according to the modified reference range; 13 (13.4%) of the 97 macroprolactinemia reports would be considered as true hyperprolactinemia and 6 (2.3%) of the 263 true hyperprolactinemia reports would be changed as macroprolactinemia. Conclusion Discrimination capacity of R% criterion for true hyperprolactinemia and macroprolactinemia is limited, and we suggest that, in accordance with R% criterion, laboratory reports should include the post-PEG PRL levels along with the modified reference range.