Endocrine Abstracts

Macroprolactin interference is a common problem in the interpretation of immunoassays for prolactin. Identifying macroprolactinemia can prevent errors in diagnosis and subsequent delivery of treatment to patients. The search for macroprolactin through polyethylene glycol (PEG) precipitation followed by percentage recovery is the most common used method in clinical laboratories. This study aimed to evaluate the implementation of macroprolactin assessment in hyperprolactinemic samples, with the interpretation of the results based on validated post-PEG monomeric prolactin reference range. It also aimed to verify whether post-PEG monomeric prolactin measurements could match the results obtained through Gel filtration chromatography (GFC). Samples from 40 healthy subjects were utilized for the validation of the post-PEG monomeric prolactin reference range, according to predetermined data quality. The macroprolactin assessment by PEG precipitation was then performed on 112 hyperprolactinemic samples (96 women), and results obtained by percentage of post-PEG prolactin recovery were compared with post-PEG monomeric prolactin concentrations. Twenty-five out of the 112 hyperprolactinemic samples were randomly selected for evaluation through GFC for further comparisons. Assessment of post-PEG monomeric prolactin concentration with an appropriate validated reference range showed greater specificity than the conventional criterion of percentage of post-PEG prolactin recovery, as it identified samples with both excess macroprolactin and monomeric bioactive prolactin, and also reduced the rate of indeterminate results. Furthermore, most of the results obtained in samples analyzed by GFC were in agreement with results obtained by post-PEG monomeric prolactin measurement. The assessment of macroprolactin through a validated post-PEG monomeric prolactin reference range should be adopted as it outperformed the current utilized criterion.