Observational studies on macroprolactin in a routine clinical laboratory

Abstract

The presence of macroprolactin can change over time and we cannot advise that once a test for macroprolactinemia has been performed that it is not necessary to repeat the investigation if a subsequent sample is hyperprolactinemic; nor can one assume that macroprolactin will not develop even if it has been excluded previously.

Assessment of intraindividual agreement in prolactin results after post-polyethylene glycol precipitation test for the estimation of macroprolactin. Should the precipitation procedure be repeated in the same patient?

“…We have 790 patients with multiple by PEG precipitation test in the four-year period studied (Figure 1). The concordance of repeated measurements of MCPRL in the same patient was very high: 96.2% of the patients had concordance (either a positive or a negative MCPRL) in all their determinations, but 30 patients (3.8%) had discordant results, in accordance with others [7,8]. If we consider, like others, that a recovery between 40 and 60% is a gray or borderline zone instead of considering a single cut-off point of 50, only three out of 790 patients (0.38%) would have been discordant with results below 40% and above 60%.…”

“…There is no general agreement that establishes a single cut-off but the most commonly used are 40 and 50. Most authors consider a positive MCPRL if recoveries <40% and a negative macroprolactin if recoveries >60 [5][6][7]. However, more than the fact that a subject is classified as being MCPRL positive or negative, the important thing to the clinician is whether the monomeric prolactin calculated post-PEG is within the limits of normality, since this measurement will give information about whether bioactive prolactin is within the normal range or if it is high [3,8].…”

“…Performing a PEG precipitation in all samples with prolactin above the upper reference range leads to a high workload in the laboratory, due to repeatedly high prolactin results in the same patient. In order to reduce the total amount of macroprolactin measurements some authors have suggested rationalizing the precipitation procedure by increasing the prolactin concentration from the upper limit of normality to higher values [7]. However, with these criteria some patients with macroprolactinemia would be overlooked [4].…”

Cardiometabolic Risk Factors in Men with Elevated Macroprolactin Content: A Pilot Study

“…Moreover, the measurements of total prolactin, big-big prolactin and cardiometabolic risk factors were carried out twice in time intervals of at least 6 months. Although macroprolactinemia is usually a longterm finding, in some cases it remits [25]. Therefore, performing two measurements separated in time allowed us to minimize the possibility that macroprolactinemia in the study population was a temporary condition.…”

Establishment of Reference Intervals of Monomeric Prolactin To Identify Macroprolactinemia in Chinese Patients with Increased Total Prolactin

“…This commonly results in misdiagnosis and mismanagement of patients, as well as wasted healthcare resources and unnecessary concern from both patients and clinicians [6]. High concentrations of macroprolactin appears to result from reduced clearance of antigen-antibody complexes of monomeric prolactin and immunoglobulin G. These complexes interfere with the interaction between prolactin and the capture and detection antibodies involved in the sandwich reaction of prolactin immunoassays [7,8]. Consequently, it is essential for clinical laboratories to establish screening methods to detect macroprolactin and the monomeric prolactin component in all hyperprolactinemic serum samples [9].…”