Macroprolactin on the Advia Centaur: experience with 409 patients over a three-year period

Abstract

Introduction: Macroprolactin (MPRL) is an important source of interference that may lead to misdiagnosis and mismanagement of hyperprolactinaemic patients. Prolactin assays exhibit considerable variation in the detection of MPRL. In this study, we examine the requirement for polyethylene glycol (PEG) precipitation in the analysis of hyperprolactinaemia detected by the Advia Centaur as it has a relatively low reactivity with MPRL. Methods: Four hundreds and sixty-four hyperprolactinaemic samples were collected from the laboratory information system for Saint James University Hospital over a three-year period. These samples were screened for MPRL using PEG precipitation protocol. Monomeric prolactin concentration post-PEG precipitation was compared with a reference range determined by PEG precipitation in normal subjects. Results: MPRL was the cause of hyperprolactinaemia in 4% of patients (16/409) over the three-year period studied. Nine subjects with MPRL also had elevated monomeric prolactin. Conclusions: PEG screening is still needed for assays with low MPRL reactivity such as the Advia Centaur and this should be performed with a locally derived reference range for monomeric prolactin.

Variation of female prolactin levels with menopausal status and phase of menstrual cycle

“…Patients with pronounced elevation in prolactin, those with TSH outside the laboratory’s reference interval and pregnant women were excluded from the study to avoid inclusion of obvious biases in prolactin data. Patients with macroprolactin and other causes of mildly increased prolactin were not excluded, but these are likely to have a minimal effect given the large number of patients and the low incidence of macroprolactin (<5% of hyperprolactinaemia using the Siemens method) 6,7 . The presence of macroprolactin is likely to have affected all groups equally and thus would not affect the differences found between the groups.…”

Analytical error and interference in immunoassay: minimizing risk

“…4% for one such immunoassay, although 9 of the 16 patients whose serum samples contained macroprolactin also had raised monomeric prolactin). 37 Screening for macroprolactin in all serum specimens with total prolactin concentrations above an agreed cut-off is therefore widely recommended.…”

Hyperprolactinaemia caused by antipsychotic drugs: a new application for prolactin assays

“…This is illustrated in a recent report that indicated that 25% of prolactin requests came from psychiatry. 4 …”