Original scientific paper

https://doi.org/10.11613/BM.2019.020706

Optimizing laboratory defined macroprolactin algorithm

Milica Šostarić orcid.org/0000-0003-1760-2852 ; Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia
Adriana Bokulić orcid.org/0000-0002-0795-3547 ; Laboratory of Endocrinology, Clinic of Oncology and Nuclear Medicine, Sestre Milosrdnice University Hospital Center, Zagreb, Croatia
Domagoj Marijančević orcid.org/0000-0002-1735-1865 ; Laboratory of Endocrinology, Clinic of Oncology and Nuclear Medicine, Sestre Milosrdnice University Hospital Center, Zagreb, Croatia
Ivana Zec ; Laboratory of Endocrinology, Clinic of Oncology and Nuclear Medicine, Sestre Milosrdnice University Hospital Center, Zagreb, Croatia

Abstract

Introduction: Macroprolactinaemia is a well-known analytical problem in diagnostics of hyperprolactinaemia usually detected with polyethylene
glycol (PEG) precipitation method. Since there is no harmonization in macroprolactin detection and reporting results, this study proposes and evaluates the usefulness of in-house developed algorithm. The aims were to determine the most suitable way of reporting results after PEG treatment and the possibilities of rationalizing the precipitation procedure.
Materials and methods: This is a retrospective study based on extracted data for 1136 patients. Prolactin concentrations were measured before
and after PEG precipitation on Roche cobas e601. Macroprolactinaemia was defined by percentage recovery and post-PEG prolactin concentrations.
Results: Prevalence of macroprolactinaemia using recovery criteria of ≤ 40%, ≤ 60%, and post-PEG prolactin concentrations was 3.3%, 8.8% and 7.8%, respectively. Raising the cut-off value from the upper limit of the manufacturer’s reference interval to 32.9 μg/L does not drastically change detected macroprolactinaemia with recovery criteria. Post-PEG prolactin concentrations showed more than half of the patients with macroprolactinaemia would be overlooked. Regardless of the criteria, a cut-off of 47.0 μg/L would miss most of the macroprolactinaemic patients. Repeated recovery measurements of follow-up patients showed there is a significant difference with mean absolute bias of 9%.
Conclusions: Post-PEG prolactin concentration with corresponding reference interval is the most suitable way of reporting results. All samples with prolactin concentration above the upper limit of the manufacturer’s reference interval should be submitted to PEG precipitation. Follow-up period could be prolonged since the difference between the recoveries of repeated measurements is not clinically significant.

Keywords

prolactin; hyperprolactinaemia; macroprolactin; polyethylene glycol

Hrčak ID:

221078

URI

https://hrcak.srce.hr/221078

Publication date:

15.6.2019.

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