Optimization of PEG precipitation for macroprolactinemia screening.

Authors

Naoki Hattori, Norito Nishiyama, Takanori Saito, Mitsuhiro Morita

Published in

Clinical chemistry and laboratory medicine. Nov 13, 2026. Epub Nov 13, 2026.

Abstract

To determine whether 20 % or 25 % polyethylene glycol 6000 (PEG) is more suitable for macroprolactinemia screening and to investigate methodological factors affecting PEG precipitation.
Serum samples from five individuals with macroprolactinemia and five hyperprolactinemic controls were analyzed. Gel filtration chromatography quantified the precipitation of individual prolactin (PRL) molecular forms. Nonspecific monomeric PRL precipitation was assessed using an artificial serum matrix. Incubation time, temperature, pH, and PEG solvent were also investigated.
In the artificial serum matrix, monomeric PRL precipitation was significantly lower with 20 % than with 25 % PEG (29.3 ± 5.0 % vs. 39.2 ± 6.2 %; p=0.0053). In macroprolactinemic sera, both PEG concentrations precipitated more than 90 % of macroPRL and big PRL, with no significant differences between the two concentrations. However, monomeric PRL precipitation was significantly lower with 20 % than with 25 % PEG (28.5 ± 9.4 % vs. 39.8 ± 11.0 %; p=0.0033). Despite this difference, the proportions of monomeric PRL in the PEG precipitates differed by only 3.0 percentage points. Incubation time and temperature had limited effects on the signal-to-noise ratio. Increasing pH reduced precipitation rates without substantially altering this ratio. A 0.1 mol/L phosphate buffer at pH 7.0 maintained higher precipitation rates in alkalinized, long-term-stored serum samples.
Both PEG concentrations efficiently precipitated macroPRL and big PRL, whereas 20 % PEG reduced nonspecific monomeric PRL precipitation and may be preferable for macroprolactinemia screening. A 0.1 mol/L phosphate buffer at pH 7.0 may be advantageous as a PEG solvent for analyzing alkalinized, long-term-stored serum samples.

PMID:
43018388
Bibliographic data and abstract were imported from PubMed on 12 Nov 2026.

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