Endocrine Abstracts

The incidence of macroprolactinemia decreased notably because of wide use of prolactin (PRL) assays measuring macroprolactin at a lower rate. However, in case of high PRL levels, measurement of monomeric PRL (mPRL) levels after polyethylene glycol (PEG) treatment is still required. Our aim was to determine – by the use of a second generation PRL assay – how total PRL (tPRL) levels in native sera of healthy blood donors change after PEG treatment. In women, the use of oral contraceptives (OC) was taken into consideration as well.

Methods: PRL levels were determined in 131 healthy blood donors (50 men and 81 women; age 33.5±10.5 years). Forty-one women were taking OC. tPRL was measured before and after PEG treatment with a fully automated method (ECLIA, Cobas e411, Roche). PRL recovery (PRL-r%) was determined as the quotient of mPRL/tPRL.

Results: There were increased tPRL levels in 16 native sera (11%). PRL levels after PEG treatment decreased into the reference range only in two of these cases. The other 14 women had mild true hyperprolactinemia (558±238 mU/l), 12 of them took OC. tPRL levels were significantly (P<0.05) higher in women than in men (312±224 vs 235±140 mU/l, respectively), but there were no significant differences in mPRL levels (255±173 vs 223±126 mU/l). PRL-r% was higher (P<0.001) in men than in the two groups of women. There was a significant, albeit week positive (r=0.24; P<0.01) correlation between age and PRLr %. There was no significant difference in the PRL levels between women taking or not taking OC.

Conclusions: According to our results the incidence of macroprolactinemia among healthy blood donors is only 1.5%. In women taking OC only true hyperprolactinemia was present. The weak, but significant positive correlation between age and PRLr% proves the increased antibody production during ageing.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.