Frequency of macroprolactinaemia in pregnant women

Prolactin (PRL) is a 198 polypeptide hormone involved in many biological functions in women. The main role of PRL is primarily associated with lactation and breast development. There are 3 isoforms of PRL: the little (23 kDa), the big (50-60 kDa) and the big-big also named macroprolactin (> 100 kDa). Macroprolactin was described for the first time nearly 30 years ago but the structure of the complex is still unclear. Macroprolactin is reported a large complex consisted of monomeric PRL and mainly immunoglobulin G. The aim of the study was to estimate frequency of macroprolactinaemia in normal pregnant women in the third trimester. Clinical study included 300 healthy pregnant women between 24 and the 28 weeks of gestation. Serum PRL concentration was measured using ELISA method. Prolactin recovery was estimated with the use of polyethylene glycol (PEG) precipitation. We demonstrated that 3% of 300 pregnant women in the third trimester of pregnancy presented macroprolactinaemia. In conclusion, macroprolactinaemia occurs also in healthy pregnant women but in very low percent.