Endocrine Abstracts

Aim: To assess the contribution of macroprolactin (macroPRL) to high serum prolactin (PRL) levels and association of prolactin and macroprolactin levels with thyroid status and thyroid autoimmunity during pregnancy.

Methods: Pregnant women (n=138) who had undergone a thyroid-stimulating hormone (TSH) screening during the first trimester of pregnancy enrolled in the study. Serum prolactin, macroprolactin, TSH, FT4, FT3, and thyroid autoantibodies were studied. Selected patients were divided into three groups; group 1 euthyroidsm (n 40: TSH between 0.1 and 2.5 μIU/l), group 2 hypothyroidism (n 54: TSH≧2.51 μIU/l), and group 3 hyperthyroid (n 44: TSH≤0.09 μIU/l). The level of TPOAb ≧35 U/ml has been considered as antibody positive. Polyethylene glycol (PEG) precipitation method was used for detection of macroprolactin and the percentage of monomeric prolactin recovery (monoPRL%) after PEG treatment 40% or less is considered as macroprolactinaemia.

Results: Macroprolactinaemia was found only in two patients (1.4%). One of these patients was euthyroid while the other one was hypothyroid and basal prolactin levels in these patients were 400 and 403 ng/ml respectively. Due to small number of macroprolactinaemia, percentage of their monoPRL recovery was used to compare prolactin homogeneity in other patients. Referring to the whole patients; there was no correlation between PRL, macroPRL or monoPRL% with thyroid hormone status and thyroid antibodies (P>0.05). A positive correlation was observed between the serum levels of PRL with TSH (P=0.014 and r=0.219), while negative correlation was found with FT4 (P=0.011 and r=−0.227).

Conclusions: There were no significant contributions of macroprolactin to prolactin levels during pregnancy. The levels of prolactin showed strong homogeneity and no correlation were found with thyroid dysfunction and thyroid autoimmunity at that time. This uncertainty persisted when correlation analyses done with monoPRL % instead of macroPRL. Eventually we couldn’t find any relationship between thyroid hormones and antibodies with prolactin types in terms of molecular size.