During pregnancy of healthy women, a great increase of serum little prolactin occurs. In has been also reported that a significant amount of serum big big prolactin (termed macroprolactinemia) may be detected in about 4% of healthy pregnant women. Because the occurrence of macroprolactinemia during pregnancy of women with prolactin-producing pituitary microadenomas has not been extensively investigated, we determined both little and big big prolactin in serum of 97 women with prolactin-producing pituitary microadenomas who became pregnant after bromocriptine treatment. In all patients bromocriptine was discontinued during the first 12 weeks of pregnancy, and blood samples were obtained for prolactin measurements from the 6th until the 13th week of pregnancy (trimester I), from the 14th until the 27th week (trimester II) and from the 27th week until delivery (trimester III). Total prolactin (assayed directly) and little prolactin (measured following polyethylene glycol precipitation) were determined using an ECLIA assay (Elecsys 2010, Roche), and the samples were considered to contain significantly large amounts of macroprolactin when the proportion of little prolactin was less than 55% of total prolactin. Of the 97 women, 84 had negligible amount of macroprolactin in each of the three period of sampling (serum total and little prolactin in trimester I, mean±S.D., 88±55 and 80±54 ng/ml, respectively; in trimester II, 150±61 and 143±62 ng/ml, respectively; in trimester III, 196±76 and 186±73 ng/ml, respectively). In contrast, a significantly large amount of macroprolactin (corresponding to >45% of total prolactin) was found in 13 women, in whom total prolactin (mean±S.D. in trimester I, II, and III, 174±183, 281±148 and 368±61 ng/ml, respectively), but not little prolactin levels (mean±S.D. in trimester I, II and III 54±44, 100±52 and 146±46 ng/ml, respectively) were significantly higher than the corresponding values in woman without significant macroprolactinemia. We conclude that a significant macroprolactinemia, associated with a significant increase of total prolactin, occurs in 12% of women with prolactin-producing microadenomas during pregnancy.
01 - 05 Apr 2006
European Society of Endocrinology