MIDCYCLE INCREASE OF PROLACTIN SEEN IN NORMAL WOMEN IS ABSENT IN SUBJECTS WITH UNEXPLAINED INFERTILITY

Objective: To compare the bioactive and immunoactive PRL in normal and unexplained infertility subjects. Design: Prospective study. Setting: Department of Obstetrics and Gynecology, Wayne State University and T he University of Michigan. Patient(s): Twelve normal, fertile women co mpared with 12 patients with unexplained infertility. Intervention(s): Serum samples were obtained across the menstrual cycle and for each s ubject, 5 pools were prepared by combining serum aliquots from the ear ly follicular, late follicular, midcycle, and midluteal and late lutea l phases of the cycle. Main Outcome Measure(s): Niobium lymphoma cell bioassay and an immunoradiometric assay were used to quantitate PRL. R esult(s): A midcycle increase in PRL was seen in controls by both assa ys and these levels were greater compared with other cycle stages. Com parison of midcycle PRL between groups showed differences only between bioactive PRL (34.2 +/- 8.3 versus 19.2 +/- 3.4 ng/mL [conversion fac tor to SI unit, 1.00]). The ratios between bioactive and immunoactive PRL were comparable, Significant correlation between bioactive and imm unoactive PRL was seen for both control (r = 0.616) and unexplained in fertility (r = 0.660) groups. Conclusion(s): The midcycle elevations o f bioactive and immunoactive PRL seen in normal women were absent in w omen with unexplained infertility. This alteration in PRL dynamics may be a part of subtle differences in the reproductive hormone profile o f women with unexplained infertility compared with their fertile count erparts. (C) 1997 by American Society for Reproductive Medicine.