Objective: To further elucidate the origin of the physiological CA-125 amounts that lead to cyclic changes in CA-125 serum levels in normally menstruating women.
Design: Fifty-three normal endometria, 13 fallopian tubes, 25 ovaries, and nine isolated corpora lutea were prospectively investigated for their CA-125 content in a sandwich solid-phase RIA and by immunohistochemistry. In addition, endometrial CA-125 tissue content was compared with the actual CA-125 serum levels of the study patients.
Results: Cytosolic CA-125 concentrations were 20-fold and twofold higher in the endometrium than those measured in the ovary and the fallopian tube, respectively. Moreover, only in the endometrium did CA-125 content show significant cyclic changes, with the highest concentrations during the early proliferative and middle secretory phase. The lowest tissue concentrations were measured during the early secretory phase. Furthermore, during the early and middle secretory phases cytosolic CA-125 was negatively associated with CA-125 serum levels. In immunohistochemistry, marked distributional changes in OC-125 reactivity were revealed in the basalis and the functionalis throughout the menstrual cycle and the postovulatory loss of CA-125 expression was found to be strongly connected with early secretory transformation of glandular epithelium.
Conclusion: Our findings indicate that the CA-125 amounts responsible for cyclic changes in serum levels in normally menstruating women seem to be a product of normal endometrium.