Klein T A, Mishell D R
Am J Obstet Gynecol. 1977 Nov 15;129(6):626-8. doi: 10.1016/0002-9378(77)90643-3.
Daily measurements of human chorionic gonadotropin (HCG) beta subunit, luteinizing hormone (LH), and progesterone were carried out in 24 subjects wearing intrauterine contraceptive devices. Detectable HCG was not found in any subject, but in four subjects delayed LH pulses resulted in apparent low levels of HCG because of cross-reactivity in the HCG beta subunit radioimmunoassay.
对24名佩戴宫内节育器的受试者进行了人绒毛膜促性腺激素（HCG）β亚基、促黄体生成素（LH）和孕酮的每日测量。在任何受试者中均未检测到可检测到的HCG，但在4名受试者中，由于HCGβ亚基放射免疫测定中的交叉反应性，LH脉冲延迟导致了明显的低水平HCG。
