A review of luteinising hormone and human chorionic gonadotropin when used in assisted reproductive technology

Abstract

Gonadotropins extracted from the urine of post-menopausal women have traditionally been used to stimulate folliculogenesis in the treatment of infertility and in assisted reproductive technology (ART). Products, such as human menopausal gonadotropin (hMG), consist not only of a mixture of the hormones, follicle-stimulating hormone (FSH), luteinising hormone (LH) and human chorionic gonadotropin (hCG), but also other biologically active contaminants, such as growth factors, binding proteins and prion proteins. The actual amount of molecular LH in hMG preparations varies considerably due to the purification process, thus hCG, mimicking LH action, is added to standardise the product. However, unlike LH, hCG plays a different role during the natural human menstrual cycle. It is secreted by the embryo and placenta, and its main role is to support implantation and pregnancy. More recently, recombinant gonadotropins (r-hFSH and r-hLH) have become available for ART therapies. Recombinant LH contains only LH molecules. In the field of reproduction there has been controversy in recent years over whether r-hLH or hCG should be used for ART. This review examines the existing evidence for molecular and functional differences between LH and hCG and assesses the clinical implications of hCG-supplemented urinary therapy compared with recombinant therapies used for ART.

Figure 1

Hormones act in concert to regulate normal ovarian function.

Figure 2

LH immunoassay concentrations over time after three routes of administration. Log-linear plot of LH immunoassay concentrations over time after Single IV (solid line), IM (long dashed line), and SC short dashed line administration of 10,000 IU of r-hLH (mean ± 1 SEM, 12 subjects). Reprinted from Fertil Steril, 69, le Cotonnec JY, Porchet HC, Beltrami V, Munafo A, Clinical pharmacology of recombinant human luteinizing hormone: Part II. Bioavailability of recombinant human luteinizing hormone assessed with an immunoassay and an in vitro bioassay, pages 195–200, Copyright 1998, with permission from Elsevier [20].