LH deficiency during COS

The lecture by Robert Fischer answers why a relative deficiency of luteinizing hormone develops in a subset of patients during controlled ovarian stimulation, and in which clinical situations it is worth restoring it with recombinant LH. He frames LH deficiency not as a rare exception but as a predictable consequence of modern pituitary-suppression protocols.

The starting point is the two-cell, two-gonadotropin model of folliculogenesis. LH acts on theca cells to drive androgen synthesis, and these androgens are aromatized into estrogens in granulosa cells under the influence of FSH. Without sufficient LH activity this substrate pathway weakens, and follicular maturation suffers even when the FSH dose is adequate.

Against the background of pituitary desensitization with GnRH agonists and antagonists, endogenous LH in some patients falls below the threshold required for full steroidogenesis. This iatrogenic deficiency matters most in women with intrinsically low LH activity, in older patients, and when the response to FSH-only stimulation is suboptimal or slow.

Fischer builds the rationale for adding LH around a 2017 meta-analysis that pooled data on the combined use of FSH and recombinant LH. Without citing individual numerical results, he lays out the logic of the evidence: in defined subgroups, restoring LH is associated with a more favorable cycle course and helps correct an inadequate response.

He also examines the choice of endpoint used to judge the benefit of the intervention. The number of retrieved oocytes is treated as a practical and reproducible marker of the stimulation outcome, although the author stresses the need to weigh it against oocyte maturity, embryo quality and, ultimately, the pregnancy rate.

The practical section addresses the clinical scenarios in which adding recombinant LH is most justified: hypogonadotropic states, patients of advanced reproductive age, an unexpectedly weak response in a previous cycle, and signs of slow follicular growth on monitoring. Fischer offers reference points for the decision rather than a rigid universal algorithm.