Luteal-phase inhibin A and follicular-phase inhibin B levels are not characteristic of patients with an elevated LH-to-FSH ratio

Abstract

Purpose: To test whether serum inhibin levels are related to differences in gonadotropin concentrations between patients with an elevated LH-to-FSH ratio (ELF patients) and controls.Methods: 32 ELF patients were matched with controls by age, body mass index (BMI), and cycle length.Results: No statistically significant difference was found in follicular-phase inhibin B levels or midluteal inhibin A levels between cases and controls. Significant negative correlation was observed between follicular-phase inhibin B concentrations and BMI in ELF patients but not among controls. LH and FSH were positively related to inhibin B levels in ELF patients. Midluteal inhibin A correlated with sex hormone-binding globulin in controls but not in ELF patients.Conclusions: Neither follicular-phase inhibin B levels nor midluteal inhibin A levels are characteristic of patients with an elevated LH-to-FSH ratio. Opposite correlations with LH and BMI suggest dysregulation of inhibin secretion rather than dimeric inhibins having a central role to the endocrinological imbalance observed in polycystic ovary syndrome.

Anti-Müllerian Hormone and Inhibin-A, but not Inhibin-B or Insulin-Like Peptide-3, may be Used as Surrogates in the Diagnosis of Polycystic Ovary Syndrome in Adolescents: Preliminary Results

“…Some studies have shown that INH-B level increases in patients with PCOS (28), whereas others have shown that it decreases (30). Overall, results generally indicate that the INH-B level does not change markedly in PCOS patients (20,21,23,27,29). It has been shown that the levels of INH-A are low in the follicular phase of ovulation, increase just after ovulation, and increase further as the follicle develops (49,50).…”

“…Studies conducted with adults have yielded controversial results. While some have shown that INH-A does not change in patients with PCOS (20,21), other studies have shown an increase (22,23,24), while some other studies reported a decrease (25,26,27). Some studies have shown that INH-B level increases in patients with PCOS (28), whereas others have shown that it decreases (30).…”

“…It has been shown that the levels of INH-A are low in the follicular phase of ovulation, increase just after ovulation, and increase further as the follicle develops (49,50). INH-B is released from small antral cells during the follicular phase (19,21). It is to be expected that the level of INH-A, which is related to increased LH level, and the level of INH-B, which is related to increased FSH level, are variable in patients with PCOS since LH and FSH levels are also variable in these patients who mostly have an increased LH/FSH ratio with LH predominance.…”

“…It is to be expected that the level of INH-A, which is related to increased LH level, and the level of INH-B, which is related to increased FSH level, are variable in patients with PCOS since LH and FSH levels are also variable in these patients who mostly have an increased LH/FSH ratio with LH predominance. These studies have been conducted on women with PCOS according to menstrual cycle phases, considering the periods of the menstrual cycle (21). However, patients with PCOS generally have LH predominance.…”

“…However, conflicting results have been reported in studies conducted on adult women. Some studies have shown that INH-A does not change in patients with PCOS (20,21), whereas others have shown that it increases (22,23,24) or decreases (25,26,27). There are also similar controversial results related with INH-B levels (20,21,27,28,29,30).…”