Bioactive FSH May Have Value as a Marker for Ovarian Reserve in Patients With Elevated Serum FSH and Normal Basal Antral Follicle Counts

Abstract

ObjectiveTo evaluate the bioactivity of FSH in women with paradoxically high serum immunoactive basal FSH levels and otherwise “normal” ovarian reserve as determined by ultrasound screening and response to gonadotropin stimulation.DesignCase Series at a large academic reproductive center.Materials and methodsWe compared immunoactive basal FSH levels (immulite assay (DPC)) and bioactive FSH levels in CHO cells transfected with the FSH receptor in two groups of women. Group 1 consisted of two patients with an elevated basal serum immunoactive FSH (> 13 mIU/mL), a normal basal antral follicle count (bAFC >8), and a robust response to gonadotropin stimulation (> 10 follicles) during IVF-ET therapy. Group 2 consisted of five patients with elevated basal serum FSH levels and either abnormal bAFC (< 6 total in both ovaries) or poor response to gonadotropin stimulation (< 5 mature follicles).ResultsTabled 1Tabled 1ConclusionsFSH with disproportionately lower bioactivity compared with immunoactivity on assay testing may account for some paradoxically abnormal basal FSH assessments in women with otherwise normal ovarian reserve and response to fertility therapy. Patients with normal antral follicle counts and elevated serum FSH by immunoassays can be candidates for a trial of IVF-ET, and based on our small series, can anticipate a reasonable reproductive outcome. Larger trials are required to assess if a basal bioactive FSH assessment can prospectively predict which of these patients are good IVF-ET candidates, and what cutoff (if any) of FSH bioactivity is most appropriate to use clinically. Presented with an abnormal FSH, but a normal bAFC, bioactivity testing may reassure that ovarian reserve is intact. ObjectiveTo evaluate the bioactivity of FSH in women with paradoxically high serum immunoactive basal FSH levels and otherwise “normal” ovarian reserve as determined by ultrasound screening and response to gonadotropin stimulation. To evaluate the bioactivity of FSH in women with paradoxically high serum immunoactive basal FSH levels and otherwise “normal” ovarian reserve as determined by ultrasound screening and response to gonadotropin stimulation. DesignCase Series at a large academic reproductive center. Case Series at a large academic reproductive center. Materials and methodsWe compared immunoactive basal FSH levels (immulite assay (DPC)) and bioactive FSH levels in CHO cells transfected with the FSH receptor in two groups of women. Group 1 consisted of two patients with an elevated basal serum immunoactive FSH (> 13 mIU/mL), a normal basal antral follicle count (bAFC >8), and a robust response to gonadotropin stimulation (> 10 follicles) during IVF-ET therapy. Group 2 consisted of five patients with elevated basal serum FSH levels and either abnormal bAFC (< 6 total in both ovaries) or poor response to gonadotropin stimulation (< 5 mature follicles). We compared immunoactive basal FSH levels (immulite assay (DPC)) and bioactive FSH levels in CHO cells transfected with the FSH receptor in two groups of women. Group 1 consisted of two patients with an elevated basal serum immunoactive FSH (> 13 mIU/mL), a normal basal antral follicle count (bAFC >8), and a robust response to gonadotropin stimulation (> 10 follicles) during IVF-ET therapy. Group 2 consisted of five patients with elevated basal serum FSH levels and either abnormal bAFC (< 6 total in both ovaries) or poor response to gonadotropin stimulation (< 5 mature follicles). ResultsTabled 1Tabled 1 ConclusionsFSH with disproportionately lower bioactivity compared with immunoactivity on assay testing may account for some paradoxically abnormal basal FSH assessments in women with otherwise normal ovarian reserve and response to fertility therapy. Patients with normal antral follicle counts and elevated serum FSH by immunoassays can be candidates for a trial of IVF-ET, and based on our small series, can anticipate a reasonable reproductive outcome. Larger trials are required to assess if a basal bioactive FSH assessment can prospectively predict which of these patients are good IVF-ET candidates, and what cutoff (if any) of FSH bioactivity is most appropriate to use clinically. Presented with an abnormal FSH, but a normal bAFC, bioactivity testing may reassure that ovarian reserve is intact. FSH with disproportionately lower bioactivity compared with immunoactivity on assay testing may account for some paradoxically abnormal basal FSH assessments in women with otherwise normal ovarian reserve and response to fertility therapy. Patients with normal antral follicle counts and elevated serum FSH by immunoassays can be candidates for a trial of IVF-ET, and based on our small series, can anticipate a reasonable reproductive outcome. Larger trials are required to assess if a basal bioactive FSH assessment can prospectively predict which of these patients are good IVF-ET candidates, and what cutoff (if any) of FSH bioactivity is most appropriate to use clinically. Presented with an abnormal FSH, but a normal bAFC, bioactivity testing may reassure that ovarian reserve is intact.