Serum FSH levels in women with polycystic ovary syndrome during ovulation induction using down-regulation and urofollitropin

Objective: To evaluate retrospectively the use of serum FSH levels and to correlate them with follicular growth in a clinical ovulation induction program. Methods: Twenty women with infertility due to anovulation associated with polycystic ovary syndrome (PCOS) were studied. The patients were down-regulated with a long GnRH agonist protocol and stimulated with purified urofollitropin, using a low-dose step-up regimen, Repeated serum samples were drawn and transvaginal ultrasound scans were performed. During the exogenous FSH therapy serum FSH levels resulting in continuous follicular growth were analyzed, as well as the rates of ovulation, pregnancy, cancellation and conversion to in vitro fertilization (TVF). Results: Thirty-two out of fifty treatment cycles led to ovulation, resulting in five term pregnancies. Eight cycles were converted to IVF/embryo transfer due to multiple follicular growth. They resulted in two pregnancies. Ten cycles were cancelled because of impaired follicular growth. The serum FSH levels (median 6 IU/l) resulting in continuous growth of the follicles were relatively stable within patients (variation 15%) but varied considerably between patients (45%), The relationship between FSH dose and serum level was different for lean and obese PCOS patients after subcutaneously injected urofollitropin. Conclusions: There seems to be a difference in resorption/metabolism between lean and obese PCOS patients with regard to s.c. injected FSH. The intra-patient coefficient of variation (C.V.) of the serum FSH response level was quite low as was the C.V. of the FSH dose at the response level. This allowed a more rapid dose adjustment in subsequent cycles. Analysis of serum FSH during induction of ovulation with gonadotropins seems to be of limited value in clinical programs.