Insulin-like growth factor (IGF)-I and IGF binding protein-3 concentrations in fluid from human stimulated follicles

Insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP- 3)play an important role in regulating follicle growth and maturation. Wehave evaluated whether responsiveness to gonadotrophins during an in- vitrofertilization (IVF) treatment is related to follicular fluid IGF- I andIGFBP-3 concentrations. We also investigated if a difference is present inIGF-I and IGFBP-3 concentrations between patients treated with humanmenopausal gonadotrophin (HMG) and patients treated with highly purifiedfollicle stimulating hormone (FSH). We have measured IGF-I and IGFBP-3 infollicular fluid from pre-ovulatory follicles in an IVF programme. All 70patients were stimulated after being down- regulated with agonadotrophin-releasing hormone (GnRH) analogue. IGF-I concentrations infollicular fluid were significantly inversely correlated with the number ofampoules FSH administered and number of days of FSH administration, andsignificantly correlated with the number of follicles aspirated. IGFBP-3concentrations were not correlated with any other parameter measured norwere IGF-I and IGFBP-3 concentrations correlated. IGFBP-3 concentrationswere significantly higher in patients receiving highly purified FSHcompared with patients receiving HMG (P < 0.005). These results are newevidence that IGF-I concentration in follicular fluid is higher in womenwho respond better to follicular stimulation, i.e. women who grow manyfollicles, women who need a shorter duration of stimulation and women whoneed fewer ampoules FSH before oocyte retrieval.