Clomiphene citrate reduces serum insulin-like growth factor I and increases sex hormone-binding globulin levels in women with polycystic ovary syndrome

Abstract

To evaluate the effect of clomiphene citrate (CC) on circulating levels of insulin-like growth factor I (IGF-I) and sex hormone-binding globulin (SHBG) in patients with polycystic ovary syndrome (PCOS). Prospective open trial. Eight women with clinical and biochemical evidence of PCOS. One hundred fifty milligrams CC was administered orally for 5 days. Serum IGF-I, SHBG, LH, FSH, and E2 levels were determined for 8 days, beginning 3 days before CC treatment. A progressive decline in serum IGF-I levels was observed in all subjects reaching a maximum of 30% on the 5th day of therapy (40.6 +/- 5.1 to 28.7 +/- 4.0 nmol/L [conversion factor to SI unit, 0.13]). This was correlated inversely with the expected rises in LH, FSH, and E2 levels. Concomitantly, there was a 23% rise in SHBG levels. The absolute decrease of IGF-I levels was negatively correlated with age and was independent of body mass index. These observations suggest that oral administration of CC has an impact on the IGF-I and SHBG systems, which may be involved in the initiation of ovulatory function in PCOS.