Decline in insulin-like growth factor I levels after clomiphene citrate does not correct hyperandrogenemia in polycystic ovary syndrome

Abstract

It is widely accepted that the action of clomiphene citrate (CC) is mediated through its antiestrogenic properties on the hypothalamic-pituitary axis. Although insulin-like growth factor I (IGF-I) enhances the thecal cell response to LH, and estrogen treatment is associated with a reduction in IGF- I levels, CC is known to decrease circulatory IGF-I levels in polycystic ovary syndrome (PCOS) patients. The impact of lowering IGF-I levels on androgen levels in PCOS is unknown. This study was designed to examine the impact of CC treatment on the interrelationships of IGF-I, androgens, and estrogens in normal subjects and patients with PCOS. IGF-I, gonadotropin, androgen, estrogen, and sex hormone-binding globulin levels were measured in 8 PCOS patients and 10 normal subjects before and after treatment with the antiestrogen CC. Studies were performed in the early follicular phase, days 4-6 of the menstrual cycle in normal subjects. In normal subjects, CC treatment led to a significant increase in estradiol (84 ± 10 to 234 ± 62 pmol/L, untreated and CC treated; P < 0.05) and estrone (125 ± 14 to 257 ± 29 pmol/L; P < 0.05) levels with a significant lowering of IGF-I levels (297 ± 25 to 230 ± 17 μg/L; P < 0.05). Similarly, in PCOS patients a significant increase in estradiol (110 ± 11 to 245 ± 58 pmol/L; P < 0.05) and estrone (301 ± 32 to 401 ± 90 pmol/L; P < 0.05) levels and a significant lowering of IGF-I levels (330 ± 43 to 214 ± 27 μg/L; P < 0.05) were observed after CC treatment. However, no significant correlation was observed between changes in IGF-I and changes in estradiol in either group. Compared to pretreatment levels, no significant changes in the following parameters were observed after 5 days of CC treatment in either study group: testosterone, testosterone/sex hormone-binding globulin ratio, and androstenedione. The relationship among CC treatment, gonadotropin, estrogen, and IGF-I levels is complex. Changes in blood IGF-I levels are not associated with changes in androgen levels, although paracrine and or autocrine effects cannot be excluded.