IGF1 and precocious puberty: Meanwhile, the development of ICPP shows an intimate association with the levels of vitamin-D, sex hormones, insulin-like growth factor-1 (IGF-1), leptin, etc.9 Gonadotropin-releasing hormone (GnRH) stimulation test has been accepted to be the gold standard for diagnosing ICPP so far,10 which is also extensively employed to assist in the differential diagnosis of precocious puberty in children.