What causes the high levels of FSH and LH in central precocious puberty?

In central precocious puberty, the activation of the hypothalamic-pituitary-gonadal (HPG) axis leads to elevated levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This is primarily driven by the pulsatile release of gonadotropin-releasing hormone (GnRH) from the hypothalamus. As GnRH is released in a pulsatile manner, it stimulates the anterior pituitary gland to secrete FSH and LH, which in turn trigger the gonads to produce sex steroids such as estrogen and testosterone.

The key factor in central precocious puberty is this early activation of the HPG axis due to various potential causes, including idiopathic reasons or central nervous system abnormalities (such as tumors or lesions). The increased levels of FSH and LH result from this early stimulation of the gonads, leading to the development of secondary sexual characteristics at an unusually young age.

In contrast, other conditions such as adrenal gland hyperplasia or gonadal tumors might also lead to increased sex steroids, but they typically result in different hormonal profiles and mechanisms that do not involve increased FSH and LH to the same extent as a direct activation of GnRH does in central precocious puberty.