What is the Origin of HPG Axis Shutdown?

The HPG axis itself describes the anatomical and functional connection between the Hypothalamus, Pituitary gland, and Gonads (testes or ovaries). The concept of "shutdown" is a clinical term derived from the negative feedback loop inherent to this axis, where high levels of circulating hormones signal the central glands to cease production.

What is the Mechanism of HPG Axis Shutdown?

When high concentrations of exogenous sex hormones are introduced, they bind to receptors in the hypothalamus and pituitary, mimicking the natural negative feedback signal. This signal inhibits the pulsatile release of Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus and, consequently, Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) from the pituitary. The resulting lack of LH/FSH stimulation to the gonads causes testicular or ovarian atrophy and the cessation of natural hormone production, effectively shutting down the axis.

HPG Axis Shutdown

Meaning

A clinical state characterized by the suppression or complete cessation of the Hypothalamic-Pituitary-Gonadal (HPG) axis, the crucial endocrine system that regulates reproductive and sexual function. This shutdown results in a dramatic reduction in the production of endogenous gonadal hormones, such as testosterone and estrogen, due to inhibited signaling from the hypothalamus and pituitary glands. It is often an iatrogenic consequence of exogenous sex hormone administration or can occur due to severe stress or chronic illness.

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∞ HPG Axis Shutdown
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