LH response to GnRH

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Luteinizing hormone response to gonadotropin-releasing hormone

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

GnRH, which stands for gonadotropin releasing hormone, is secreted from the hypothalamus. It is also called luteinizing hormone-releasing hormone or LHRH.

GnRH stimulates the creation and release of LH (luteinizing hormone) and FSH (follicle-stimulating hormone). After puberty GnRH secretion, as well as LH and FSH secretion, becomes pulsatile (meaning rhythmic). Having a steady infusion of GnRH, however, causes inhibition (stopping the release of) LH and FSH.

In women, estrogen levels rise during the menstrual cycle until there is enough estrogen present to stimulate the release of GnRH and LH. This is the phenomenon that causes the LH surge prior to ovulation.

Progesterone in high concentrations (for example, during the luteal phase of the menstrual cycle or during pregnancy) reduces GnRH pulses and also reduces the response of the pituitary gland to GnRH.

In men, testosterone reduces LH pulses, probably by reducing the release of GnRH. Inhibin, a hormone produced by the testes and ovaries, is probably the major inhibitor of FSH release.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Review Date: 08/08/2005
Reviewed By: Sharon Roseanne Thompason, M.D., M.P.H., Clinical Fellow, Department of Obstetrics & Gynecology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.