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Alternative names
Luteinizing hormone response to gonadotropin-releasing hormoneDefinition Return to top
LH response to GnRH is a test of the ability of the pituitary gland to appropriately respond to stimulation by a gonadotropin releasing hormone (GnRH, a hormone produced in the hypothalamus). This ability is assessed indirectly.How the test is performed Return to top
A blood sample is drawn prior to an injection of GnRH. After a specified time, other blood samples are drawn so that LH can be measured in the serum.
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test Return to top
Adults:How the test will feel Return to top
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.Why the test is performed Return to top
This test is used in to help differentiate primary (testicular or ovarian) from secondary (hypothalamic or pituitary) hypogonadism. This test may be performed as part of the evaluation of gonadal failure associated with low testosterone levels in men or low estradiol levels in women.Normal Values Return to top
Normal LH levels are:Note: IU/ml = international units per milliliter.
What abnormal results mean Return to top
What the risks are Return to top
Special considerations Return to top
GnRH (also called luteinizing hormone-releasing hormone, LHRH, or gonadotropin releasing hormone) is a peptide hormone secreted from the hypothalamus. GnRH stimulates the synthesis and release of LH (luteinizing hormone) and FSH (follicle-stimulating hormone). After puberty the secretion of GnRH, and also of LH and FSH, becomes pulsatile (rhythmic). However, continuous infusion of GnRH results in the inhibition of LH and FSH release.
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Page last updated: 28 October 2004 |