Please be patient! It may take up to ONE minute to load all the Engines.
Problems? Please contact our support.
LH response to GnRH
Alternative namesLH 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
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.
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:
How to prepare for the testAdults:
No special preparation is necessary.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the test will feelWhen 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 performedThis 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 ValuesNormal LH levels are:
Note: IU/ml = international units per milliliter.
What abnormal results mean
What the risks are
Special considerationsGnRH (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.
In women, estrogen levels increase during the menstrual cycle until a level is reached at which a positive feedback signal stimulates GnRH and LH release -- a phenomenon that is responsible for the LH surge prior to ovulation. Progesterone in high concentrations (for example, during the luteal phase of the menstrual cycle or during pregnancy) decreases the frequency of GnRH pulsations and also the response of the pituitary to GnRH. In men, testosterone decreases the frequency of LH pulses, probably by a direct effect on GnRH release. Inhibin, a peptide 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.
Update Date: 10/18/2003Francisco L. Gaudier, M. D., Maternal Fetal Medicine, Jacksonville, FL. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT