| Subject | Contents |
| Definition | A blood test which measures the amount of luteinizing hormone (LH). |
| Alternative Names | ICSH; Luteinizing hormone |
| How the test is performed | Adult or child: Blood is drawn from a vein ( venipuncture ), 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 distend (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. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. |
| How to prepare for the test | The health care provider may advise you to avoid drugs that may affect the test (see special considerations). For women in their reproductive years, the test may need to be done on a specific day of the menstrual cycle. 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: infant test or procedure preparation (birth to 1 year) toddler test or procedure preparation (1 to 3 years) preschooler test or procedure preparation (3 to 6 years) schoolage test or procedure preparation (6 to 12 years) adolescent test or procedure preparation (12 to 18 years) |
| How the test will feel | 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 | This test may be performed when a disorder associated with abnormal levels of LH is suspected. LH is a protein hormone secreted by the anterior pituitary gland. In women, an LH surge at mid-cycle causes ovulation. For the next week or so, LH maintains the corpus luteum which synthesizes progesterone. If a woman does not become pregnant the corpus luteum disintegrates after about 10 days. In men, LH stimulates production of testosterone by the Leydig cells of the testes . |
| Normal Values | normal adult male: 7 to 24 IU/L normal adult female: 5 to 20 IU/L, with the midcycle peak about 3 times the base level Note: IU/L = international units per liter |
| What abnormal results mean | Greater-than-normal levels of LH may indicate:anorchia (lack of, or nonfunctioning, testes )hypogonadismKlinefelter's syndromemenopause ovarian failure (see Ovarian hypofunction )polycystic ovary diseaseprecocious pubertyTurner's syndrome Lower-than-normal levels of LH may indicate hypopituitarism Additional conditions under which the test may be performed: anovulatory bleedinginfertilitymultiple endocrine neoplasia (MEN) Iovarian cysts |
| What the risks are | excessive bleedingfainting or feeling lightheaded hematoma (blood accumulating under the skin) infection (a slight risk any time the skin is broken) multiple punctures to locate veins |
| Special considerations | Recent exposure to radioisotope (a recent nuclear medicine scan, for example) can interfere with test results. Drugs that can decrease LH measurements include the birth control pill and hormone replacement therapy (estrogens, progesterone -- Progestins-oral) and testosterone . 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. |
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