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Alternative namesLD; Lactic (lactate) dehydrogenase isoenzymes
DefinitionThis is a test that measures the amount of the isoenzymes (different forms) of lactate dehydrogenase (LDH) in blood serum.
How the test is performed
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. An elastic band or blood pressure cuff is placed around the upper arm to cause veins to swell with blood.
A needle is inserted into a vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band 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.
How to prepare for the testThe health care provider may advise you to withhold drugs that may affect the test. (See special considerations.)
For infants and children:
The preparation involved in readying a child for any test or procedure depends on the 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 may feel moderate pain, while others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is usually performed when elevated LDH levels are suspected. Measurement of LDH isoenzymes helps determine the location of tissue damage.
What abnormal results meanBecause LDH can be found in many tissues in the body, total LDH is not specific for heart disease. Normally, the concentration of LDH-2 is greater than LDH-1. However, after a heart attack, the concentration of LDH-1 is generally higher than that of LDH-2. (This is called a "flipped" LDH pattern.) The LDH level rises within 24 to 72 hours after a heart attack, peaks in 3 to 4 days, and returns to normal in about 14 days.
Greater-than-normal LDH isoenzyme levels may be seen in:
What the risks are
Special considerationsDrugs that can increase LDH measurements include anesthetics, aspirin, clofibrate, fluorides, mithramycin, narcotics, and procainamide.
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: 5/12/2003Bridget Martell, M.D., Department of Internal Medicine, Albert Einstein College of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT