LDH, also known as lactate dehydrogenase, is an enzyme that is found inside almost all of the body's tissues. These enzymes play a significant role in physiological processes such as cellular respiration - converting the food consumed into usable energy for the cells. Measuring the LDH is considered to be one of the best general indicators of the existence of any severe, acute or chronic tissue damage and is also measured to monitor certain progressive conditions. While an LDH test is generally very useful in identifying the presence of tissue damage, it will usually require the administration of some other medical test to pinpoint the location of the actual tissue damage. LDH blood tests are usually ordered when a doctor requires an overall screening to be performed to identify the presence of tissue damage. The test will usually be administered along with certain other tests such as an ALT, AST or ALP to help identify the exact organs that are involved.
As with any blood test, the test is performed by taking a sample of the patient's blood and analyzing it in a laboratory. The sample is collected by inserting a syringe into the patient's vein in the arm, just behind the elbow and extracting the required amount. The doctor or nurse may fasten a band over the upper part of the arm to temporarily prevent the blood from flowing and thereby causing the vein to bulge - making it easier to extract the sample. Once enough blood has been collected, a small cotton bandage will be pressed on top of the broken skin to prevent substantial blood loss and expedite clotting.
High LDH levels indicate the presence of a number of conditions such as hemolytic anemia, infectious mononucleosis, kidney disease, liver disease and pancreatitis amongst a host of other conditions. However, one should also be aware of the fact that high LDH levels are also usually the result of strenuous exercise. One should also be aware of the fact that hemolysis of the blood specimen could also potentially lead to falsely elevated results.
LDH blood tests require no specific preparation and the procedure is rather fast. In most cases, once the blood specimen has been attained, the doctor will ask you to return either in a few hours or days to get the results of the analysis. It is important to inform your doctor if you are taking any medication, prescribed or otherwise, as they may have a tendency to interfere with the test results.