LDH, also called lactic dehydrogenase or lactate dehydrogenase, is an enzyme present within cells responsible for the metabolism of glucose in the body. This enzyme can be found in various organs and tissues and, therefore, its elevation is not specific, and other tests are recommended to reach a diagnosis.
If there is an altered LDH result, in addition to other tests, the doctor may indicate the dosage of LDH isoenzymes, the elevation of which may indicate more specific changes:
- LDH-1, which is present in the heart, red blood cells and kidneys; LDH-2, which can be found in the heart, in a smaller amount, and in leukocytes; LDH-3, which is present in the lungs; LDH-4, which is found in the placenta and pancreas; LDH-5, which is found in the liver and skeletal muscle.
The normal values of lactate dehydrogenase can vary according to the laboratory, being normally considered between 120 and 246 IU / L in adults.
What is the exam for
The LDH test can be ordered by the doctor as a routine test, along with other laboratory tests. However, this test is mainly indicated in case of investigation of cardiac problems, being requested together with Creatinophosphokinase (CK) and troponin, or of hepatic alterations, being also requested the dosage of TGO / AST (Oxalacetic Transaminase / Aspartate Aminotransferase), TGP / ALT (Glutamic Pyruvic Transaminase / Alanine Aminotransferase) and GGT (gamma glutamyl transferase). Get to know other tests that evaluate the liver.
In order to take the exam most of the time it is not necessary to fast or any other type of preparation, however some laboratories indicate that it is necessary that the person is at least 4 hours fast. Therefore, before conducting the exam, it is important to inform the laboratory of the appropriate procedure, in addition to informing the use of medications.
What does high LDH mean
The increase in LDH is usually indicative of damage to organs or tissues. This is because as a consequence of cellular damage, the LDH contained within the cells is released and circulates in the bloodstream, and its concentration is assessed by means of a blood test. The main situations in which the increase in LDH can be seen are:
- Megaloblastic anemia; Carcinoma; Septic shock; Infarction; Hemolytic anemia; Leukemia; Mononucleosis; Hepatitis; Obstructive jaundice; Cirrhosis.
Some situations can increase LDH levels, not being indicative of disease, especially if other requested laboratory parameters are normal. Some of the conditions that can alter LDH levels in the blood are intense physical activity, use of some medications and pregnancy.
What can be low LDH?
The decrease in the amount of lactic dehydrogenase in the blood is not normally a cause for concern and is not related to disease and is not a reason for investigation. In some cases, the decrease in LDH may be related to the excess of vitamin C, and changes in the person's eating habits may be recommended.
