Lactate Dehydrogenase (LDH) Isoenzymes Test
Reviewed
Also called: LD isoenzymes, lactic dehydrogenase isoenzyme, LDH fractionation
This test measures lactate dehydrogenase (LDH) isoenzymes in a sample of your blood.
Specimen: blood
Why this test may be ordered
- You have symptoms that suggest you have some type of tissue damage.
- You had a total LDH test that showed you have higher than normal levels of LDH.
- You have a condition that affects LDH levels, and your provider wants to learn more about your condition or find out if your treatment is helping.
Preparation and collection
You don't need any special preparations for an LDH isoenzymes test.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
The meaning of your LDH isoenzyme test results depends on the reason you had the test, your symptoms, and the results of other tests you've had. In general, a high level of one or more LDH isoenzymes usually means you have some type of tissue damage.
- LDH-1 higher than LDH-2: LDH-1 that's higher than LDH-2 may be a sign of a certain type of anemia. Limitation: It's also possible to have high LDH isoenzymes if many red blood cells broke open when your sample was collected and tested. Next step: Ask your provider to explain what your results say about your health.
- LDH-5 higher than LDH-4: LDH-5 that's higher than LDH-4 may be a sign of liver damage or disease. Limitation: High levels of certain LDH isoenzymes can be caused by intense exercise and certain medicines, including aspirin. Next step: If you have questions about your results, talk with your provider.
- High levels of two or more isoenzymes: High levels of two or more isoenzymes may mean you have two different conditions. Or it could be a sign of cancer that has spread to different tissues. Limitation: Higher than normal LDH isoenzyme levels don't always mean you have a medical condition that needs treatment. Next step: Ask your provider to explain what your results say about your health.
- Low LDH isoenzyme levels: Lower than normal LDH isoenzyme levels aren't common and usually aren't considered to be a health problem. Limitation: Your levels of certain isoenzymes may be affected by taking large amounts of vitamin C or vitamin E. Next step: If you have questions about your results, talk with your provider.
- An LDH isoenzymes test alone cannot diagnose what is causing the damage.
- Because each LDH isoenzyme is found in more than one type of tissue, other more specific tests are often used with or instead of an LDH isoenzymes test to more accurately identify which tissue is damaged.
- High LDH isoenzyme levels do not always mean you have a medical condition that needs treatment; they can be caused by intense exercise, certain medicines (e.g., aspirin), or red blood cells breaking open during sample collection.
- Lower than normal LDH isoenzyme levels are not common and usually are not considered to be a health problem; they may be affected by taking large amounts of vitamin C or vitamin E, or rarely by a genetic disorder.
What to do next
Ask your provider to explain what your results say about your health. If you have questions about your results, talk with your provider.
- Why do I need this test?
- What do my results mean about my health?
- Are there other tests I should have?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Lactate Dehydrogenase (LDH) Isoenzymes Test