lactate_dehydrogenase_ldh_test
Reviewed
Also called: LD test, lactic dehydrogenase, lactic acid dehydrogenase
This test measures the level of lactate dehydrogenase (LDH), an enzyme found in many body tissues. When cells are damaged by disease or injury, LDH is released into the blood or other fluids. The test helps detect tissue damage but cannot identify the exact location or cause; it is usually done with other tests.
Specimen: blood (or other body fluids such as cerebrospinal fluid, peritoneal fluid, pleural fluid)
Why this test may be ordered
- To help diagnose or monitor conditions affecting the blood, liver, lungs, kidneys, heart, pancreas, brain, or spinal cord
- To monitor chronic conditions such as muscular dystrophy or HIV
- To help diagnose certain severe infections
- To assess the severity of certain cancers (e.g., multiple myeloma, lymphoma, leukemia, testicular cancer, melanoma)
- To check whether cancer treatment is working
Preparation and collection
No special preparation is needed for a blood sample. For other fluid samples, follow your provider's instructions.
A blood sample is taken from a vein in your arm. If other body fluids are needed, procedures such as lumbar puncture (spinal tap), thoracentesis, or paracentesis may be used.
There is very little risk to having a blood test. You may have slight pain or bruising at the needle site, but most symptoms go away quickly. For other fluid collection procedures, your provider will explain the risks.
Understanding results
Your LDH test results depend on the reason for the test, your symptoms, and other test results. Ask your provider to explain what your results mean for your health.
- Higher than normal LDH level: Usually indicates some type of tissue damage from disease, infection, or injury. However, high levels can also be caused by intense exercise, certain medicines (e.g., aspirin), or if red blood cells broke open during sample collection. More tests are often needed to diagnose the condition. Limitation: A high level does not always mean a medical condition requiring treatment. The test alone cannot show what is damaging the tissues or where the damage is located. Next step: Your provider may order more tests, such as an LDH isoenzyme test, to help identify the type and location of tissue damage.
- Lower than normal LDH level: Not common and usually not considered a health problem. May be caused by taking large amounts of vitamin C or vitamin E, or by a rare genetic disorder called lactate dehydrogenase deficiency. Limitation: Low levels are rarely a concern, but your provider can help interpret them in your specific situation. Next step: Your provider will discuss whether any follow-up is needed based on your overall health and other test results.
- An LDH test alone cannot show what is damaging your tissues or where the damage is located.
- High levels can be caused by intense exercise, certain medicines, or sample handling issues, not just disease.
- Low levels are uncommon and usually not a health problem.
What to do next
If your results are higher than normal, your provider may order an LDH isoenzyme test to help find out which tissues are damaged. Always discuss your results with your healthcare provider.
- Why do I need this test?
- What do my results mean for my health?
- Do I need any follow-up tests?
Evidence source
U.S. National Library of Medicine: lactate_dehydrogenase_ldh_test