An LDH (lactate dehydrogenase) test measures the level of LDH in your blood or other body fluid to check for tissue damage. Healthcare providers order LDH tests to help diagnose and monitor several different conditions.
Lactate dehydrogenase (LDH) is an important enzyme that helps with cellular respiration, the process through which your body transforms glucose (sugar) from the food you eat into energy for your cells.
Enzymes are proteins that help speed up metabolism, or the chemical reactions in your body. They build some substances and break others down.
As new cells form in tissues, your body gets rid of older or “dead” cells. This normal process causes your tissues to release LDH into your bloodstream or other body fluids. Because of this, it’s normal to have some LDH in a blood or fluid sample at all times.
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An LDH (lactate dehydrogenase) test measures the amount of LDH in your blood or other body fluid to check for tissue damage.
While it’s normal to have some LDH in your blood or body fluids, when tissues in your body experience damage or injury, they release excess LDH into your bloodstream or other body fluids. If your LDH blood or fluid levels are elevated, it may indicate that certain tissues in your body have been damaged by a chronic (long-term) or acute (short-term) disease or injury.
LDH tests can’t determine which tissues in your body are damaged. Because of this, healthcare providers often order other tests alongside LDH tests to help diagnose conditions.
Other names for an LDH test include:
Healthcare providers use an LDH test to help diagnose and monitor several different health conditions.
The most common uses for an LDH test include:
Since providers order LDH tests in a wide variety of situations, you may want to ask your provider what the purpose of LDH testing is for you.
A healthcare provider called a phlebotomist usually performs blood draws, including those for an LDH blood test, but any healthcare provider who is trained in drawing blood can perform this task. The provider then sends the sample to a lab where a medical laboratory scientist prepares the samples and performs the test on machines known as analyzers.
Healthcare providers sometimes need to measure LDH in other body fluids, including fluids in your spinal cord, lungs or abdomen (belly). If this is the case, a specially trained provider will perform the test.
You don’t need to do anything special to prepare for an LDH blood test.
You may need special preparation for an LDH test that requires a sample from other bodily fluids. In this case, your healthcare provider will let you know what you need to do.
You can expect to experience the following during a blood test, or blood draw:
The entire procedure usually takes less than five minutes.
Healthcare providers sometimes need to measure LDH in other body fluids, including fluids in your:
If you’re having one of these tests, your healthcare provider will provide information about the procedure and what you can expect.
After a healthcare provider has collected your blood or another bodily fluid sample, they’ll send it to a laboratory for testing. Once the test results are back, your healthcare provider will share the results with you.
Blood tests are a very common and essential part of medical testing and screening. There’s very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.
In most cases, you should have your LDH test results within one to two days, though it could take longer.
If you’ve gotten an LDH test at the hospital or at an emergency room, your healthcare provider will likely get the results within hours.
Blood test reports, including LDH blood test reports, usually provide the following information:
Laboratories may have different reference ranges for normal LDH levels. When you get your blood test results back, there’ll be information that indicates what that lab’s normal blood LDH range is.
In general, the normal ranges for an LDH (lactate dehydrogenase) blood test include:
Children typically have higher normal levels of LDH than adults.
If you have any questions about your results, be sure to ask your healthcare provider.
Having higher-than-normal LDH levels usually means you have some type of tissue damage from an injury, disease or infection — whether chronic or acute.
Conditions that cause high LDH levels include:
A higher-than-normal LDH level may also mean that cancer treatment isn’t working.
Although an LDH test can show if you have tissue damage or disease, it can’t reveal where the damage is in your body. LDH can also be falsely elevated if your red blood cells break during the sample collection. If your results show elevated LDH levels, your healthcare provider may need to order more tests to make a diagnosis.
If your LDH test results reveal that you have high LDH levels, it doesn't necessarily mean that you have a medical condition.
A few factors can increase your LDH levels, including:
There could’ve also been an error in the sample collection, transportation and/or processing of the test.
When interpreting your results, your healthcare provider will consider several factors, including your current medications, medical history and symptoms. They’ll let you know if you need further testing.
If you have questions about your results, don’t be afraid to talk to your healthcare provider.
Having a lower-than-normal LDH test result is uncommon.
Lower-than-normal LDH levels may indicate a very rare genetic condition called lactate dehydrogenase A deficiency (glycogen storage disease XI) or lactate dehydrogenase B deficiency.
High vitamin C consumption can cause falsely low LDH test results.
If you’ve gotten an LDH test, it may be helpful to ask your provider the following questions:
A note from Cleveland Clinic
Seeing an abnormal test result can be stressful. Know that having a high level of LDH (lactate dehydrogenase) doesn’t necessarily mean you have a medical condition and need treatment. Your healthcare provider will let you know if you need to undergo further tests to determine the cause of the abnormal level. Don’t be afraid to ask your provider questions. They’re there to help you.
Last reviewed by a Cleveland Clinic medical professional on 04/15/2022.
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