What is a lactate dehydrogenase (LDH) test?

This test measures the level of lactate dehydrogenase (LDH), also known as lactic acid dehydrogenase, in your blood or sometimes in other body fluids. LDH is a type of protein, known as an enzyme. LDH plays an important role in making your body's energy. It is found in almost all the body's tissues, including those in the blood, heart, kidneys, brain, and lungs.

When these tissues are damaged, they release LDH into the bloodstream or other body fluids. If your LDH blood or fluid levels are high, it may mean certain tissues in your body have been damaged by disease or injury.

Other names: LD test, lactic dehydrogenase, lactic acid dehydrogenase

What is it used for?
An LDH test is most often used to:

Find out if you have tissue damage
Monitor disorders that cause tissue damage. These include anemia, liver disease, lung disease, and some types of infections.
Monitor chemotherapy for certain types cancer. The test may show if treatment is working.
Why do I need an LDH test?
You may need this test if other tests and/or your symptoms indicate you have tissue damage or disease. Symptoms will vary depending on the type of tissue damage you have.

You may also need an LDH test if you are currently being treated for cancer.

What do the results mean?

Higher than normal LDH levels usually means you have some type of tissue damage or disease. Disorders that cause high LDH levels include:

Anemia
Kidney disease
Liver disease
Muscle injury
Heart attack
Pancreatitis
Infections, including meningitis, encephalitis, and infectious mononucleosis (mono)
Certain types of cancer, including lymphoma and leukemia. A higher than normal LDH level may also mean treatment for cancer is not working.
Although the test can show if you have tissue damage or disease, it does not show where the damage is located. If your results showed higher than normal LDH levels, your provider may need to order more tests to make a diagnosis. One of these tests may be an LDH isoenzyme test. An LDH isoenzyme test measures different forms of LDH. It can help your provider find out about the location, type, and severity of tissue damage.