LDH isoenzyme blood test

LDH Isoenzyme Blood Test

The LDH isoenzyme blood test measures the level of lactic acid dehydrogenase (LDH) isoenzymes in the blood. It helps diagnose certain types of anemia, muscular diseases, and others. This test also may be done to monitor the progress of some types of cancer.


No preparation is usually necessary for this test. Your doctor may ask you to fast (not eat or drink) for a few hours before the test.


The blood sample is taken from a vein in your arm using a needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes only a few minutes.

Types of LDH Isoenzymes

There are five types of LDH isoenzymes. They are:

  • LDH-1
  • LDH-2
  • LDH-3
  • LDH-4
  • LDH-5


Getting a blood test with a needle carries some risks. These include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight sting or pain. Afterward, the site may be sore.

Why Get a LDH Isoenzyme Test?

Your doctor may order an LDH isoenzyme test if you have certain symptoms such as unexplained pain, difficulty in breathing, or anemia. The test can help diagnose certain types of disorders, such as:

  • Heart muscle damage
  • Lung damage
  • Liver disease
  • Cancer

When to Get Tested

Your doctor may recommend you get an LDH isoenzyme test when they suspect you have certain diseases. Your doctor may also recommend periodic follow-up tests to monitor the progress of a disease.