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Blood Test: Lactate Dehydrogenase (LDH)

What It Is

Lactate dehydrogenase (also called lactic acid dehydrogenase, or LDH) is an enzyme found in almost all body tissues. It plays an important role in cellular respiration, the process by which glucose (sugar) from food is converted into usable energy for our cells.

Although LDH is abundant in tissue cells, blood levels of the enzyme are normally low. However, when tissues are damaged by injury or disease, they release more LDH into the bloodstream. Conditions that can cause increased LDH in the blood include liver disease, heart attack, anemia, muscle trauma, bone fractures, cancers, and infections such as meningitis, encephalitis, and HIV.

Even though an LDH test is useful in diagnosing tissue damage, other tests are usually necessary to pinpoint the location of the damage. One such test is called the LDH isoenzymes test. LDH isoenzymes are five kinds of the LDH enzyme that are found in specific concentrations in different organs and tissues. By measuring the blood levels of these isoenzymes, doctors can get a better idea of the type, location, and severity of the cellular damage.

Why It's Done

The LDH test is generally used to screen for tissue damage. This damage may be acute (as in the case of a traumatic injury) or chronic (due to a long-term condition such as liver disease or certain types of anemia). It also may be used to monitor progressive conditions, such as muscular dystrophy and HIV.



The Procedure





What to Expect


Getting the Results




  • fainting or feeling lightheaded
  • pain associated with multiple punctures to locate a vein

Helping Your Child



If You Have Questions

If you have questions about the LDH test, speak with your doctor.

Reviewed by: Yamini Durani, MD
Date reviewed: August 2014