LDH -Lactate Dehydrogenase (Total and Isoenzymes)

Clinical definition of the LDH-Lactate Dehydrogenase test
Lactate dehydrogenase (LDH) is an enzyme found in the cells of almost all the body tissues especially the heart, kidney, liver, skeletal muscle, brain, blood cells, and lungs. It plays an important role in cellular respiration. It catalyzes the conversion of glucose (sugar) from food to pyruvate, which is the usable energy for our cells. When cells die, they release their LDH into the blood. Although LDH is abundantly present 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. Increased LDH in the blood could be due to liver disease, heart attack, anemia, muscle trauma, bone fractures, cancers, and/or infections such as meningitis, encephalitis, and HIV.

Why is the LDH-Lactate Dehydrogenase test done?
The lactate dehydrogenase (LDH) test measures the amount of LDH in the blood. Even though an LDH test is useful in diagnosing tissue damage, it is necessary to pinpoint the location of the damage and the severity of the condition. For this reason the LDH isoenzymes test mat be employed. There are five kinds of LDH isoenzymes which are found in specific concentrations in different organs and tissues of the body. By measuring levels of these isoenzymes in the blood, there would be a better idea of the type, location, and severity of the cellular damage. The different iso-enzymes are as follows:-

  • LDH-1: Heart, Red cells, Kidney
  • LDH-2: Heart, Red cells, Kidneys, but lesser than LDH 1
  • LDH-3: Lungs and other tissues
  • LDH-4: White cells, lymph nodes, muscles, liver cells
  • LDH-5: Liver and skeletal muscles

What are the common signs/symptoms when the LDH-Lactate Dehydrogenase test is done?

  • Swelling, bruising or redness, or open cuts as a consequence of the injury 
  • Pain at rest 
  • Pain when the specific muscle or the joint in relation to that muscle is used 
  • Weakness of the muscle or tendons
  • Inability to use the muscle at all

Who should do the LDH-Lactate Dehydrogenase test (Target population)?
Persons exhibiting signs or symptoms of having cellular or tissue damage.

What should I do before the LDH test?

Specimen type

Specimen collection procedure

Preparatory instructions before the test *

Serum (Blood Sample)

Venipuncture - Collection of blood from a vein, usually from the arm.

No Fasting Required.

No other special preparations required.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my LDH-Lactate Dehydrogenase test results?

Reference Range*


100- 190 IU/L **


**International units per liter
Inference- LDH enzymes may also rise in case of a cardio-vascular accident or cancers.
‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the LDH-Lactate Dehydrogenase test

  • Higher-than-normal levels may indicate:
  • Blood flow deficiency (ischemia)
  • Cerebrovascular accident (such as a stroke)
  • Heart attack
  • Hemolytic anemia
  • Infectious mononucleosis
  • Liver disease (for example, hepatitis)
  • Low blood pressure
  • Muscle injury
  • Muscular dystrophy
  • New abnormal tissue formation (usually cancer)
  • Pancreatitis
  • Tissue death

Other tests related to the LDH-Lactate Dehydrogenase test

  • CPK (Creatine Phopho Kinase)
  • CK-BB
  • CK-MB
  • CK-MM
  • Hemolytic anemia
  • Troponin
  • Myoglobin
  • Liver Panel
  • CSF Analysis
  • Body Fluid Analysis
  • Tumor Markers

Book This Test
LDH (Lactate Dehydrogenase)