Primus Pathology Laboratory

Lactate Dehydrogenase Test

Last Updated on July 28, 2022 by Dr. Neeraj Gujar


LDH (lactate dehydrogenase), a test that measures LDH levels in the blood and other fluids, is used to detect tissue damage.

LDH is a normal part of your blood and body fluids. However, if tissues are damaged or injured, they may release more LDH into your bloodstream. Your LDH fluid or blood levels may be elevated if you have a chronic or acute disease or injury to certain tissues.

LDH tests cannot determine which tissues are damaged. To diagnose conditions, healthcare providers may order additional tests in addition to LDH tests.

An LDH test can also be called:

  • LD Test
  • Lactic dehydrogenase.
  • Lactic acid dehydrogenase.

What Is Lactate Dehydrogenase (LDH)?

Lactate Dehydrogenase is an important enzyme. It aids with cell respiration. This is the process by which your body converts sugar (glucose) from food into energy for your cells.

Enzymes are proteins that help accelerate metabolism or chemical reactions in the body. They can make some substances stronger and weaker than others.

LDH is found in nearly all tissues of your body. LDH is found in the muscles and liver. It also appears in your kidneys.

Your body eliminates “dead” or older cells as new cells are formed in tissues. Your tissues will naturally release LDH into your bloodstream and other body fluids as part of this normal process. It’s perfectly normal for LDH to be present in any fluid or blood sample.

What Are the Types of LDH Isoenzymes?

Five different forms of LDH are called isoenzymes. They are distinguished by slight differences in their structure. The isoenzymes of LDH are LDH-1, LDH-2, LDH-3, LDH-4, and LDH-5.

Different LDH isoenzymes are found in different body tissues. The areas of highest concentration for each type of isoenzyme are:

  • LDH-1: Heart and RBCs
  • LDH-2: Heart and RBCs
  • LDH-3: Lymph tissue, platelets, pancreas, lungs
  • LDH-4: Skeletal muscle and liver
  • LDH-5: Skeletal muscle and liver

Also Read: What’s the Purpose of Liver Function Test? What Diseases Does It Detect?

Why Test Is Done?

One might be ordered by your doctor for any of the following reasons:

  • To determine if you have any tissue damage, and if so, how severe.
  • For monitoring severe infections such as megaloblastic or hemolytic anemias, kidney disease, and liver disease.
  • To assist in the evaluation of certain types of cancers and to check your treatment.

LDH tests may be performed regularly depending on your health condition.

An LDH test for body fluids might be performed to:

  • Find out what is causing fluid buildup. This could be caused by injury or inflammation. It could also be caused by an imbalance of blood pressure and blood protein levels.
  • You can help determine whether you have bacterial meningitis or viral meningitis.

When Get Tested?

This test may be required if you have symptoms that indicate tissue disease or damage. The type of tissue damage that you have will affect the symptoms.

If you are currently being treated with cancer, an LDH test may be required.

How To Get Tested?

Patient getting blood test done

A phlebotomist is a healthcare provider that draws blood. However, any healthcare provider with training in drawing blood can do this job. The provider sends the sample to the lab, where a medical laboratory scientist prepares them and performs the test using machines called analyzers.

Sometimes, healthcare providers may need to test for LDH in other fluids such as fluids in the spinal cord or lungs. A specially trained provider will conduct the test if this is the case.

Before the Test

An LDH blood test does not require you to do anything extra. If the test requires any special preparations, your healthcare provider will tell you what to do in this situation.

During the Test

These are some of the things you might experience during a blood draw or test.

  • A healthcare provider will place you in a chair and examine your arms to see if there is a vein. This vein is located on the inside of your arm, usually to the side of your elbow.
  • Once they have located the vein, they will clean it and disinfect it.
  • The doctor will then insert a tiny needle into your vein to collect a sample of blood. It may feel like a tiny pinch.
  • A small amount of blood will be collected in a tube after the needle is inserted.
  • Once they have sufficient blood for testing, they will remove the needle from the site and place a gauze or cotton ball on the area to stop bleeding.
  • The bandage will be placed over the area and you’ll be done.

The whole process usually takes less than five minutes.

Sometimes, healthcare providers may need to measure LDH levels in other fluids.

  • Chest or lungs (pleural fluid)
  • Spinal cord (cerebrospinal fluid or CSF)
  • Abdomen (peritoneal fluid)

Your healthcare provider will inform you about these procedures and what to expect.

After The Test

Once your blood or other bodily fluid samples have been collected by a healthcare provider, they will be sent to a laboratory for testing. Your healthcare provider will share your results once the test results have been returned.

Blood tests are very safe. The site of your blood draw may cause slight tenderness or a bump, but these usually disappear quickly.

Test Results

LDH levels vary based on age and the individual laboratory. Infants and young children will have much higher normal LDH levels than older children or adults. LDH is often reported in units per liter (U/L). In general, normal ranges for LDH levels in the blood are as follows:

AgeNormal LDH level
0 to 10 days290–2000 U/L
10 days to 2 years180–430 U/L
2 to 12 years110–295 U/L
Older than 12 years100–190 U/L

Interpreting Results

High Levels of LDH

Lactate Dehydrogenase (LDH) levels above a certain level may indicate tissue damage. A high level of LDH may be indicative of multiple causes of tissue damage. LDH levels exceedingly high could be a sign of severe disease or multiple organ dysfunction.

LDH is found in many tissues throughout the body so a single measurement of LDH won’t suffice to diagnose the cause and location of tissue damage. Other tests and images will be required to diagnose the condition. A high level of LDH-4 or LDH-5 could indicate liver damage or muscle injury. However, a full panel can’t confirm the liver disease.

Your doctor may take regular measurements of your LDH levels to monitor the progress of your treatment. LDH levels can also be used to monitor and predict the body’s response during treatment for certain cancers.

Low LDH Levels

LDH deficiencies affect how sugar is broken down by the body for energy, especially in muscle cells. Low levels of LDH are very rare.

Low levels of LDH can be caused by two types of genetic mutations. Lower than normal LDH levels could indicate a rare genetic condition called Lactate Dehydrogenase A deficiency (Glycogen Storage Disease XI) or Lactate Dehydrogenase B deficiency. A high intake of vitamin C can lead to falsely low LDH tests.

The first type of genetic mutation causes fatigue and muscle pain. This is especially true during exercise. The second type of symptoms may not be present in some people. If you have taken a lot of vitamin C (ascorbic acid), your LDH may be low.

Normal levels of cerebrospinal fluid are:

  • For newborns, less than 70 U/L
  • Adults: Less than 40 U/L

A higher level of Lactate Dehydrogenase or LDH in your cerebrospinal fluid could indicate an infection or inflammation within your central nerve system. You could also have bacterial meningitis, which can affect your brain and spinal cord.

Your doctor may order ALT, AST, or ALP tests if your LDH levels are high. These tests can be used to help diagnose the problem or determine which organs are involved.

However, elevated blood LDH is not always a sign of a problem. This could be due to strenuous exercises. It could also happen if the blood sample was not properly stored or handled in a lab. Too much vitamin D may be the culprit. If your platelet count exceeds normal, then your blood LDH may be high.

Normal or lower than average levels of LDH are not usually a problem.

LDH can be elevated in many medical conditions and diseases. Interpretation of elevated LDH levels depends on many factors including the cause, patient history, physical exam, and laboratory results.

High levels of lactate dehydrogenase may lead to health problems such as:

Shock – An illness in which there is not enough blood, oxygen, or blood to reach tissues or organs

Ischemic liver disease – A liver condition that results in a deficiency of blood or oxygen to its liver

Drug reactions – Possible life-threatening reactions to antidepressants, recreational drugs, or drugs that lower cholesterol.

Tumor-lysis syndrome – A condition that causes the rapid death and destruction of tumor cells

Severe Infections – This includes malaria, pneumonia, and COVID-19

Hemolytic Anemia – A condition in which red blood cells become damaged before they can develop normally.

Cancer – In particular, germ cell tumors in the ovary, testicular, multiple myeloma, and lymphoma.

Muscular Dystrophy – A condition characterized by weakness of muscles and tissue loss

Acute Myocardial Infarction – A heart condition in which blood clots block blood flow to the heart.

Also Read: 4 Blood Tests to Assess Your Heart Health

What To Do in Case of High Levels?

Having higher-than-normal Lactate Dehydrogenase or 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:

  • Anemia
  • Liver disease
  • Kidney disease
  • Lung disease
  • Muscular dystrophy
  • Muscle injury
  • Bone fracture
  • Pancreatitis
  • Heart attack
  • Certain infections, including meningitis, mononucleosis (mono), encephalitis, and HIV
  • Certain types of cancer, including multiple myeloma, metastatic melanoma, lymphoma, leukemia, and testicular cancer

Your LDH test results may show that you have elevated levels of LDH, but that doesn’t necessarily mean you have a medical condition.

There are a few things that can help increase your LDH levels:

  • Strenuous exercise
  • Some medications, like aspirin and anesthetics, and Procainamide
  • An error in sample collection, transport, and/or processing.

Your healthcare provider will take into account your medical history, current medications, and symptoms when interpreting your results. If you require further testing, they will let you know.

Talk to your healthcare provider if you have any questions about your results.

Final Takeaway

Doctors can use LDH measurement to evaluate and treat certain medical conditions. The normal ranges can vary depending on your age. Scientists continue to discover more about LDH’s role in the body. This will make it easier to monitor LDH levels in certain conditions and diseases.


Should I be worried if my LDH is high?

The level of LDH can be higher in case of organ or tissue damage. But the test doesn’t tell you the exact location of the damage. Therefore, normally this test is combined with other further tests in case of high results.

What LDH level is too high?

Normal levels of LDH in the blood can vary depending on the lab, but it is usually between 140 units per liter (U/L) to 280 U/L for adults and higher for children and teens.

Can exercise increase LDH levels?

A study demonstrated that aerobic or intensive exercise like running can increase LDH levels for around 12 to 24 hours.

by Dr. Neeraj Gujar

Dr. Neeraj Gujar has done his M.D. in Pathology from Government Medical College. He has worked at various organisations such as Breach Candy Hospital and Tata Memorial Hospital along with many other private organisations. During his working career, he realised the pressing need for exceptional quality diagnostic services. A diagnostic centre that can consistently give accurate results verified by a consultant doctor (M.D. Pathologist) on which your doctor can depend. This has been the founding principle of Primus Pathology and Diagnostics.

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