Lactate Dehydrogenase (LDH)
- Also Known As:
- Lactic Dehydrogenase
- Lactic Acid Dehydrogenase
Test Quick Guide
Lactate dehydrogenase (LDH) is a marker of cell and tissue damage in the body. While it is normal to have some amount of LDH in the body, high levels are associated with many different diseases and conditions.
LDH measurements can show if tissue damage has occurred and help doctors evaluate certain types of cancer. LDH is frequently measured in a blood sample but may also be tested in other bodily fluids, such as fluids extracted from the central nervous system, chest, or abdomen.
About the Test
Purpose of the test
A lactate dehydrogenase test has a wide range of uses for diagnosing and monitoring medical conditions. Measuring LDH can provide information about tissue and cell damage due to injury or illness. An LDH test is typically interpreted in conjunction with other tests in order to diagnose and monitor a range of diseases and conditions. Lactate dehydrogenase testing may be performed:
- To diagnose and monitor diseases that cause cell damage
- To assess the severity of certain cancers and monitor patients during treatment
- To evaluate abnormal collections of fluids in the body
Because LDH may be used in a wide variety of situations, you may wish to ask your medical team what the purpose of LDH testing is for you.
What does the test measure?
Lactate dehydrogenase is a type of protein, called an enzyme, that helps the body produce energy. LDH is present in tissues throughout your body. The largest amounts of LDH are found in the heart, muscles, kidneys, lungs, and red blood cells.
As new cells form in tissues, older cells are eliminated by the body. This healthy process causes the release of LDH into the blood or body fluids. It is normal to have some LDH present in a blood or fluid sample, since the cells of the body are constantly being renewed.
When tissues are damaged at a faster rate than normal, LDH leaks from the damaged tissue into the blood. An elevated LDH level indicates that tissue damage has occurred. LDH levels may be elevated in a range of illnesses that cause cell injury.
Occasionally, a related test may be used to measure levels of different LDH isoenzymes in the blood. An isoenzyme is a subtype of an enzyme. There are five different LDH isoenzymes. Each differs slightly in structure and the part of the body they usually come from.
When should I get lactate dehydrogenase testing?
A lactate dehydrogenase test may be included with other tests to aid in the diagnosis of disease, to assess the prognosis of certain types of cancer, and to monitor disease progression or response to treatment.
Lactate dehydrogenase testing is often ordered when your health care provider suspects you have an acute or chronic health condition that is causing tissue damage. In particular, conditions that affect the heart, lung, blood, kidney, and liver may be evaluated and monitored with LDH testing.
Acute conditions occur suddenly and may cause serious symptoms. LDH blood testing may be performed when a person has signs of infection, organ failure, or drug reaction.
Chronic conditions develop slowly over time and usually require periodic testing to check for signs of disease progression. LDH blood testing can aid in the diagnosis and monitoring of chronic conditions like anemia and liver diseases, including hepatitis.
LDH testing of other bodily fluids in the brain and spine, chest, or abdomen may be ordered along with other tests to evaluate conditions that cause tissue damage in these areas.
Patients with certain types of cancer including melanoma, multiple myeloma, lymphoma, and testicular cancer may have LDH testing to determine the severity or stage of the disease. LDH testing may also be performed during and after cancer treatment to assess a patient’s prognosis, which describes the likely outcome of the disease.
Because LDH is a nonspecific and general marker of tissue or cell damage, there are many circumstances which may prompt its use. You can ask your health care team about the purpose of LDH testing for your situation.
Finding a Lactate Dehydrogenase Test
How to get tested
LDH tests are typically ordered by a doctor, often at the same time as other tests. Most commonly, you will provide a blood sample for testing at a doctor’s office, clinic, hospital, or other medical setting.
If fluid from your chest or abdominal cavity is being tested for LDH, the procedure to extract the fluid may take place in a medical provider’s office, a treatment room, or hospital. A spinal tap, which is done to collect cerebrospinal fluid from your central nervous system, is usually done in a hospital setting.
Can I take the test at home?
There are currently no commercially available at-home tests for lactate dehydrogenase.
How much does the test cost?
The cost of an LDH test varies depending on factors such as where the test is done, what type of fluid sample was taken for analysis, and whether you have health insurance. When ordered by a doctor, an LDH test is typically covered by insurance, although there may be a copay or deductible. Your doctor’s office, lab, and health insurance company can provide information about any out-of-pocket costs that may be your responsibility.
Taking a Lactate Dehydrogenase Test
Most LDH tests require a blood sample, which is usually taken from your arm in a doctor’s office, health clinic, hospital, or lab.
Lactate dehydrogenase testing may also be performed on other bodily fluids. To learn more about how bodily fluids from different areas of the body are collected and analyzed, please see the information at the appropriate link:
- From the brain and nervous system: Cerebrospinal Fluid (CSF) Testing
- From the chest cavity: Pleural Fluid Testing
- From the abdomen: Peritoneal Fluid Analysis
Before the test
No special preparations are needed for a lactate dehydrogenase blood test.
Special preparation may be needed prior to the collection of other bodily fluids.
During the test
During an LDH blood test, a nurse or other health care provider takes a small amount of blood, usually from a vein in your arm. An elastic band is fastened around your upper arm to make your veins easier to see. Your skin in the area where the needle enters is cleaned with an antiseptic.
A small sample of blood is withdrawn with a needle attached to a collection tube. You may feel a brief stinging sensation when the needle pierces the skin. A blood sample usually takes less than one minute to obtain.
Special procedures are used to withdraw other bodily fluids for analysis.
After the test
After the blood draw is complete, a cotton swab or bandage is used to stop bleeding. You will be instructed to keep this in place for an hour or more.
A blood draw is a low risk procedure. Sometimes, you may experience slight soreness, redness, or bruising in the area where the needle was inserted.
You can resume your normal activities, including driving, after the blood test is over. If you notice any pain, bleeding, or signs of infection after the test, you should call your health care provider’s office.
Procedures to remove other bodily fluids may require you to take special precautions after the extraction.
LDH Test Results
Receiving test results
The health care provider who ordered your LDH test may share the results with you, or you may be able to access them through an online patient portal. LDH test results are usually available within several business days.
Interpreting test results
Your test report will show your level of LDH and include information on the reference ranges applied to your results. Reference ranges are the test result ranges that are considered expected for a healthy individual.
LDH reference ranges are set by the laboratory that is evaluating the blood or fluid sample based on their equipment and methodology. Because reference ranges can vary by laboratory, it is important for a health care provider to help you interpret your test results.
LDH may be elevated in a wide range of diseases and medical conditions. Interpretation of an elevated LDH level depends on several factors, including the reason for the test, the patient’s history and physical exam, and other laboratory test results.
Health problems that may cause elevated lactate dehydrogenase in the blood include:
- Shock: A condition where not enough blood or oxygen reaches tissues or organs
- Ischemic hepatitis: A liver disease caused by a lack of blood or oxygen to the liver
- Drug reactions: Potentially life-threatening reactions to recreational drugs, antidepressants, drugs given to lower cholesterol, and other prescription medications
- Tumor lysis syndrome: A condition caused by the rapid death of tumor cells
- Severe infections: Including malaria, pneumonia, or COVID-19
- Hemolytic anemia: A condition caused by hemolysis, in which red blood cells are destroyed before they finish developing.
- Cancer: In particular, germ cell tumors of the ovary, testicular cancer, multiple myeloma, leukemia, lymphoma, or metastatic melanoma
- Muscular dystrophy: A disease characterized by muscle weakness and loss of tissue
- Acute myocardial infarction: A heart condition that usually occurs when a blood clot blocks blood flow to the heart
Elevations in LDH levels are sometimes seen in seemingly healthy patients. Further investigation is not usually necessary unless other signs or symptoms of disease are present. Children typically have higher normal levels of LDH than adults.
An abnormally low LDH test result is uncommon. High vitamin C or E intake can cause low test results. Lactate dehydrogenase deficiency is a rare genetic disorder that interferes with the body’s ability to create lactate dehydrogenase.
Using lactate dehydrogenase to assess and monitor certain cancers
Measuring LDH can be useful in assessing the severity and progression of cancer. LDH testing may be tested in patients diagnosed with melanoma, multiple myeloma, some non-Hodgkin lymphomas, testicular cancer, and other types of cancer.
After certain cancers are diagnosed, routine testing of LDH may be helpful. Measuring LDH may help doctors to understand how severe the cancer is, how likely it is to respond to treatment, and whether it has returned after treatment. Higher levels of LDH may indicate a greater number of cancer cells are present in the body, which is referred to as a “high tumor burden.”
LDH can also be used as a tumor marker during and after cancer treatment. This means LDH measurements are taken periodically and compared to previous measurements. If LDH decreases, it may be a sign that the cancer is responding to therapy. A rise in LDH may be a sign that the cancer is not responding to treatment or has returned after treatment.
Interpreting lactate dehydrogenase in other bodily fluids
The interpretation of an LDH result can depend on bodily fluid sampled, including:
- Cerebrospinal fluid (CSF): High levels of LDH may be found in the fluid from the central nervous system, called cerebrospinal fluid or CSF, if a bacterial infection or bleeding in the brain is present.
- Pleural fluid: The level of LDH in the fluid taken from the chest area may be compared to the level of LDH in the blood. This can help doctors narrow down the possible source of pleural effusions, which are abnormal fluid collections around the lungs. Higher levels of LDH suggest the presence of injury, infection, cancer, or inflammation.
- Peritoneal fluid: When LDH is tested in fluid taken from the abdomen, called peritoneal fluid, it is compared to the level of LDH in the patient’s blood. High levels of LDH in the peritoneal fluid may indicate an infection, cancer, or a perforation or hole in the bowel.
Are test results accurate?
Although lactate dehydrogenase testing is widely used, it has some limitations. Because LDH is found in many different tissues in the body, it can’t be interpreted without the results of other tests. If an individual has no other symptoms of disease or abnormal test results, the reason for an elevated LDH test result may be unclear.
In addition, certain situations may cause results that are too high or too low even though there is no underlying disease. A higher test result can be caused by strenuous exercise, certain drugs and medications, or improper handling of the blood sample. A lower test result, where the LDH level appears low or normal although there is disease present, is also possible and may be caused by high levels of vitamin C or E in the body.
Do I need follow-up tests?
An elevated LDH test result may prompt additional testing, depending on what medical condition is being diagnosed or monitored. Your medical team can tell you if follow-up testing is necessary and what tests may be ordered.
Repeat LDH testing may be required if your doctor suspects an inaccurate test result. For example, it is possible for red blood cells in a sample to break down and release their contents during the process of being prepared for laboratory testing, which could lead to inaccurate test results.
Questions for your doctor about test results
Working with your health care provider is the best way to understand what your LDH test result means for you. Learn more by asking the following questions:
- What is my LDH test result and is it within the reference range?
- What do you suspect may be causing my elevated LDH level?
- Will other tests need to be done to learn more about what is causing my high LDH level?
- What does my LDH level tell you about the severity and the outlook of my cancer?
- What does my LDH level tell you about how my condition is responding to treatment?
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