About the Test
Purpose of the test
An LDH 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 to diagnose and monitor various diseases and conditions. LDH 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 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?
LDH 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. It is also present in many cancers, such as lymphoma and myeloma.
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 in a blood or fluid sample since the body’s cells are constantly being renewed.
When tissues are damaged faster 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 body part they usually come from. In general, LDH isoenzymes are not clinically useful.
When should I get this test?
An LDH test may be included with other tests to aid in diagnosing disease, assessing the prognosis of certain types of cancer, and monitoring disease progression or response to treatment.
LDH testing is often ordered when your health care provider suspects you have an acute or chronic health condition causing tissue damage. In particular, conditions that affect the heart, lungs, 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 you have signs of infection, organ failure, hemolysis (premature breakdown of red blood cells), 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 diagnosing and monitoring 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.
If you have certain types of cancer, including melanoma, multiple myeloma, lymphoma, and testicular cancer, you 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 your 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 that may prompt its use. You can ask your health care team about the purpose of LDH testing for your situation.
Finding a Lactate Dehydrogenase (LDH) Test
How can I get a Lactate Dehydrogenase (LDH) test?
LDH tests are typically ordered by a doctor, often at the same time as other tests. You will usually provide a blood sample for testing at a doctor’s office, clinic, hospital, or another medical setting.
If fluid from your chest or abdominal cavity is being tested for LDH, extracting the fluid may take place in a medical provider’s office, a treatment room, or a hospital. A spinal tap, which collects 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 LDH.
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. An LDH test is typically covered by insurance when ordered by a doctor, 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 (LDH) 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.
LDH 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 generally needed for an LDH blood test, although your doctor may prescribe some prior to the collection of other bodily fluids. Always follow the instructions provided by your doctor.
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 blood sample 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 just a few minutes to obtain.
Special procedures are used to obtain 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 needle’s insertion area.
You can resume your normal activities, including driving after the blood test. If you notice any pain, bleeding, or signs of infection after the test, call your health care provider’s office.
Procedures to remove other bodily fluids may require you to take special precautions after the extraction.
Lactate Dehydrogenase (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. It is typically reported as units per liter (U/L). Reference ranges are the test result ranges considered expected for a healthy individual.
LDH reference ranges are set by the laboratory 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, your history and physical exam, and other laboratory test results.
Health problems that may cause elevated LDH 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, which typically occurs after the start of treatment
- Severe infections: Including malaria, pneumonia, or COVID-19
- Hemolytic anemia: A condition caused by hemolysis, in which red blood cells are destroyed prematurely
- 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. LDH deficiency is a rare genetic disorder that interferes with the body’s ability to create LDH.
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 my cancer’s severity and outlook?
- What does my LDH level tell you about how my condition responds to treatment?