Lactate Dehydrogenase (LDH) Test

The human body needs energy as fuel to complete its day-to-day tasks. The fuel is produced by proteins called enzymes. And these enzymes are often present in every cell of your body. Sometimes they’re more than you may need and vice versa.

There are different types of enzymes present in the body of a human, but one of the most important is LD or LDH (Lactate Dehydrogenase). This enzyme is part of the energy production for every cell of the body, mainly in the heart, lungs, kidneys and muscles and blood cells.

The LDH test is recommended by the doctor to measure the amount of LDH enzyme present in fluids, such as blood and others. When the cells present in the human body are damaged or destroyed, the enzyme LDH is released in the fluid portion of the body, i.e., the blood.

The amount of LDH present in the blood is very low compared to the cells of the human body. The results of the LDH test, however, reveal that it is considered to be a very non-specific marker to measure the presence of damaged tissue in the organism. Many studies conclude that elevated serum levels of lactate dehydrogenase (LDH) are indicative of cytokine-mediated tissue damage and release of LDH, which is a predictor of poor outcomes.

The LDH test result is often considered so inaccurate that by itself, it cannot be trusted to identify the location or cause of the cellular damage. But that’s not all there is to the LDH test; it is often used in conjunction with other blood tests to monitor or evaluate severe diseases of the heart and brain, especially the kind of tissue damage that leads to cancer.

In conditions like injury, inflammation or infection around a certain region of the body, like the brain, heart and lungs, the fluid version of LDH is accumulated or its constituents are usually changed. The result of the LDH test will reveal the levels of LDH present in the body as a form of fluid, which in turn helps the doctors to determine the cause of tissue damage.

The LDH enzymes are typically high in cerebrospinal fluid (liquid produced in the brain that surrounds the brain and the spinal cord) when the human has bacterial meningitis(Spinal Meningitis). The LDH test results, when combined with tests, can be useful in determining the cause of damaged tissues around cells, such as the heart, brain and lungs. Serum LDH was validated for its potential usefulness as a marker for evaluating clinical severity and monitoring treatment response in COVID-19 pneumonia.

Other names of LDH test

• Lactic Acid Dehydrogenase test
• LD test

What does the test detect/measure and who is this prescribed for?

 The necessity of the LDH test in COVID is undeniable in a word and this is the reason why a large number of doctors are suggesting to go for the test. This test can help the experts determine the presence of tissue damage. On the other hand, it can help in predicting acute respiratory distress syndrome in those patients who have been affected by SARS-COV-2. In other words, it can be passively considered as one of those tests that can help you determine the presence of the deadly respiratory disease in you and this is why the test is necessary in COVID.

Also, routinely the consulting doctor that you are seeing may ask you to take the LDH test for a varied number of reasons. The most common ones are:

• To evaluate and monitor severe infections.
• To monitor conditions like hemolytic and megaloblastic anaemias.
• To monitor kidney diseases.
• To monitor lung diseases, especially ARDS.
• To evaluate certain cancers in your body like CLL.
• To evaluate the treatment of cancer.
• To monitor the severity of COVID-19 infection.

Your doctor may order you to have an LDH test of body fluids to:

• To find the reason for fluid build-up.
• To learn if you have bacterial meningitis.

Note: In conditions like cancer and treatment of cancer, you may have to be regularly tested for LDH.

A blood sample will be drawn from the veins of your forearms. In the case of cerebrospinal fluid, a sample is collected by lumbar puncture (a thin needle is inserted in your lower back).

Test preparation

No special preparation is required for this test. For the LDH test, a blood sample is required, which is collected from the forearm’s prominent vein commonly. During this test, minimal pain at the needle prick site is felt. After this test, you can immediately resume duty except for critical hospitalised cases.

Test inclusions: What parameters are included?

The LDH test includes the following parameters:

• Measurement of tissue damage.
• Monitoring and evaluation of severe lung, brain and heart diseases.
• Monitoring infections.
• Monitoring chemotherapy for cancers.
• Evaluation of cancer treatment.
• Management of COVID-19 infection.

Clinical severity and monitoring treatment response in COVID-19 pneumonia, Management of cancer therapy, Monitoring various injury, inflammation and infection severity

The levels of LDH may differ in males and females, but this is known as the formal normal range for the LDH test results.

The normal values, parameters and reference ranges of the test may vary from lab to lab. Please refer to the ranges mentioned in the report and consult a doctor to understand the interpretation of lab reports.

The LDH test is typically in conjunction with other tests to get accurate results of the damaged or destroyed tissues.

The higher levels of LDH shown in the results may mean you might have some level of tissue damage.