Lactate Dehydrogenase (LDH) Test

The lactate dehydrogenase (LDH) test is a laboratory procedure used to measure the level of LDH enzyme in the blood or other bodily fluids, such as cerebrospinal fluid or tissue samples.

What is Lactate Dehydrogenase (LDH)?

Lactate dehydrogenase (LDH) is an enzyme found in nearly all living cells. It plays a crucial role in the process of cellular respiration, where it helps convert lactate to pyruvate, allowing cells to generate energy.

Why is the LDH Test Performed?

The LDH test is performed for several reasons:

• Tissue damage detection: Elevated levels of LDH in the blood can indicate tissue damage or cell death, as LDH is released into the bloodstream when cells are damaged.
• Cancer diagnosis and monitoring: High levels of LDH have been associated with certain types of cancer, such as lymphoma, leukemia, and germ cell tumors. The test can help diagnose and monitor these conditions.
• Heart disease diagnosis: Elevated LDH levels can indicate heart damage or myocardial infarction (heart attack).
• Lung disease diagnosis: High LDH levels have been linked to certain lung diseases, such as pneumonia and pulmonary embolism.
• Central nervous system disorders: The test can help diagnose conditions affecting the central nervous system, such as meningitis or encephalitis.

How is the LDH Test Performed?

The LDH test typically involves a blood sample, which is drawn from a vein in the arm using a needle and collected into a tube. The sample is then sent to a laboratory for analysis.

Interpretation of Results

The results of the LDH test are usually reported as units per liter (U/L) or international units per liter (IU/L). Normal ranges may vary depending on the laboratory and the individual's age, sex, and other factors. Elevated levels of LDH can indicate tissue damage or disease.

Types of LDH Tests

There are five main types of LDH isoenzymes, which are different forms of the enzyme:

• LDH-1: Found primarily in heart muscle and red blood cells.
• LDH-2: Present in reticuloendothelial tissues, such as lymph nodes and spleen.
• LDH-3: Found in lungs, kidneys, and pancreas.
• LDH-4: Present in skeletal muscle, liver, and placenta.
• LDH-5: Found primarily in liver and striated muscle.

The LDH isoenzyme test can help identify the source of elevated LDH levels by measuring the specific types of LDH present in the blood or other bodily fluids.