A lactate dehydrogenase (LD or LDH) test is a non-specific test that may be used in the evaluation of a number of diseases and conditions. LD is an enzyme that is found in almost all of the body's cells (as well as in bacteria) and is released from cells into the fluid portion of blood (serum or plasma) when cells are damaged or destroyed. Thus, the blood level of LD is a general indicator of tissue and cellular damage. The level of LD may also rise in other types of body fluids (e.g.,cerebrospinal fluid, pleural fluid, etc.) in the presence of certain diseases.

An LD blood test may be used:

• As a general indicator of the existence and severity of acute or chronic tissue damage

• To detect and monitor progressive conditions such as anemia, including hemolytic anemia and megaoloblastic anemia, or severe infections

• To help stage, determine prognosis, and/or monitor treatment (i.e., chemotherapy) of cancers, such as germ cell tumors (e.g., some types of testicular cancer and ovarian cancer), lymphoma, leukemia, melanoma, and neuroblastoma

An LD test is performed on body fluids for a few different reasons:

• To help evaluate cerebrospinal fluid and distinguish between bacterial or viral meningitis

• To evaluate other body fluids such as pleural, peritoneal or pericardial fluid and help determine whether the accumulation of fluid is due to injury and inflammation (exudate) or due to an imbalance of pressure within blood vessels and the amount of protein in the blood (transudate). This information is helpful in guiding treatment.