Lactate Dehydrogenase (LD) Isoenzymes Blood Test

What is the purpose of this test?

Order this Lactate Dehydrogenase (LD) Isoenzymes Blood Test, which measures LD levels in the blood to assess tissue damage severity. There is a protein called LD that works as an enzyme to aid in energy production within the body. LD can be found in various tissues throughout the body, with the highest concentrations being in the lungs, kidneys, heart, muscles, and red blood cells. Unfortunately, LD is also present in various types of cancer, including lymphoma and myeloma.

As the body eliminates older cells and new ones form, some LD is released into the blood or other fluids. This is perfectly normal since the body is constantly renewing cells. However, when tissues are damaged at a faster rate, LD can leak from the damaged area and enter the bloodstream. If this happens, it may indicate that tissue damage has occurred. LD levels can be elevated in many illnesses that cause cell damage.

What analytes are included in this test?

LD is classified into five isoenzymes present in various amounts throughout the body. This test detects and measures these five LD isoenzymes:

• LDH-1: located in the heart and red blood cells
• LDH-2: located in white blood cells. It is also found in heart and red blood cells, but in lesser amounts than LDH-1.
• LDH-3: located in lung tissue
• LDH-4: located in white blood cells, kidney and pancreas cells, and lymph nodes
• LDH-5: located in the liver and muscles of the skeleton

When should I order an LD Isoenzymes Blood Test?

Individuals may order this test if suspected of having an acute or chronic health condition causing tissue damage. In particular, conditions that affect the:

• Heart
• Lungs
• Blood
• Kidneys
• Liver