This test is usually performed when elevated LDH levels are suspected. Measurement of LDH isoenzymes is helpful in determining the location of the tissue damage.
The enzyme LDH is found in many body tissues like the heart, liver, kidney, skeletal muscle, brain, blood cells, and lungs. LDH is very important for metabolism.
LDH exists in 5 forms -- isoenzymes, which differ slightly in structure. LDH-1 is found primarily in heart muscle and red blood cells. LDH-2 is concentrated in white blood cells. LDH-3 is highest in the lung. LDH-4 is highest in the kidney, placenta, and pancreas. LDH-5 is highest in the liver and skeletal muscle. All of these isoenzymes can be measured in the blood.
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