LDH
Definition
LDH is a blood test that measures the amount of lactate dehydrogenase (LDH).
See also: LDH isoenzymes
Alternative Names
Lactate dehydrogenase; Lactic acid dehydrogenase
How the Test is Performed
The health care provider draws blood from a vein or from a heel, finger, toe, or earlobe. The laboratory quickly spins (centrifuges) the blood to separate the serum (liquid portion) from the cells. The LDH test is done on the serum.
How to Prepare for the Test
Your health care provider may ask you to stop taking drugs that may affect the test. Drugs that can increase LDH measurements include anesthetics, aspirin, clofibrate, fluorides, mithramycin, narcotics, and procainamide.
Why the Test is Performed
LDH is most often measured to check for tissue damage. The enzyme
LDH is in many body tissues, especially the heart, liver, kidney, skeletal muscle, brain, blood cells, and lungs.
LDH affects the chemical reaction for the conversion of pyruvate and lactate
. Exercising muscles convert (and red blood cells metabolize
) glucose to lactate. Lactate is released into the blood and is later taken up by the liver. The liver converts lactate back to glucose and releases glucose into the blood. Resting muscles, red blood cells, and other tissues then take up this glucose.
Normal Results
Normal values may vary slightly from one lab to another. A typical range is 105 - 333 IU/L (international units per liter).
What Abnormal Results Mean
Higher-than-normal levels may indicate:
If the LDH level is raised, your doctor may order an LDH isoenzymes measurement.
Other conditions under which the test may be done:
References
Abeloff MD, Armitage JO, Niederhuber JE, Kastan MB, McKenna WG. Clinical Oncology
. 3rd ed. Philadelphia, Pa: Churchill Livingstone, 2004.
Ferri FF. Ferri's Clinical Advisor 2007
. Philadelphia, Pa: Mosby, 2006.
