Alternate Names: Lactate dehydrogenase; Lactic dehydrogenase
How Performed: Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How To Prepare: The health care provider may advise you to withhold drugs that may affect the test (see special considerations).
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:
How It Feels: When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Risks:
- excessive bleeding
- fainting or feeling lightheaded
- hematoma (blood accumulating under the skin)
- infection (a slight risk any time the skin is broken)
- multiple punctures to locate veins
Why Performed: LDH is most often measured to evaluate the presence of tissue damage.
The enzyme LDH is in many body tissues, especially the heart, liver, kidney, skeletal muscle, brain blood cells and lungs. LDH catalyzes the interconversion of pyruvate and lactate.
Exercising muscles convert (and red blood cells metabolize) glucose to lactate. Lactate is released into the blood and eventually taken up by the liver. The liver converts lactate back to glucose and releases glucose into the blood. This glucose is then taken up by resting muscles, red blood cells, and other tissues.
Normal Values: 105 to 333 IU/L
Note: IU/L = international units per liter
Abnormal Results: Greater-than-normal levels may indicate:
Note: if the LDH level is elevated, the health care provider will often recommend measurement of LDH isoenzymes.
Additional conditions under which the test may be performed:
Cost:
Special Considerations: Drugs that can increase LDH measurements include anesthetics, aspirin, clofibrate, fluorides, mithramycin, narcotics, and procainamide.
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
