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LDH isoenzymes

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Contents of this page:

Illustrations

Blood test
Blood test

Alternative Names    Return to top

LD; Lactic (lactate) dehydrogenase isoenzymes

Definition    Return to top

LDH isoenzymes is a test to check how much lactate dehydrogenase (LDH) is in the blood.

How the Test is Performed    Return to top

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell 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 band 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.

In infants or young children, 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. A bandage may be applied to the puncture site if there is any bleeding.

How to Prepare for the Test    Return to top

The health care provider may tell you to stop taking certain medicines before the test.

How the Test Will Feel    Return to top

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed    Return to top

This test is usually done when your doctor thinks you might have high LDH levels. Measurement of LDH isoenzymes helps determine the location of tissue damage.

LDH is found in many body tissues like the heart, liver, kidney, skeletal muscle, brain, blood cells, and lungs.

LDH exists in 5 forms, which differ slightly in structure.

All of these can be measured in the blood.

What Abnormal Results Mean    Return to top

Because LDH can be found in many tissues in the body, total LDH is not specific for heart disease.

Normally, the level of LDH-2 is greater than LDH-1. However, after a heart attack, LDH-1 is generally higher than LDH-2. This is called a "flipped" LDH pattern.

The LDH level rises within 24 - 72 hours after a heart attack, peaks in 3 - 4 days, and returns to normal in about 14 days.

Greater-than-normal LDH levels may suggest:

Risks    Return to top

Considerations    Return to top

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.

Update Date: 1/22/2007

Updated by: Benjamin W. Van Voorhees, MD, MPH, Assistant Professor of Medicine and Pediatrics, The University of Chicago, Chicago, IL. Review provided by VeriMed Healthcare Network.

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