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    LDH isoenzymes

    LD; Lactic (lactate) dehydrogenase isoenzymes

    LDH isoenzymes is a test to check how much of the different types oflactate dehydrogenase (LDH)are in the blood.

    How the Test is Performed

    The procedure is done in the following way:

    • The site is cleaned with germ-killing medicine (antiseptic).
    • The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
    • The health care provider gently inserts a needle into the vein.
    • The blood collects into an airtight vial or tube attached to the needle.
    • The elastic band is removed from your arm.
    • The needle is removed.
    • The puncture site is covered to stop any bleeding.

    In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. Afterward, a bandage may be placed over the area if there is any bleeding.

    How to Prepare for the Test

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

    Drugs that can increase LDH measurements include:

    • Anesthetics
    • Aspirin
    • Clofibrate
    • Fluorides
    • Mithramycin
    • Narcotics
    • Procainamide

    How the Test Will Feel

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

    Why the Test is Performed

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

    LDH is found in many body tissuessuch asthe heart, liver, kidney, skeletal muscle, brain, blood cells, and lungs.

    LDH exists in 5 forms, 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 can be measured in the blood.

    What Abnormal Results Mean

    LDH levels that are higher than normal may suggest:

    • Heart attack (though this test is no longer used routinely to diagnose a heart attack as there are more accurate methods)
    • Hemolytic anemia
    • Hypotension
    • Infectious mononucleosis
    • Intestinal ischemia (blood deficiency) and infarction (tissue death)
    • Ischemic cardiomyopathy
    • Liver disease such as hepatitis
    • Lung tissue death
    • Muscle injury
    • Muscular dystrophy
    • Pancreatitis
    • Lung tissue death
    • Stroke


    Veins and arteries vary in size from one patient to another and from one side of the body to the other.Drawing blood from some people may be more difficult than from others.

    Other risks associated with having blood drawn are slight but may include:

    • Excessive bleeding
    • Fainting or feeling light-headed
    • Hematoma (blood accumulating under the skin)
    • Infection (a slight risk any time the skin is broken)


    Pincus MR, Abraham NZ Jr, Carty RP, et al. Clinical enzymology. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 20.

    Chinnery PF. Muscle diseases. In: Goldman L, Schafer AI, eds. In: Goldman’s Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 429.


    • Blood test


      • Blood test


      Tests for LDH isoenzymes

      Review Date: 1/26/2013

      Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.

      The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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