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Nov 27 2011

Learn the Lab Test: Lactate Dehydrogenase (LDH)

LDHLDH is one of those lab tests that is frequently ordered and has several different uses. It is hard to remember everything it can be used for, because it spans so many different topics. Therefore, I think it deserves its own post to put all the details in one place.

Lactate dehydrogenase (LDH) is an enzyme located in the cytoplasm of many cells in the body. It is located in numerous organs, including skeletal muscle, heart, liver, red blood cells, lungs, kidneys, and brain. LDH can be elevated in any condition that causes tissue breakdown of these organs.

LDH can be increased in the following conditions:

  • Hemolytic anemia
  • Skeletal myopathies (from muscle damage)
  • Liver disease (such as hepatitis)
  • Myocardial infarction (however, has been replaced by troponin)
  • Interstitial lung diseases
  • Pneumocystis carinii (jirovecii) pneumonia (PCP)
  • Lymphoma (specifically precursor T cell lymphoblastic lymphoma, adult T cell leukemia/lymphoma, and anaplastic large T/null cell lymphoma)
  • Toxoplasmosis
  • Tuberculosis
  • Type II glycogen storage disease (Pompe disease)

LDH can also be used for the following:

  • As a component of Light’s criteria to determine if a pleural effusion is transudative or exudative
  • As a component of Ranson’s criteria to determine the prognosis for acute pancreatitis
  • As a tumor marker for lymphoma, Ewing’s sarcoma, and testicular germ cell tumors
  • Determining staging and prognosis for testicular germ cell tumors
  • Determining prognosis for non-Hodgkin’s lymphoma
  • Determining staging for Hodgkin’s lymphoma
  • Determining prognosis for carcinoma of unknown primary

As you can see above, LDH has a wide variety of applicable uses. The main thing to remember is that LDH is located inside the cell and gets released when the cell is damaged.

References:
Fauci, Anthony S., and Tinsley Randolph Harrison. Harrison’s Principles of Internal Medicine. 17th ed. New York: McGraw-Hill Medical, 2008. Print.
Jaffe, AS. Biomarkers of cardiac injury other than troponins and creatine kinase. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2011.
Kaplan, MM. Liver function tests that detect injury to hepatocytes. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2011.
Miller, ML. Approach to the patient with muscle weakness. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2011.
Stover, DE. Approach to the HIV-infected patient with pulmonary symptoms. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2011.
Vorvick, Linda J., James R. Mason, and David Zieve. “Lactate Dehydrogenase Test: MedlinePlus Medical Encyclopedia.” National Library of Medicine – National Institutes of Health. MedlinePlus, 21 Mar. 2010. Web. 27 Nov. 2011. <http://www.nlm.nih.gov/medlineplus/ency/article/003471.htm>.

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