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Lactate Dehydrogenase (LDH)
Intracellular enzyme
Found in the cells of many body tissues: Heart, liver, RBC, kidneys, skeletal muscle,
brain, and lungs.
When these cells become injured, they lyse
& LDH enters the blood stream.
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NADNicotinamide-Adenine Dinucleotide
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An enzyme that is composed of two types ofsubunits, M and H (formally A and B), eachencoded by a different gene. M stands for
muscle and H for heart.
The M subunit is encoded by LDHA
The H subunit is encoded by LDHB
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The protein itself is tetrametric.
It can have one of the following isozymes:
HHHH or H4 (also called LDH1)HHHM or H3M (also called LDH2)
HHMM or H2M2
(also called LDH3)HMMM or HM3 (also called LDH4)MMMM or M4 (also called LDH5)
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Lactate dehydrogenase (LDH)
This is an example in which two duplicated geneshave become specialized to different tissues
My main LDH is HM3. Great!
Developmental stages Main isoenzyms in heart
Before birth M4 (LDH-5)At birth HM3 (LDH-4)
1 year after birth H2M2 & HM3 (LDH-3 & 4)
After 2 year H3M & H4 (LDH-2 & 1)
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Enzyme levels in various tissues
TISSUE Enzyme levels (IU/g)
Liver 9.000
Heart 25.000
Kidney 15.000
Skeletal muscle 9.000
Lung 9.500
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LDH PredominantlyPercentage (%)
In Serum In the lung
LDH1 Heart, blood cells 1930 10
LDH2 Reticuloendothelial system,white blood cells
3248 20
LDH3 Lung 12 22 30
LDH4 Kidney, placenta, pancreas 5 11 25
LDH5 Liver, striated muscle 513 15
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Cerebrovascular accident (CVA, stroke) Drugs: anesthetics, aspirin, narcotics, alcohol (ethanol) Haemolitic Anaemia
Pernicious anemias (megaloblastic anemias) Intestinal and pulmonary infarction Kidney disease Liver disease
Muscular dystrophy
Pancreatitis Testicular cancer, lymphoma or other cancers
With some chronic and progressive conditions
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Increasing levels Diseases
LDH1 Miocard Infark (MI)
LDH1 > LDH2 Testicular tumors
LDH2 & 3 Pulmonary disease : CHF, embolism, infark,pneumonia, lymphoma & other reticuloendothelialtumors, AIDS,
LDH4 Pancreatitis, Kidney disease
LDH5 Liver disease (hepatitis, cirrhosis, neoplasm),
ischemic bowel disease, striated muscle disease(muscular dystrophy, strenuous sxercise)
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An increase in airway LDH activity mightarise from diverse sources, including:
1) rupture (necrosis) of airway and/or
alveolar epithelial cells or other
pulmonary cell types;
2) pulmonary injury (e.g. oedema,
haemorrhage);
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Inflammatorymarkers
LDH-3
establish a diagnosis additional supporting
information
-Rarely be measured- controversial- nonspesific
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Pneumonia Pleuraleffusion
Parapneumoniceffusion
(Empyema)
LDHlevels
COMPLICATION
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Thoracentesis
Lights criteria:
Exudate vs Transudate
Pleural fluid LDH / serum LDH> 0.6
Pleural fluid protein / serum protein > 0.5
Pleural fluid LDH > 2/3 ULN serum LDH
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Laboratory
Laboratory Meaning
LDH > 1000 U/LEmpyema, Malignancy,Rheumatoid
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Although certain LDH patterns are classicfor certain diseases, it is highly sensitive butnon-specific test
There are other tests/enzymes that aremore specific
Can it be an important adjunct - yes?
e.g. differentiating angina from heart attack e.g. differentiate hepatic disease from benign
condition
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THANK YOU
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Vorvick, L. and Zieve, D. (Updated 2009 March 14). LDH isoenzymes.MedlinePlus Medical Encyclopedia [On-line information] Availableonline athttp://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.Accessed October 2011.
Gaston B. Pneumonia. Pediatr Rev 2002;23(4):132140.
Donald Janner MD. Community Acquired Pneumonia in PediatricInfectious Disease, Copyright 2004 Lippincott Williams & Wilkins.
Blood Test: Lactate Dehydrogenase (LDH). KidsHealth from NemoursFoundation [On-line information] Available online athttp://kidshealth.org/parent/system/medical/test_ldh.html throughhttp://kidshealth.org. Accessed October 2011.
Respir J, 1996, 9,Usefulness of lactate dehydrogenase and itsisoenzymes as indicators of lung damage or inflammation 17361742DOI: 10.1183/09031936.96.09081736 Printed in UK - all rights reserved
http://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.%20Accessed%20October%202011http://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.%20Accessed%20October%202011http://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.%20Accessed%20October%202011http://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.%20Accessed%20October%202011http://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.%20Accessed%20October%202011http://www.nlm.nih.gov/medlineplus/ency/article/003499.htm.%20Accessed%20October%202011Top Related