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Alanine transaminase

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Title: Alanine transaminase  
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Subject: Elevated transaminases, Liver function tests, Reference ranges for blood tests, Hepatitis, Branched chain aminotransferase
Collection: Biomarkers, Ec 2.6.1, Enzymes, Hepatology, Liver Function Tests
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Alanine transaminase

glutamic-pyruvate transaminase
Identifiers
Symbol GPT
Entrez 2875
HUGO 4552
OMIM 138200
RefSeq NM_005309
UniProt P24298
Other data
EC number 2.6.1.2
Locus Chr. 8 q24.2-qter
Alanine transaminase
Identifiers
EC number 2.6.1.2
CAS number 9000-86-6
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

Alanine transaminase (ALT) is a transaminase enzyme (EC 2.6.1.2). It is also called alanine aminotransferase (ALAT) and was formerly called serum glutamate-pyruvate transaminase (SGPT) or serum glutamic-pyruvic transaminase (SGPT). ALT is found in plasma and in various body tissues, but is most common in the liver. It catalyzes the two parts of the alanine cycle. Serum ALT level, serum AST (aspartate transaminase) level, and their ratio (AST/ALT ratio) are commonly measured clinically as biomarkers for liver health. The tests are part of blood panels.

Contents

  • Function 1
  • Clinical significance 2
    • Elevated levels 2.1
  • See also 3
  • References 4
  • External links 5

Function

ALT catalyzes the transfer of an amino group from L-alanine to α-ketoglutarate, the products of this reversible transamination reaction being pyruvate and L-glutamate.

L-glutamate + pyruvate α-ketoglutarate + L-alanine
Alanine transaminase

ALT (and all transaminases) require the coenzyme pyridoxal phosphate, which is converted into pyridoxamine in the first phase of the reaction, when an amino acid is converted into a keto acid.

Clinical significance

ALT is commonly measured clinically as a part of a diagnostic evaluation of hepatocellular injury, to determine liver health. When used in diagnostics, it is almost always measured in international units/liter (IU/L).[1][2] While sources vary on specific reference range values for patients, 10-40 IU/L is the standard reference range for experimental studies.[1] Alanine transaminase shows a marked diurnal variation.

The ratio of ALT to AST (aspartate transaminase) also has clinical significance.

Elevated levels

Test results should always be interpreted using the reference range from the laboratory that produced the result. However typical reference intervals for ALT are:

Patient type Reference ranges[3]
Female ≤ 34 IU/L
Male ≤ 52 IU/L

Significantly elevated levels of ALT (SGPT) often suggest the existence of other medical problems such as viral hepatitis, diabetes, congestive heart failure, liver damage, bile duct problems, infectious mononucleosis, or myopathy, so ALT is commonly used as a way of screening for liver problems. Elevated ALT may also be caused by dietary choline deficiency. However, elevated levels of ALT do not automatically mean that medical problems exist. Fluctuation of ALT levels is normal over the course of the day, and they can also increase in response to strenuous physical exercise.[4]

When elevated ALT levels are found in the blood, the possible underlying causes can be further narrowed down by measuring other enzymes. For example, elevated ALT levels due to hepatocyte damage can be distinguished from bile duct problems by measuring alkaline phosphatase. Also, myopathy-related elevations in ALT should be suspected when the aspartate transaminase (AST) is greater than ALT; the possibility of muscle disease causing elevations in liver tests can be further explored by measuring muscle enzymes, including creatine kinase. Many drugs may elevate ALT levels, including Zileuton, omega-3-acid ethyl esters (Lovaza),[5] anti-inflammatory drugs, antibiotics, cholesterol medications, some antipsychotics such as risperidone, and anticonvulsants.. Paracetamol may also elevate ALT levels.[6]

For years, the

  • Alanine transaminase at the US National Library of Medicine Medical Subject Headings (MeSH)
  • ALT: analyte monograph; The Association for Clinical Biochemistry and Laboratory Medicine
  • Alanine aminotransferase (ALT) at Lab Tests Online

External links

  1. ^ a b Wang, CS; Chang, Ting-Tsung; Yao, Wei-Jen; Wang, Shan-Tair; Chou, Pesus (2012). "Impact of increasing alanine aminotransferase levels within normal range on incident diabetes". J Formos Med Assoc 111 (4): 201–8.  
  2. ^ Ghouri, N; Preiss, David; Sattar, Naveed (2010). "Liver enzymes, nonalcoholic fatty liver disease, and incident cardiovascular disease: a narrative review and clinical perspective of prospective data". Hepatology 52 (3): 1156–61.  
  3. ^ "Alanine aminotransferase: analyte monograph" (PDF). Association for Clinical Biochemistry and Laboratory Medicine. Retrieved 7 October 2013. 
  4. ^ Paul T. Giboney M.D., Mildly Elevated Liver Transaminase Levels in the Asymptomatic Patient, American Family Physician.
  5. ^ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683599/?tool=pmcentrez Omega-3-acid Ethyl Esters (Lovaza) For Severe Hypertriglyceridemia, Pharmacy and Pherapeutics.
  6. ^ Watkins PB, Kaplowitz N, Slattery JT; et al. (July 2006). "Aminotransferase elevations in healthy adults receiving 4 grams of acetaminophen daily: a randomized controlled trial". JAMA: the Journal of the American Medical Association 296 (1): 87–93.  
  7. ^ Red Cross Donor Requirements

References

See also

[7]

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