ALT and AST

ALT (ALanine Aminotransferase) test is one of the most common tests used to detect liver damage. ALT values are usually compared to the levels of other enzymes, such as aspartate aminotransferase (AST), to help determine which form of liver disease is present.

Here are a few values reported by the Internet users on various medical forums, blogs and microblogging sites:

	Normal	Moderately Elevated									High
ALT	0-55	40	50	59	66	70	92	109	119	214	227	227	258	434	533	670
AST	0-40	37	43	132	106	90	212	122	281	34	131	288	34	72	114	217

According to different sources, normal values are supposed to be between:
4–36 units per liter (U/L) or 0.07–0.62 microKat/L for ALT and 8–35 units per liter (U/L) or 0.14–0.58 microKat/L for AST; 8-20 for both ALT and AST, 0-40/0-45 IU/L for ALT and AST respectively. Lab Corp considers 0-55 IU/L as normal values for ALT, while Covance lists 6-43 U/L.
Some sources list separate references for males and females.

Higher AST were observed for women with a family history of diabetes, when adjusted for age and BMI.

In acute liver injury, such as viral hepatitis, the ALT and AST may be as high as 1000U/L. In chronic hepatitis or cirrhosis of the liver, ALT and AST may be 10 to 100 times their normal values.

Besides severe liver damage, lead poisoning, exposure to carbon tetrachloride, severe drug reactions, necrosis of large tumors and shock, elevated levels of ALT may be caused by:

• Alcohol abuse.
  
• Celiac disease
• Fatty deposits in the liver
• Long-term (chronic) diseases that affect the liver, such as Cirrhosis
• Medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates. People who take acetaminophen (such as Tylenol) can have high ALT blood levels.
• Mononucleosis
• Hepatitis (viral, autoimmune) /ALT can be 20x normal value/
  
• Hereditary hemochromatosis
• Liver ischemia (blood flow deficiency to the liver)
• Liver tumor
• Quickly growing young children
  
• Use of drugs that are poisonous to the liver

ALT test is a part of a liver panel, also known as liver function tests or LFT, is used to detect, evaluate, and monitor liver disease or damage. It usually consists of seven tests that are run at the same time on a blood sample.

ALT - ALanine Aminotransferase, also known as Glutamate-pyruvate transaminase (EC 2.6.1.2), catalyzes the reversible conversion of L-alanine and alpha-ketoglutarate to L-glutamate and pyruvate. It has 2 distinct molecular and genetic forms: one cytoplasmic (soluble) (GPT1) and one mitochondrial (GPT2; MIM 138210).
AST - ASpartate Aminotransferase, also known as Glutamic-oxaloacetic transaminase is a pyridoxal phosphate-dependent enzyme which exists in cytoplasmic and mitochondrial forms, GOT1 and GOT2, respectively. GOT plays a role in amino acid metabolism and the urea and tricarboxylic acid cycles. See also HPRD:00687; MIM:138180; HPRD:00684; MIM:138150


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