ALT is one of the enzymes of the aminotransferase group produced in the liver. It is just an intracellular enzyme. It is one of the tests showing hepatocellular necrosis in the liver. It is mostly found in the liver, with a small amount in cardiac and skeletal muscles.
ALT combines the alanine protein with ketoglutaric acid in the cell, resulting in L-Glutamic acid + Pyruvic acid. This is an important stage of energy metabolism. In liver cell damage, this enzyme comes out together with other liver enzymes and its values increase in the blood.
Although blood ALT normal values were reported as 29 iu/L in men and 22 iu/L in women, changes may also occur due to abdominal adiposity. Different upper limit values can be used in different centers.
ALT mean values:
- Male: 10-55 iu/L
- Female: 7-30 iu/L
ALT is usually a liver-specific enzyme. Since the half-life of ALT (approximately 50 hours) is two to three times longer than that of AST, it may remain elevated for a longer period of time in the blood.
Causes of ALT elevation:
- Chronic HCV
- Chronic HBV
- Acute viral hepatitis (AE, EBV, CMV)
- steatosis
- hemochromatosis
- Medicines and toxic substances
- Medicines
- analgesics
- Acetaminophen
- NSAID
- antibiotics
- Tetracycline
- Sulfonamides
- Isoniazids (INH)
- rifampin
- Trimethoprim sulfamethoxazole
- nitrofurantoin
- cholesterol lowering drugs
- Statins
- niacin
- cardiovascular drugs
- amiodarone
- Hydralazine
- Guinidine
- Alpha-methyldopa
- labetalol,
- ACE inhibitors
- Oral antidiabetics
- Glyburide
- troglidazone
- acarbose
- glipizide
- antidepressants
- trazadone
- bupropion
- Fluoxetine
- Paroxetine
- Sertraline
- Proton pump inhibitors
- Omeprazole etc.
- Methotrexate
- Vitamin A
- Anticonvulsants
- carbamazepine
- Valproic acid
- phenytoin
- phenobarbital
- Alcohol
- Mushrooms
- Heavy metals
- analgesics
- Heart diseases
- endocrine diseases
- hyperthyroidism
- autoimmune causes
- Hematological diseases
- sickle cell anemia
- Thalassemias
- Chronic Graft Versus Host Disease (GVHD)
- Liver malignancies
- amyloidosis
- Muscular dystrophy
- Alpha 1 antitrypsin deficiency
- Wilson’s disease
- celiac disease
- Congenital diseases of fructose metabolism
- Congenital diseases of galactose metabolism
- Glycogen storage diseases
- Congenital disorders of amino acid metabolism
- Congenital disorders of lipid metabolism
- Bile acid metabolism synthesis disorder
- Lysosomal storage diseases
- Cystic fibrosis
- hepatic porphyrias
- fatty liver disease
- Mitochondrial fatty acid oxidation defects
- Urea cycle defects
Evaluation of liver dysfunction by looking only at the level of aminotransferases (AST and ALT) can lead to inaccurate results. For this reason, the patient’s clinic, symptoms and condition are evaluated together with other examinations.
In cases such as alcohol-induced liver damage, fatty liver, hepatitis and cirrhosis, the ALT level is approximately twice the AST level. In viral hepatitis, over 300 IU/L for ALT indicates acute damage. However, since jaundice began to appear later, ALT levels may have dropped at that time. Or jaundice may not be seen at all.
AST and ALT values can increase up to ten times in blockages in the bile ducts. In drug-induced enzyme elevations, the enzymes return to normal one month after the drug is discontinued.
High levels of transaminases can also be observed in cases of excessive exercise, pregnancy and obesity. These enzymes are expected to increase in conditions that cause hemolysis in the blood, muscle diseases, various organ necrosis and ischemia.