Aspartate aminotransferase (AST; Formerly called serum glutamic-oxaloacetic transaminase [SGOT])
المؤلف:
Kathleen Deska Pagana, Timothy J. Pagana, Theresa Noel Pagana.
المصدر:
Mosbys diagnostic and laboratory test reference
الجزء والصفحة:
15th edition , p122-124
2025-10-28
60
Type of test Blood
Normal findings
Adult: 0-35 units/L or 0-0.58 μKat/L (SI units); females tend to have slightly lower values than males
Elderly: values slightly higher than adult values
Children:
0-5 days: 35-140 units/L
< 3 years: 15-60 units/L
3-6 years: 15-50 units/L
6-12 years: 10-50 units/L
12-18 years: 10-40 units/L
Test explanation and related physiology
Because AST exists within the liver cells, diseases that affect the hepatocytes cause elevated levels of this enzyme. This test is used in the evaluation of suspected hepatocellular diseases. The amount of elevation depends on the time after the injury that the blood is drawn. AST is cleared from the blood in a few days. Serum AST levels become elevated 8 hours after cell injury, peak at 24 to 36 hours, and return to normal in 3 to 7 days. If the cellular injury is chronic, levels will be persistently elevated.
In acute hepatitis, AST levels can rise to 20 times the normal value. In acute extrahepatic obstruction (e.g., gallstones), AST levels quickly rise to 10 times the normal value and fall swiftly. In cirrhotic patients, the level of AST depends on the amount of active inflammation.
Serum AST levels are often compared with alanine amino transferase (ALT) levels. The AST-to-ALT ratio is usually greater than 1.0 in patients with alcoholic cirrhosis, liver congestion, or metastatic tumor of the liver. Ratios less than 1.0 may be seen in patients with acute hepatitis, viral hepatitis, or infectious mononucleosis. The ratio is less accurate if AST levels exceed 10 times the normal value.
Patients with acute pancreatitis, acute renal diseases, musculoskeletal diseases, or trauma may have a transient rise in serum AST. Patients with red blood cell abnormalities, such as acute hemolytic anemia and severe burns, also can have elevations of this enzyme.
Interfering factors
• Exercise may cause increased levels.
• Pyridoxine deficiency (beriberi or pregnancy), severe long standing liver disease, uremia, or diabetic ketoacidosis may cause decreased levels.
* Drugs that may cause increased levels include antihypertensives, cholinergic agents, coumarin-type anticoagulants, digitalis preparations, erythromycin, hepatotoxic medications, isoniazid, methyldopa, opiates, oral contraceptives, salicylates, statins, and verapamil.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
• Fasting: no
• Blood tube commonly used: red
• If possible, avoid giving the patient any IM injection because increased enzyme levels may result.
• Record the time and date of any IM injection given.
• Record the exact time and date when the blood test is per formed. This aids in the interpretation of the temporal pattern of enzyme elevations.
Abnormal findings
Increased levels
Liver diseases
- Hepatitis
- Hepatic cirrhosis
- Drug-induced liver injury
- Hepatic metastasis
- Hepatic necrosis (initial stages only)
- Hepatic surgery
- Infectious mononucleosis with hepatitis
- Hepatic infiltrative process (e.g., tumor)
- Skeletal muscle disveases
Skeletal muscle trauma
- Recent noncardiac surgery
- Multiple traumas
- Severe, deep burns
- Progressive muscular dystrophy
- Recent convulsions
- Heat stroke
- Primary muscle diseases (e.g., myopathy, myositis)
Other diseases
-Acute hemolytic anemia
- Acute pancreatitis
Decreased levels
- Acute renal disease
- Beriberi
- Diabetic ketoacidosis
- Pregnancy
- Chronic renal dialysis
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