SGOT (Aspartate aminotransferase, AST, Glutamic oxaloacetic Transaminase)

Sample

1. This is done on the serum of the patient.
2. A random sample can be used.
3. The serum is stable for 24 hours at room temp. and 28 days at 4 °C.

Precautions

1. Avoid hemolysis because RBC contains AST and ALT, which will increase the value.
2. Avoid any I/M injection, which will increase the SGOT level.
3. Pregnancy may cause a decrease in the AST level.
4. Exercise may increase the AST level.
   1. Another source of error increase in the ALT and AST level after exercise.
5. Alcohol use will affect the result.
6. False decreases occur in diabetic ketoacidosis, severe liver disease, and uremia.
7. There is a false decreased level in:
   1. Pyridixoin deficiency (Beriberi).
   2. Severe long-standing liver diseases.
   3. Uremia.
   4. Diabetic ketoacidosis.
8. Drugs that may increase the value are:
   1. Antihypertensive.
   2. Digitalis preparation.
   3. Erythromycin.
   4. Anticoagulants like coumarine.
   5. Oral contraceptives.
   6. Isoniazid.
   7. Salicylates.
   8. Opiates.
   9. Hepatotoxic drugs.
   10. Methyldopa.

Purpose of the test (Indications)

1. This is done in suspected liver diseases.
2. This also helps in heart diseases to diagnose acute myocardial infarction.
3. It helps in D/D of AMI and liver disease.

Pathophysiology

5. Definition of  AST (SGOT):
   1. Definition of AST:
      1. Aspartate transaminase is also known as L-aspartate-2-oxoglutarate aminotransferase, AST.
      2. This enzyme catalyzes the reversible transfer of amino groups between an amino acid, and α-keto acids are called aminotransferase or transaminases.
         

         SGOT basic reaction

      3. One of the aminotransferases is Aspartate aminotransferase (AST), or the old name was glutamic -oxaloacetic transaminase (GOT).
6. Distribution of the SGOT (AST) in the body:
   1. This enzyme is distributed in all tissues (primarily all the tissues), but the highest concentration is found in the liver, heart, and skeletal muscles.
      1. AST (SGOT)  concentration is more in heart >liver> muscles>kidneys>pancreas.
   2. According to concentration, SGOT is found in descending order:
      1. Cardiac muscle.
      2. Liver.
      3. Skeletal muscles.
      4. Kidney.
      5. Brain.
      6. Lungs.
      7. Pancreas.
   3. High concentration was seen in the cardiac muscle and liver.
      1. Intermediate concentration in skeletal muscle and kidneys.
      2. Much lower level in other tissues.
      3. Minimal activity (small amount) occurs in the skin, kidneys, pancreas, and RBCs.
      4. SGOT is found in the plasma, bile, CSF, and saliva.
      5. It is not found in urine unless there is a kidney lesion.
   4. This enzyme exists in two isoenzyme fractions:
      1. In the liver, it is present in cytosolic (cell cytoplasm), and the second form is mitochondrial.
      2. The intracellular concentration of the SGOT enzyme is 7000 times as compared to extracellular concentration.
      3. The cytoplasmic fraction isoenzyme is predominant in the serum.
         

         Distribution of the SGOT in the liver cell

7. AST and ALT are increased at birth to 2 to 3 times of the adult level; this will fall to the adult level by 2 to 4 months.
8. Compared to serum, the SGOT level is 7800 times in the heart, 7100 times in the liver, skeletal muscles 5000 times, kidney 4500 times, pancreas 1400 times, spleen 700 times, lungs 500 times,  and RBCs 15 times.
   SGOT (AST) level in various tissues as compared to the serum (one unit):

   Organs	AST times more as a comparison to serum as one unit
   Heart	7800
   Liver	7100
   Skeletal muscle	5000
   Kidneys	4500
   Pancreas	1400
   Spleen	700
   Lungs	500
   RBCs	15
   Serum	1 (one unit)

9. Liver cell Injury:
   1. The injury to cells leads to the release of the SGOT into the blood circulation and causes an elevation in the SGOT level.
   2. SGOT is present in the cytoplasm and the mitochondria.
   3. In the blood, there is cytosolic and mitochondrial SGOT (AST).
      

      Liver cell injury response to SGOT level

   4. After the injury, SGOT (AST) rises in the blood around 8 hours, and the peak level is 24 to 36 hours and returns to normal in 3 to 6 days.
   5. There is only a transient rise in the SGOT (AST) level in case of minor injury, and even it may not be noticed.
   6. In Acute viral hepatitis, there is a rise >10 times the normal in 75% of the cases in one study and 100% in another study.

4. SGOT (AST) biochemical reaction:
   1. AST catalyzes the biochemical reaction, and it is reversible.
      1. The P-5-P is bound to the apoenzyme and serves as a true prosthetic group.
      2. The P-5-P bound to the apoenzyme accepts the amino group from the first substrate, aspartate, to form enzyme-bound pyridoxine-5- phosphate, and the first reaction product is glutamate. Pyridoxal-5‘- phosphate  (P-5-P) functions as coenzymes in the amino-transfer reaction.
         

         SGOT (AST) biochemical reaction

5. SGOT (AST) and variations in different conditions:
6. SGOT level 1.5 to 8 times more than the normal indicates:
   1. Early, late, and subclinical viral hepatitis.
   2. Chronic hepatitis.
   3. Alcoholic hepatitis.
   4. Hepatitis due to chemicals.
   5. Reye’s syndrome.
   6.  Cholangitis
   7. Passive congestion with centrilobular necrosis.
7. SGOT >8 to 10 time more than the normal indicates:
   1. Acute viral hepatitis.
8. SGOT >30 times more than the normal seen in:
   1. Alcoholic patients taking acetaminophen.
   2. In acute extrahepatic obstruction like gallstones.  The SGOT level rises to 10 times the normal value, and it normally returns quickly when the obstruction is relieved.

Distribution in various organs and degree of a raised level of SGOT (AST):

SGOT (AST) level rise	Causes of raised SGOT (AST)
1.5 to 8 times raised	Liver diseases: Early, late, and subclinical viral hepatitis Chronic hepatitis Alcoholic hepatitis CHemical hepatitis Passive congestion with centrilobular necrosis Hemochromatosis Cholangitis Reye’s syndrome Heart diseases Acute myocardial infarction Pericarditis Rhabdomyolysis Acute pancreatitis Pulmonary infarction Hemolytic anemia
>8 to 10 times raised	Acute viral hepatitis
>30 times raised	Malnourished patient Alcoholic patient with acetaminophen

4. Diagnostic application of SGOT:
   1. It is released into circulation and can diagnose the following conditions:
   2. in liver diseases. The level may reach 100 times above the normal limit.
      1. In cirrhosis, there is a moderate increase, which may be around 4 times the normal limit.
      2. The amount of SGOT is directly related to the number of cells affected by the disease or injury.
      3. In chronic injury, the elevated level will persist.
      4. In Acute hepatitis, the level may increase 20 times to the normal.
   3. Heart diseases: After congestive heart failure, there is a rise in the SGOT level due to less blood supply to the liver.
      1. There is a rise after 6 to 8 hours of the damage or chest pain in myocardial infarction. Abnormal values are seen almost in more than 97% of the cases.
      2. This test is advised in hepatocellular diseases and coronary occlusive diseases leading to muscle necrosis.
   4. Renal infarction.
   5. Brain infarction.
   6. Skeletal muscle diseases. This is seen in muscular dystrophy and inflammatory conditions, and the level may reach  4 to 8 times the normal value.
   7. There is an elevation in pulmonary embolism.

1. The AST/ALT ratio usually >1 is seen in:
   1. The patient with alcoholic cirrhosis.
   2. Liver congestion.
   3. Metastatic tumor of the liver.
   4. The AST/ALT  ratio of <1 is seen in:
      1. Acute hepatitis.
      2. Viral hepatitis.
      3. Infectious mononucleosis.
      4. The ratio will be less accurate if the AST level is more than 10 times normal.

Normal

Source 1

Age	U/L
Newborn	25 to 75
Infants	15 to 60
Adult	8 to 20
>60 years	Male = 11 to 60
	Female = 10 to 20

Source 2

• Newborn/ infants  = 15 to 60 units/L
• Child = Value like an adult
• Adult = 0 to 35 units/L

Elderly = Slightly higher than the adults

Source 4

• Men = 14 to 20 U/L  (0.23 to 0.33 µKat/L).
• Women = 10 to 36 U/L  (0.23 to 0.33 µKat/L).
• Newborn = 47 to 150 U/L  (0.23 to 0.33 µKat/L).
• Children = 9 to 80 U/L  (0.23 to 0.33 µKat/L).

Another source

• Newborn = 25 to 75 U/L
• Infants = 15 to 60 U/L
• Adult
  • Male = 15  to 40 U/L at 37C.
  • Female = 13 to 35 U/L at 37C.
  • Elderly = slightly higher than the adult.
• SGOT > 450 U/L in blunt abdominal injury is an indicator of liver injury.

Source 6

Age	Normal values U/L
0 to 5 days	35 to 140
<3 years	15 to 60
3 to 6 years	15 to 50
6 to 12 years	10 to 50
12 to 18 years	10 to 40
Adult	0 to 35 (female slightly low than males)
Elderly	slightly higher than the adults

Increased SGOT (AST) level seen in:

1. Fulminant type of hepatitis especially viral type.
2. In liver cell necrosis or injury like chronic hepatitis.
3. Alcoholic hepatitis.
4. Cirrhosis depends upon the cell’s activity.
   1. In inactive cirrhosis, usually AST level is normal.
   2. In, active cirrhosis the AST level is mild to moderately raised. AST level is <5 times the upper limit, and in 95% of the cases, the upper limit is <10 times the normal value.
   3. One study showed that in 15% of the cases upper limit was >10 times the normal, which may be due to superimposed infection by the viruses.
5. In cholestatic and obstructive jaundice.
   1. There is no rise in the enzyme unless there is secondary damage to the liver tissue.
   2. The elevation is mild to moderate, <10 times the normal value.
   3. When the obstruction is extrahepatic, there is a rapid rise in AST >10 times the normal. It falls rapidly after 72 hours.
6. Liver metastasis and Hepatoma (increase maybe 5 to 10 folds and is of both enzymes).
   1. Around 50% of the liver’s metastatic infiltrate shows a <5 times increase in the AST level.
7. In necrosis of heart muscle or skeletal muscle, e.g, acute myocardial infarction.
8. In infectious mononucleosis, in 88% to 95% of the cases, AST is raised. Only 5% of the patients show >10 times the normal value.
   1. 2% may show >20 times the normal value.
9. Severe exercise.
10. Severe burn.
11. Hypothyroidism ( in 40 to 90% of cases).
12. May see a transient increase in acute pancreatitis, acute renal diseases, musculoskeletal diseases, or trauma.
13. Other diseases than liver and heart which can increase the level:
    1. Hypothyroidism.
    2. Dermatomyositis.
    3. Polymyositis.
    4. Gangrene.
    5. Toxic shock syndrome.
    6. Shock.
    7. Mushroom poisoning.
    8. Pulmonary embolism and infarction.
    9. Hemolytic anemia.
    10. Malignant hyperthermia.

Raised level of SGOT (AST) according to the organs involved:

Organ involved	Causes of raised SGOT (AST)
Heart	Acute myocardial infarction Pericarditis in some cases Cardiac surgery Cardiac catheterization and angioplasty
Liver	Acute viral hepatitis Hepatic necrosis Involvement by other viruses like: CMV Epstein -Barr virus Active cirrhosis Alcoholic liver disease Drugs induced liver disease Severe fatty liver Extrahepatic biliary obstruction Metastatic infiltrate Hepatic surgery
Skeletal muscles	Muscle inflammation (infective or non-infective) Acute skeletal muscle injury Muscular dystrophy Recent surgery Multiple traumas Severe deep burns Heat strokes Primary muscle disease like myopathy, and myositis
Kidneys	Renal infarct Acute damage or injury to the kidneys
Miscellaneous causes	Acute hemolytic anemia Intestinal infarction Acute cholecystitis Acute pancreatitis Heparin therapy in 60% to 80% of the cases Intestinal infarction Hypothyroidism

Decreased SGOT (AST) level seen in:

1. Chronic renal dialysis.
2. Acute renal diseases leading to Azotemia.
3. Vit.B6 deficiency.
4. Beriberi.
5. Pregnancy.

Acute Myocardial infarction (AMI) SGOT pattern:

1. The SGOT level will be raised, but this is not a specific test but useful when there is a raised level of Creatine phosphokinase(CPK) and Lactic dehydrogenase(LDH).
2. In Myocardial Infarction:
   1. SGOT appears in 6 to 8 hours after the onset of chest pain. This rise is 3 to 5 times normal.
   2. The peak level is between 18 to 24 hours.
   3. Returns to normal in 4 to 6 days, unless there is no new infarct.
      1. The average increase in MI is 4 to 5 times normal.
      2. The increase of 10 to 15 times indicates massive MI (fatal infarcts).
      3. The abnormal level is seen in >97% of the patient if it is done at the right time.
         

         SGOT curve in Acute Myocardial Infarction

3. A myocardial injury like Angina, pericarditis, and rheumatic carditis does not rise in the level.
4. The small increase in the SGOT level does not indicate a favorable prognosis.
5. ALT (SGPT) is usually within normal limits, or rarely only marginally increased, in uncomplicated myocardial infarction; this is because of the small amount of ALT activity in the heart muscles.

Liver diseases SGOT pattern:

1. There is a raised level of SGOT in liver cell necrosis. This may be a 10 to 100 times increase.
   1. 20 to 50 times elevations are frequent.
   2. Peak values are seen on the 7th or 12th days.
   3. Then the activity decreases and the normal level reaches by 3rd to 5th week in case of uneventful recovery.
   4. SGOT (AST) also rises in toxic hepatitis like infectious hepatitis.
2. The SGOT level may be compared with SGPT.
3. SGOT/SGPT ratio is usually greater than 1 in a patient with alcoholic cirrhosis, liver congestion, and metastatic tumors of the liver.
   1. A ratio of <1 may be seen in acute hepatitis and viral hepatitis.
4. Acute viral hepatitis:
   1. The rise of SGOT was seen before the onset of jaundice.
   2. Peak level has been seen from 7 to 12 days after the onset of jaundice.
   3. The normal level has been seen  3 to 4 weeks after the onset of jaundice.
   4. Characteristically SGPT is greater than SGOT.
      

      SGOT rise in the viral hepatitis

Table showing the increase of SGOT in various conditions:

Clinical conditions	The rise in SGOT level with reference to normal value
Viral hepatitis and liver diseases	May reach 100 times
Infectious hepatitis	ALT > AST
Toxic hepatitis	Extremely high level
Infectious mononucleosis	20 times
Intrahepatic cholestasis	lower values
Extrahepatic cholestasis	Increased value
Cirrhosis	Normal to 4 to 5 times
Metastatic carcinoma	5 to 10 times
Acute myocardial infarction	4 to 5 times
Fatal myocardial infarction	10 to 15 times
Progressive muscular dystrophy	May reach 8 times
Dermatomyositis	May reach 8 times
Pulmonary emboli	2 to 3 times
Acute pancreatitis	2 to 5 times
Crushed muscular injury, Gangrene	2 to 5 times
Hemolytic diseases	2 to 5 times

Critical value: >20,000 U/L seen in alcohol-acetaminophen syndrome.

Comparison of AST (SGOT) / ALT (SGPT)

1. AST (SGOT) is always is raised in acute myocardial infarction, where ALT (SGPT) will be normal unless there is damage to the liver.
2. ALT  (SGPT) is more raised in acute hepatobiliary obstruction than AST (SGOT).
3. ALT (SGPT) is more specific than AST (SGOT) for liver cell injury.
4. The AST/ALT ratio is higher in alcoholic liver diseases.
5. AST (SGOT) is more sensitive to alcoholic liver cell injury.

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