SGPT (ALT, Alanine aminotransferase, Serum Glutamic-Pyruvic Transaminase)

Sample

1. This is done on the serum of the patient.
2. The Blood sample can be taken at any time.
3. The fasting sample is not necessary.
4. Analyze the enzyme on the same day because the enzyme activity is lost at room temperature.
5. This enzyme is stable in whole blood up to 12 to 24 hours; after that time, there is a gradual increase due to release from the RBCs.
6. The sample can be stored at 4 °C for 1 to 3 days (ALT is stable when refrigerated).
   1. ALT, when freezed, shows deterioration.

Precautions

1. Avoid hemolysis because RBC contains increased ALT (SGPT) and AST (SGOT).
2. Drugs that may increase the SGPT value are acetaminophen, aminosalicylic acid, ampicillin, allopurinol, cephalosporin, chlorpropamide, clofibrate, cloxacillin, codeine, indomethacin, INH, Methyldopa, methotrexate, nalidixic acid, quinidine, phenylbutazone, phenytoin, salicylates, tetracycline, and propanol.
3. Ideally, perform the test as soon as possible or on the same day because the sample’s storage may not be satisfactory.
4. Previous I/M injection may increase the level.

Indications

1. Diagnose liver diseases.
2. Monitor liver diseases after the treatment.
3. It differentiates jaundice from liver disease or hemolytic anemia.

Pathophysiology

1. Definition of ALT (SGPT):
   1. This enzyme catalyzes the reversible transfer of amino groups between an amino acid, and α-keto acids are called aminotransferase or transaminases.
   2. One of the aminotransferases is Alanine aminotransferase (ALT), or the old name was glutamate-pyruvate transaminase (SGPT) which will catalyze the reversible transfer of the amino group between an amino acid and α-keto acid where vitamin B6 (pyridoxal phosphate) is the co-factor.
      

      SGPT (ALT) biochemical reaction

2. Distribution of SGPT (ALT):
   1. ALT is an enzyme found predominantly in the liver.
   2. It is distributed in many tissues, a moderate amount in:
      1. 1. Kidneys.
      2. A small amount in:
         1.  Heart, skeletal muscles.
   3. A minimal amount may be found in the pancreas, spleen, lungs, and RBCs.
3. Variation of the ALT:
   1. The day-to-day variation of the ALT is 10% to 30%, and there is diurnal variation.
   2. ALT is 45% higher in the afternoon than in the early morning.
   3. Until the age of 15, ALT is higher than the AST; after that, AST is higher than the ALT.
   4. In few people, this pattern may reverse after the age of 60.
   5. Exercise is the major determinant for AST and but less for ALT in men.
      1. Strenuous exercise or bodybuilding increase 3 fold AST and 50% increase in ALT.
      2. The effect of the exercise is minimal in the women.
4. Distribution of SGPT (ALT) in the liver:
   1. This enzyme is present in cytosolic and mitochondrial forms in the liver. The majority of the SGPT is present in the cytoplasm of liver cells.
   2. There is always a low level of this enzyme in the blood.
   3. This is a liver-specific enzyme of the transferases.
   4. The liver hepatocytes contain 3 to 4 times more AST (SGOT) than the ALT (SGPT).
   5. This is also normally found in bile, CSF, and saliva.
   6. It is not found in the urine unless there is a kidney lesion.

SGPT distribution in the liver cell

5. Liver cell injury: Any damage to the liver cells, SGPT enzyme, is released, specifically for liver cell necrosis.
6. 1. 1. First cytosolic SGPT is released, and in the case of necrosis, then mitochondria SGPT is released into circulation.
         

         SGPT level depends upon the number of liver cells injured

         

         SGPT level depends upon the number of cells injured

6. SGPT activity persists longer than the SGOT.
7. This enzyme is raised before there are clinical findings of jaundice.
8. In viral hepatitis, the SGPT/SGOT ratio is greater than 1.
9. Other than the viral cause, the SGPT/SGOT ratio is less than 1.

SGPT (ALT) biochemical reaction and variations in different conditions:

1. ALT catalyzes the reaction, and it is reversible.
2. Pyridoxal-5‘- phosphate  (P-5-P) functions as coenzymes in the amino-transfer reaction.
   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, alanine, to form enzyme-bound pyridoxine-5- phosphate, and the first reaction product is pyruvate.
   3. This coenzyme increases the ALT activity by 20% in the normal serum.
   4. Hemolysis increases both AST and ALT because of this enzyme activity in the RBCs in comparison to serum. This effect is greater for AST than ALT.
      

      SGPT (ALT) reaction principle

3. SGPT 1.5 to 8 times more than the normal level seen in:
   1. Early, late and subclinical hepatitis.
   2. Chronic hepatitis.
   3. Alcoholic hepatitis.
   4. Chemical hepatitis.
   5. Passive congestion with centrilobular necrosis.
   6. Rye’s syndrome.
   7. Cholangitis.
   8. Hemochromatosis.
4. SGPT >8 to 10 times more than the normal value seen in:
   1. Mostly in acute viral hepatitis.
5. SGPT >30 times more than the normal value is seen in:
   1. Drug toxicity like acetaminophen in alcoholics and malnourished people.

SGPT level compared to serum (1 unit) in the heart is 450 times; the liver is 2850 times, the kidney is 1200 times, skeletal muscle is 300 times, the pancreas is 130, the spleen is 80 times, the lung is 45 times, and RBCs 7 times.

SGPT (ALT) level in various tissues as compared to the serum (one unit)  are:

Organs	Times more as compared to the serum normal level
Liver	2850
Kidneys	1200
Heart	450
Skeletal muscle	300
Pancreas	130
Spleen	80
Lungs	45
RBCs	7
Serum	1

AST/ALT ratio:

1. The ALT is the cytoplasmic enzyme in the liver, while AST is both cytoplasmic and mitochondrial enzyme with a wide distribution in the various other tissues.
   1. AST/ALT ratio normally is <1, but in the liver, infectious hepatitis becomes greater.
2. AST/ALT ratio is usually greater than 1 in:
   1. The patient with alcoholic liver diseases (cirrhosis). AST is more sensitive to alcoholic liver disease.
   2. Liver congestion.
   3. Metastatic tumor of the liver.
3. AST/ALT ratio of less than 1 is seen in:
   1. Acute hepatitis.
   2. Viral hepatitis.
   3. Infectious mononucleosis.
      1. The ratio will be less accurate if the AST level is more than 10 times the normal.

         Ratio of enzymes	<1	>1
         AST/ALT	Acute hepatitis Viral hepatitis with extensive hepatocellular necrosis Infectious mononucleosis	Alcoholic liver diseases (Cirrhosis) Alcoholic patient with acetaminophen, causing extensive liver cell necrosis. Liver congestion Metastatic tumor infiltration of the liver Myocardial infarction Rhabdomyolysis Hemolytic anemia

4. Diagnostic application of the SGPT (ALT):
   1. The best indicator for liver cell injury when both SGPT and SGOT are raised.
      1. Higher-level are found in hepatocellular disorders than the extrahepatic or intrahepatic obstructive lesions.
      2. Levels of both enzymes may reach as high as 100 times. 20 to 50 times, the elevated level is frequently found.
   2. Measuring aminotransferases weekly is useful in hepatitis or other hepatic injuries.
   3. Because of the accurate measuring techniques, it can detect liver cell injury due to alcohol.
   4. It is used as a screening test for diagnosing hepatitis due to hepatotropic viruses, especially the hepatitis C virus in blood donors.
   5. 5 to 10 times the elevation of both ALT and AST occurs in the liver’s metastatic carcinoma. AST (SGOT) level is higher than the ALT (SGPT). In the early stages of malignant infiltration of the liver, these enzymes are normal.
   6. ALT (SGPT) may be raised after intake of alcohol, delirium tremors, and after the administration of the drugs like opiates, salicylates, and ampicillin.

NORMAL

Source 4

Age	Male U/L	Female U/L
Newborn 12 months	13 to 45	13 to 45
one to 60 years	10 to 40	7 to 35
60 to 90 years	13 to 40	10 to 28
>90 years	6 to 38	5 to 24

Source 2

• Adult / child = 4 to 36 unit/L at 37 °C
• Elderly = slightly higher than the adult
• Infants = Maybe twice high as the adult

Another source

• Men = 10 to 30 units /L (some labs normal is 10 to 40 U/L).
• Women = 9 to 25 units /L (Some labs normal is 10 to 28 U/L).
• Children two times of adult’s value.
  • In children, it is raised because of bone activity, and that is normal for children.
  • The adult level is achieved by 6 months of age.
  • Males are slightly higher than females.

The Increased SGPT (ALT) Level Is Seen In:

1. Viral hepatitis. There is markedly increased the level.
2. Drug-induced hepatitis.
3. Chronic hepatitis.
4. Infectious mononucleosis.
5. Intrahepatic cholestasis.
6. Cholecystitis.
7. Active cirrhosis.
8. Metastatic tumors of the liver.
9. Obstructive jaundice.
10. Alcoholic cirrhosis.
11. The mild increase is seen in :
    1. Myosotis.
    2. Pancreatitis.
    3. Myocardial infarction.
    4. Shock.
    5. Infectious mononucleosis.
12. Alcohol-acetaminophen syndrome.
13. A significant increase in level has been in acute liver diseases.
    1. Moderately increase level is seen in chronic diseases of the liver and trauma to muscles.
    2. A mildly increased level is seen in myositis, Myocardial infarction, and infectious mononucleosis.

Acute Viral Hepatitis SGPT (ALT) Pattern:

1. This rises before the appearance of jaundice.
2. Peak level occurs between 7 to 12 days of jaundice.
3. Then there is a gradual decrease in the level.
4. Normal level after 3 to 4 weeks of the onset of jaundice.
5. AST/ALT ratio, which is normally <1, becomes greater >1.
   

   SGPT level in the viral hepatitis

Table Showing The Increase Of SGPT In Various Conditions:

Clinical Condition	The Rise In SGPT Level With Reference To The 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	maybe raised
Extrahepatic cholestasis	Very high level
Cirrhosis	4 to 5 times or higher
Metastatic carcinoma	5 to 10 times
Acute myocardial infarction	within normal limits or a very mild increase
Progressive muscular dystrophy	May reach 8 times
Dermatomyositis	May reach 8 times

Critical value = >9000 U/L  seen in Alcohol-acetaminophen syndrome.

This level can distinguish from alcoholic or viral hepatitis.

Comparison of AST/ALT

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.