Different Liver Function Test are:
- Determination of Bilirubin
- Determination of SGPT and SGOT
- Alkaline Phosphatase
- Gamma Glutamyl Transpeptidase (GGT)
- Galactose Tolerance
- Serum Albumin
- Prothrombin Time
- Hippuric Acid Synthesis
Determination of Bilirubin
Bilirubin is the byproduct of the heme. In the liver, bilirubin is conjugated with diglucuronide and is excreted in bile. There is a specific reaction by which identification for an increase in the level of bilirubin can be done. This reaction is called the Van den Bergh reaction and it is a mixture of sulfanilic acid and sodium nitrite in equal concentrations. The principle of the reaction is based on the diazotization reaction. In which diazotized sulfanilic acid get reacts with bilirubin to produce azobilirubin which is in purple color form and that can be measured by a colorimeter or Spectro-photometrically. High laboratory test values represented for the various form of bilirubin such as; conjugated, unconjugated and a mixture of both indicate the medical condition of an obstructive form of jaundice, hemolytic jaundice, and hepatic jaundice respectively.
Determination of SGPT and SGOT
Another name of SGPT is alanine transaminase (ALT) and it is specifically increased in hepatic diseases such as liver damage, hepatic jaundice, liver cirrhosis, metastatic carcinoma, drug-induced liver diseases, etc. SGOT is a gold/direct marker for the identification of hepatocellular damage or injury. While SGOP, a name by aspartate transaminase (AST) which is useful and count as an indirect marker for the identification of liver injury.
The basic principle or reaction associated with estimation is SGPT produces pyruvate and SGOT produces oxaloacetate and this get reacts with 2, 4-dinitrophenyl hydrazine to produce dinitrophenyl hydrazone which shows brown in alkaline medium and that can be measured at colorimeter or spectrophotometer at 505 nm. Higher laboratory test results for SGPT compared to SGOT indicates chronic liver disease while higher test results for SGOT represent chances of cirrhosis and acute alcoholic hepatitis.
Alkaline phosphatase (ALP) is an enzyme and mainly it is obtained from bone and liver cells. The normal level of ALP is 3 -13 KA units/dl. An increase in the level of ALP indicates the bone resorption process which may lead to osteoporosis. An elevated level of ALP is also another indicator of the high level of bilirubin due to the biliary obstruction which is observed in hepatic jaundice, liver cirrhosis, and hepatic tumor.
Gamma Glutamyl Transpeptidase (GGT)
GGT is a microsomal enzyme and it is widely distributed in body tissues, including the liver. The normal level of GGT is 5-4O lU/D. An elevated level of GGT is indicated in the condition of biliary obstruction and alcoholism.
Galactose is a monosaccharide and is exclusively metabolized by the liver. Thus, liver function can be assessed by estimating the utilization of galactose. This high level of galactose indicates poor functioning of the liver and vice-versa. Generally, the test of galactose is performed by blood withdrawal at the interval of 10 minutes for the next 2 hours of food ingestion. The half-life of galactose in normal individuals is around 10-15 minutes. The elevated level of galactose is also an indicator of hepatocellular damage, liver cirrhosis, and infective jaundice.
It is a protein and it is an important indicator for testing of live function. A low value of protein indicates the damaging of the liver while a high level of albumin indicates impairment of liver functions.
Clotting factors are essential for the blood clot process and these factors are synthesized in the liver. Impairment of liver function is demonstrated by an increase in the bleeding tendency which is associated with a decrease in the concentration of clotting factors. So, this can be assessed by estimating prothrombin time. The test is generally performed on the non-heparinized blood sample. Prolonged prothrombin time indicates impairment in the liver function or liver damage compared to normal.
Hippuric Acid Synthesis
Synthesis of hippuric acid takes place in the liver and is a product of benzoic acid and glycine. The liver is the major source of organs for detoxification and estimation of hippuric acid synthesis is an ideal method the assessing the function of the liver. An increase in the concentration of hippuric acid indicates hepatic damage. Normally around 60% of sodium benzoate which is equivalent to 4.5 gm of hippuric acid is eliminated in urine. The normal concentration of hippuric is less than 3 gm.
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