liver function test continue

Serum albumin
About 10 – 12 gm of albumin is synthesized in liver daily.

Its estimation is very valuable in assessing chronic liver disease.

Low serum albumin level is commonly observed in severe liver disease.



Prothrombin time Normal 11 to 12 seconds

PT is prolonged in severe parenchymal liver disease due to decreased synthesis of prothrombin.

Vitamin K is required for synthesis of prothrombin.

vitamin K deficiency can also lead to prolonged PT.

Note:
If PT returns to normal after vitamin K injection it indicates that hepatocyte function is good.




Transaminases:

ALT(SGPT) 3 to 15 IU/L
AST(SGOT) 4 to 17 IU/L
ALT is primarily localized to the liver. It is the marker enzyme of the liver.
ALT is present in the cytosol of hepatocytes.
AST is present in a wide variety of tissues like heart, liver, skeletal muscle, kidney, brain.
AST is present both in the cytosol and mitochondria of the hepatocytes.


Liver contains both enzymes but more of ALT

Estimation is very useful in assessing severity and prognosis of liver parenchymal disease especially infective hepatitis.

Also very useful as screening test in outbreak of infective hepatitis.


Elevated ALT & AST

Highly elevated > 20 times
Viral hepatitis
Drug or Toxin induced hepatic necrosis

Moderately elevated - 3 to 20 times
Chronic hepatitis
Alcoholic hepatitis
Auto immune hepatitis
Acute biliary tract obstruction


Alkaline Phosphatase( ALP) - 3 to 13 KAU/dl

A family of Zinc metallo enzymes, with a serine at the active center. They release inorganic phosphate from various organic phosphates.

In the liver it is found in microvilli of bile canaliculi and on the sinusoidal surface of the hepatocytes.

Other important sources of ALP is bone.

ALP is highly elevated in obstructive jaundice and bone diseases like rickets.


?-Glutamyl transpeptidase - Normal level 10 – 15U/L

It is a membrane bound glycoprotein which catalyses the transfer of ?- glutamyl group to other peptides and AAS.
Very useful in diagnosis of obstructive jaundice.
(not elevated in bone diseases)
It is a microsomal enzyme.
Serum GGT is highly elevated in obstructive jaundice and alcoholic liver disease.

This enzyme is an inducible enzyme.


5’ – Nucleotidase - Normal 2 to 15 U/l

It is elevated in obstructive jaundice.
Advantage of this enzyme is that it is not elevated in bone disease.

Test for assessing detoxification function of liver.

Hippuric acid test:
Principle :
Hippuric acid is produced in the liver when benzoic acid combines with glycine.

Procedure :
6 gm of sodium benzoate is given to the patient.
Urine is collected upto 4 hours
Hippuric acid excreted in urine is estimated.
6 gm of sodium benzoate forms 7.5 gm of hippuric acid.