Liver Funtion Test(d)

8/3/2019 Liver Funtion Test(d)

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LIVER FUNCTIONTESTS


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Tests that are of very much useful todiagnose and monitor the liver diseases arecalled as liver function tests.


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Functions of liver Excretion of bile pigments,

bile salts,BSP(Bromsulphthalein ) andICG(indocyanin green)

Metabolism of

carbohydrates, amino acidsand lipids.

Synthesis of serum proteins albumin and prothrombin.

Detoxification of ammoniaand hippuric acid.

Serum enzymes.


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Classifiation

Tests based on Excretory function

Tests based on synthetic function.

Tests based on metabolic capacity of liver

Tests based on serum enzymes.


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Tests based on Excretory function

BILIRUBIN

It is the excretory product formed due tocatabolism of heme.

It is conjugated by the liver to form bilirubindiglucuronide and excreted through bile.

Normal levels varies from 0.2-0.8mg/dl

Unconjugated bilirubin- 0.2 0.6mg/dl Conjugated bilirubin- 0-0.2mg/dl


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Estimation of bilirubin in serum

By Van den bergh reaction.

Diazotised sulfanilic acid + bilirubin

Azobilirubin( The red-violet compound)

Conjugated bilirubin Direct positive

Unconjugated bilirubin Indirect positiveBoth - biphasic


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Urinary findings in jaundice

Type of

jaundice

Bile

pigment

Bile

salt

Uro

bilinogen

Prehepatic Nil Nil ++

Hepatocellular

++ + Normal ordecreased

Posthepatic

+++ ++ Nil ordecreased


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Tests in urine

Bile pigmentsFouchets test.

Bile salts Hays test

Urobilinogen Ehrlichs test.


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Jaundice Jaundice is increased levels of Ser Bil > 1.0 mg%.

Latent jaundice - >1mg%,


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Table of diagnostic tests

Function test Pre-hepaticJaundice

HepaticJaundice

Post-hepaticJaundice

Total bilirubin Normal /Increased

Increased

Conjugated bilirubin Normal Increased

Unconjugated bilirubin Normal /

Increased

Normal

Urobilinogen Normal /Increased

Decreased /Negative

Urine Color Dark

Stool Color Pale

Alkaline phosphatase levels Increased

ALT and AST levels Increased

Conjugated Bilirubin in Urine Present

Increased


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BSP(Bromsulphthalein RETENTION TEST)

The ability of the liver to excrete certain dyes isutilized in this test.

PROCEDURE

A single bolus dose of BSP 50g/L, is given & theserum concentration is measured at 45mins & at

2hrs.

Normal response the retention at 45mins is


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Tests based on metabolic capacity of liverGalactose tolerance test

Galactose is almost exclusively metabolised byliver.

The rate of utilisation of galactose is proportionalto the functional liver mass.

Procedure- 350mg galactose/kg body weight isgiven intravenously within 3mins. Then blood iscollected at 10mins interval for 1hour.

The half life of galactose in blood is about 10-15mins in normal people.

The half life is increased in cirrhosis and infectivehepatitis patients.

C14 labelled galactose given CO2 eliminated may be assessed.


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Plasma amino acids

Theamino acid profile is abnormal in hepatic coma.

The level of aromatic amino acids is increased.

Tests based on abnormalities of lipids

Total cholesterol 150-250mg%, & 60 -70% of this isesterified.

Obstructive jaundice increase in TC A/c Hepatic necrosis TC is usually low and may fall

below 100mg%, and also marked decrease in % ofesters.


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Tests based on synthetic function

Blood albumin level

1.all serum proteins are synthesised by the liverexcept immunoglobulins.

2.Serum albumin is quantitatively the mostimportant protein synthesised by the liver andreflects the functioning of liver cell mass.

3.it is not a good indicator of acute liver diseasesas its half life is long. In chronic diseases its level

is decreased.4.normal level Albumin 3.5 5g/dl.

Globulin 2.5 3.5g/dl

Reversal cirrhosis


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Prothrombin time

Prothrombin is synthesised by the liver.

Vit K deficiency as the cause for prolonged PTmay be ruled out by estimating the PT beforeand after parenteral administration of Vit K.

In case of liver disease the PT remainsprolonged even after administration of vit K.

Prolonged PT poor prognosis.

T t b d d t ifi ti f ti f


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Tests based on detoxification function ofliver

HIPPURIC ACID TEST

Liver removes benzoic acid by combining withamino acid glycine forming hippuric acid.

Test depends on 2 factors

1. ability of the liver to produce and provide sufficientglycine

2. the capacity of liver cells to conjugate with benzoicacid


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ProcedureDissolve 6 gms of sodium benzoate in200 ml of water . The patient is asked to drink this

solution and time is noted . (bladder should be

emptied before consuming the solution).

The bladder is again emptied 4 hours later.

The amount of hippuric acid excreated in this 4 hours

is estimated. Interpretation normally 3 gm of hippuric acid

should be excreted.

In liver disorders - either acute or chronic small

amounts are excreted.

T t b d


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Tests based on serum enzymes.

SGOT (AST) -


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Marker enzymes for obstructive liver disease ALP - 12-115U

GGT- 10

30U/L 5nucleotidase - 2-10U/L

Leucine amino peptidase.

ALP

ALP is an ecto

enzyme that is localised in cellmembranes & is associated with transportmechanisms in liver, kidney & intestinal mucosa.

Very high levels cholestasis or hepatic ca.

The bile duct obstruction induces the synthesis by thebiliary tract epithelial cells.

Parenchymal liver diseases mild elevation


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GGT :

It transfers gamma glutamyl residues.

Moderate elevations seen in infectivehepatitis and prostrate cancer, MI, panreaticdisease, renal failure, COPD.

Highly elevated in alcoholism, obstructivejaundice and neoplasms of the liver.

GGT elevation parallels that of ALP & is

very sensitive to biliary tract disease.


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5'Nucleotidase It is a marker enzyme for plasma

membranes ans is seen as an ecto-enzyme.

It is moderately increased in hepatits

and highly elevated in biliary obstruction. It parallels the levels of ALP.

Leucine amino peptidase

Elevated levels noticed in hepatobiliary disease,obstructive jaundice and pregnancy.


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Liver Funtion Test(d)