23172860 Liver Function

8/2/2019 23172860 Liver Function

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LIVER FUNCTION TESTSAND LIVER DISEASES

Prof. Fang ZhengDepartment of Laboratory MedicineSchool of Medicine, Wuhan University


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Anatomy of Liver

Functions of Liver

Tests of Liver Function

Liver Diseases

How to use biochemical tests of liverfunctions?

Content


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INTRODUCTION The liver is divided into four lobes.


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THE STRUCTUREOF LIVER


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The portal vein carries blood that has alreadypassed through the capillary bed of thegastrointestinal tract.

The hepatic artery carries well-oxygenatedblood to the liver. Both circulations mix in a vast network ofhepatic sinusoids and leave the liver via thehepatic vein. Sinusoids are lined byendothelial and Kupffers cells.

LOBES VASCULAR ANDBILIARY SYSTEMS


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LOBES VASCULAR ANDBILIARY SYSTEMS

In the liver the ductules merge into bileducts, hepatic ducts, and eventually thecommon hepatic ducts .Their bile drains into the right and lefthepatic ducts.


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Liver Function

1. Synthesis secretionplasma proteins,bile

2. Metabolism ofcarbohydrate

lipid, proteinvitamins, hormonebile acids, bilepigment, drug andtoxins

3. Detoxification (bio-

transformation)


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TESTS OF LIVERFUNCTION1.Tests of Protein Metabolism2. Tests of Bil irublin Metabolism3. Dye intake and Excretion4. Biochemical Serum Enzyme Tests5. Tests of Viral Hepatitis6. Other tests


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Tests of ProteinMetabolism1. Serum total protein (TP), albumin (A) and globulin(G)

2. Serum protein electrophoresis

3. Hepatic neoplasm markers


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Serum total protein (TP),albumin (A) and globulin(G)Albumin

Albumin is quantitatively the most important plasmaprotein synthesized by the liver and thus is a useful

indicator of hepatic function. Albumin has a fairly longhalf-life in serum (20 days) and hence is not a goodindicator of hepatic protein synthesis in acute liverdisease.

Serum albumin levels are depressed in alcoholiccirrhosis.A crude measure of the livers synthetic capacity

hypoalbuminaemia: advanced chronic liver diseasesevere acute liver damage


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Globulin: The main proteins in serum. Total serum globin: the severity of

liver disease

Serum total protein (TP),albumin (A) and globulin(G)


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Reference Value Alb 40-55g/L TP 60-80g/L Globulin 20-30g/L


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Densitometric scan of a normal serum protein electrophoresispattern showing the relative position of the albumin,1,2, and

regions

Serum protein electrophoresis


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Hepatic neoplasmmarkers

alpha-fetoprotein(AFP): primaryhepatocellular carcinoma

Carcinoembryonic antigen(CEA): livermetastatic carcinoma or other carcinomas ofthe gastrointestinal system.


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Normal 400ng/mL

Reference Value(AFP)


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OTHER SERUM PROTEINSPRODUCED BY THE LIVER

Coagulation factors (prothrombin time)1) The liver synthesizes six coagulation factors:

factors(fibrinogen),II(prothrombin),V,VII,and X.

Only substantial impairment in the livers ability to

synthesize these proteins can result in clotting

abnormalities

2) Prolongation of the prothrombin time is not specific

for liver disease.


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Tests of Bil irublinMetabolism Serum total bi l irubin(STB) Conjugated bil irubin Urobil inogen


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Bil irubin Metabolism1) Bilirubin is the principal degradation product of

heme.

2) Bilirubin transport and conjugation in the

hepatocyte.

3) The generally accepted reference range for normalplasma bilirubin concentrations in healthy persons,

which includes 95 per cent of all individuals values, is

1.7 to 17.1umol/L.


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Bilirubinmetabolism


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Bil irubinBilirubin is derived from the tetrapyrrole prostheticgroup found in haemoglobin and the cytochrome. It isnormally conjugated with glucuronic acid to make itmore soluble, and excreted in the bile.Both conjugated bilirubin and unconjugated bilirubinmay be present in plasma. Conjugated bilirubin iswater soluble, unconjugated bilirubin is not, and bindsto albumin. Bilirubin is neurotoxic, and if its levels risetoo high in neonates, permanent brain damage canoccur.


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BILIRUBINBilirubin metabolites are responsible for the browncoloration of faeces. If bilirubin does not reach the gut,stools become pale in color.Bilirubin in the gut is metabolized by bacteria to producestercobilinogen, which is partly reabsorbed andreexcreted in the urine as urobilinogen. When highlevels of conjugated bilirubin are being excreted , urinemay be a deep orange colour.


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High bil irubin levelHaemolysis (Haemolytic)The increased haemoglobinbreakdown produces bilirubin which overloads the

conjugating mechanism.

Unconjugated hyperbilirubinaemia is commonly

encountered in babies.

Liver disorder (Hepatocellular) Failure of theconjugating mechanism within the hepatocyte.

Obstruction in the biliary system (Cholestatic)including extrahepatic biliary obstruction, Intrahepatic

biliary obstruction is much more difficult to diagnose

than extrahepatic obstruction.


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Jaundice Whats Jaundice?

Jaundice is a yellow discoloration of the skinor sclera.Due to the bil irubin concentration in plasma ismuch greater than normal (greater than about40 mol/L)


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Causes ofjaundice


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Jaundice indicates that there is anelevated concentration of bil irubin inserum.

In neonates it is important to determinethe concentration of unconjugatedbilirubin in order to decide what treatmentis required.

In adults, the most common cause ofjaundice is obstruction, and this isconfirmed by the elevation of both


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Jaundice/More than34.2mol/L(2.0mg/100mL) Latent jaundice/17.2 34.2 mol/L Normal/ Less than 1.70~17.2 mol/L 80% is unconjugated bil irubin and 20%

is conjugated bil irubin

Serumbil irubin


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Because only conjugated bilirubin isexcreted in urine, it is indirect test forincreased concentration of conjugatedbilirubin in serum.

A fresh urine specimen is required sincebilirubin is very unstable when exposed inlight and room temperature.

The chemstrip test for bil irubin in urine.

Urine Bil irubin


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Haemolytic Cholestatic HepatocellularFeatures

1.Bil irubin usually3 upper l imit ofreference range.4.AST, ALT+LDHusually modestly

1.AST+ALT 2.Bil irubin later3.Bil irubin in urine4. ALP later


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DIFFERENTIAL DIAGNOSIS OF JAUNDICEUnconjugated hyperbilirubinemiaIncreased heme catabolismHemolytic anemiaHematoma

Impaired hepatic conjugationNeonatal jaundice

Conjugated hyperbilirubinemiaImpaired hepatic excretionHepatocellular diseasePosthepatic obstruction


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Dye intake and Excretion Indocyanine green retention rate

(ICGR): 15min


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SERUM ENZYMETESTS

AminotransferaseAminotransferase1) AST (Aspartate) and ALT (Alanine) is present in a wide

variety of tissues-including heart, skeletal muscle, kidney,and brain in addition to liver.

2) Serum levels of AST and ALT are elevated to some extent inalmost all liver diseases (viral hepatitis, obstructive jaundiceand liver cirrhosis).

3) The elevations of the enzyme levels do not correlate witheventual outcome, even though they may reflect the extent ofhepatocellular necrosis.


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AminotransferaseminotransferaseClinical value of AST and ALT

The ratio of AST to ALT

Reference Value

AST and ALT: 5~40U/L

SERUM ENZYME TESTS


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MARKERS OF CHOLESTASIS Alkaline phosphatase(ALP)An indices of a blockage of bile flow Cholestasis,which maybe intra- or extra-hepatic disease

(tumor, cirrhosis )

ADULT 25~90U/LADULT 25~90U/LCHILD 50~350U/LCHILD 50~350U/L

SERUM ENZYMETESTS


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Plasma alkaline phosphatase activity as a function of age andsex(men , women). Horizontal lines refer to multiples of the

adult upper reference limit.


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1) The reference range for ALP is dependent on age.

2) In the human body, ALP has been identified in liver,bone, intestine, kidney and leukocytes. ALPs are a

heterogeneous group of enzymes. For patients withhigh ALP levels, measurement of ALP isoenzymes isuseful for differentiating between bone and liversources.

3) The highest elevations of ALP in patients with liverdisease occur in patients with cholestasis or hepaticcarcinoma.

SERUM ENZYMETESTS


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-Glutamyl Transpeptidase ( -GT)Cholestasis

Alcohol

Drugs

Acute hepatic damage

Combining with alkaline phosphatase

Male 11-50U/LFemale 7~32U/L

SERUM ENZYME TESTS


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1) -GT has been localized to the whole hepatobiliary tree-from hepatocytes to common bile duct in the liver, andalso to pancreatic acini and ductules.

2) Serum -GT is elevated in association with a wide varietyof pathologic states in addition to hepatobiliary disease,including chronic alcoholism, pancreatic disease,myocardial infarction, renal failure, chronic obstructivepulmonary disease and diabetes.

3) In liver disease, serum -GT activity correlates wellwith serum ALP, and is the most sensitive indicator ofbiliary tract disease.

SERUM ENZYME TESTS


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5-Nucleotidase (5-NT)

1) 5-NT is present in the intestines, brain, heart, blood

vessels and endocrine pancreas in addition to the liver.

2) Elevation of 5-NT in the serum are purported to be ofhepatobiliary origin only despite the widespread localizationof the enzyme in other body tissues.

3) In clinical hepatic disease, serum 5-NT correlate closely withserum alkaline phosphatase.

4) Serum 5-NT is particularly useful in diagnosing liver diseasein childhood and in pregnancy.

SERUM ENZYMETESTS


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monoamine oxidase, MAO -Proline hydroxylase, PHIndices of hepatic f ibrosis

SERUM ENZYME TESTS


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Unlike some disorders such asacute pancreatit is (Amylase) andmyocardial infarction (MyoglobinTroponin), for which there areenzyme markers that are primari lyused for one disorder and havehigh diagnostic efficiencies, thereare no enzyme markers that arespecif ic for any single l iverdisease.


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When evaluating these disorders,therefore, it is appropriate to consider apanel of markers, sometimes called livefunction tests (LFTs). usually includes bil irubin, AST, ALT, ALP,and sometimes GGT and 5'NT although these tests can reflect various

disease processes in the liver, they donot reflect hepatic reserve for synthesisand metabolic functions


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Other tests for LiverExcretion Function Bile Acids


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Bile Acids The regulation of bile acid is a major function ofthe liver. Cholesterol homeostasis is in large partmaintained by the conversation of cholesterol to bileacids and subsequent regulation of bile acidmetabolism.

Bile acid provides surface-active detergentmolecules that facilitate both hepatic excretion ofcholesterol to bile acids and solubilization of lipids forintestinal absorption.


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The metabolism of bile acid


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The cl inical Signif icancesof SERUM BILE ACIDS1. In the last 20 years, there have been majormethodological advances in the measurement ofserum bile acids.2. Clinical significance:1) Bile acids more specifically reflect excretoryfunction. Increase of bile acids in serum suggestimpaired hepatic uptake or secretion, or portal-systemic shunting2) The high concentration of serum bile acidsseem to occur in viral hepatitis and extrahepaticobstruction.


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SERUM BILE ACIDS3) Abnormal results of ALP, AST and rGT lackedthe specificity of bile acids abnormalities.AST determinations are more sensitive thanthose for fasting serum bile acids in detectingmild liver diseases such as fatty liver orchronic persistent hepatitis, because mild orpatchy hepatocellular injury does not impairhepatic function severely.

4) The ratio of cholic acid to chenodeoxycholicacid is between 0.5-1.0 in healthy subjects,but in extrahepatic obstruction it is increased0.96-3.6.


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SERUM BILE ACIDS Reference value:

Total Bile Acid 0~6mol/L


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Summary of Liver functionests

A request for LFTs will usually generate results forbilirubin, the aminotransferases and alkaline phosphatase.

Raised activities of the aminotransferases(AST and ALT)indicate hepatocellular damage.

Increased bilirubin concentration and increased alkalinephosphatase activity indicate the presence of cholestasis, ablockage in bile flow.

Serial use of LFTs is of most value in following theprogress or resolution of liver disease.

Measurement of GT can give an indication ofhepatocellular enzyme induction due to drugs or alcohol.


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Tests of Viral Hepatit is Hepatitis A

Hepatitis B

Hepatitis C


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Hepatitis A(HAV) is a kind of RNA virus.It is transmitted by the fecal-oral route.

It is thus implicated in most instancesof water-borne and food-transmittedinfection and in epidemics of viral

hepatitis.

Tests of Viral Hepatit is A


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Serologic markers of viralhepatit is AAgent markers definition significances

HAV Anti-HAVIgM type Antibodyto HAV Current or recentinfection of HAV

IgG type Current or previousinfection of HAV,confers immunity


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HBV is a kind of DNA virusconsisted by core and surfacecomponents. HBV transmissionoccurs most commonly via bloodand blood products, contaminatedneedles and intimate personalcontact. HBV is present in al l bodyfluids.

Tests of Viral Hepatit is B


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gent markers definition significances

HBV HBsAG HBV surfaceantigen

Positive in acute or chronic infection

HBeAG e antigen, acomponent

Transiently positive in acute hepatitisB, reflects presence of viral replication

and high infectivityAnti-HBe Antibody to e

antigen

Transiently positive, may be

persistently present in chronic cases,reflects low infectivity

Anti-HBcAntibodyto core

antigen

IgG type Positive in all acute and chronic cases,reliable marker of infection, past orcurrent

IgM type Reflects active viral replication, not

protective

hepatit is


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Agent markers definition significances

Anti-HBs Antibody to

surface

confers immunity,


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Tests of Viral Hepatit is C HCV is a kind of RNA virus and issimilar to HBV, is largely parenterallytransmitted. HCV is the main causeof post-transfusion hepatitis.


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Serologic markers of viralhepatit is

Agent markers definition significances

HCV Anti-HCV Antibody

to HCV

Positive after clinical

onset(15 weeks),

Not protective,

Persists in chronic infection


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Liver Disease


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PoisoningInfection Viral hepatitis (hepatitis B)Inadequate perfusionChronic excess alcohol ingestionAutoimmune diseaseUnusual cause of cirrhosis:1-antitrypsin deficient and Wilsons

disease

Causes for l iver disease


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Liver diseaseAcute Hepatocellular InjuryViral Hepatitis

Acute Liver failure

Cholestatic Liver DiseaseIntrahepatic ObstructionExtrahepatic Obstruction

Chronic Liver DiseaseChronic Hepatitis

Cirrhosis

Liver Cancer

Alcoholic Liver DiseaseFatty Liver

Alcoholic He atitis


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It may resolve

It may progress to acute hepatic failureIt may lead to chronic hepatic damage

OUTCOME

Acute Hepatocellular Injury


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Biochemicalfindings inhepaticfailure


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Cholestasis Cholestasis represents the demonstrableaccumulation in the blood stream of

substances normally excreted in bile(e.g., bil irubin, cholesterol, bile acids).


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Cholestatic Liver Disease Intrahepatic Obstruction

Intrahepatic cholestasis often results

from cirrhosis or hepatitis. Extrahepatic Obstruction

Extrahepatic cholestasis is usually the

result of mechanical obstruction of thecommon bile duct or hepatic duct.


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Chronic Liver Disease

Chronic Hepatitis chronic active hepatitis

chronic persistent hepatitis Cirrhosis

Liver enzyme levels in cirrhosis are variably elevatedand can be normal during the terminal stages of thedisease.

Primary biliary cirrhosis /Elevations in ALP andaminotransferases are expected along with high titers

of antimitochondrial antibody. Liver Cancer

The liver enzyme results tend to be more elevated inthe active form; however, differentiation is best made

by performing a liver biopsy.


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Fibrosis of Liver tissuesFibrosis is common to several chronic liverdiseases and as such is the leading causeof morbidity and mortality from hepaticdisease.Hepatic fibrosis may have biologic effectson cells as well as physical effects on bloodflow and is a main cause of portalhypertension.


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The most common causes of cirrhosis are chronicexcess alcohol ingestion, viral hepatitis andautoimmune diseases.Cirrhosis is not reversible. There are no goodbiochemical indicators of cirrhosis in the early andstable periodCirrhosis can develop in children as a result of a1-antitrypsin deficiency or Wilsons disease and inadult due to haemochromatosis.

Cirrhosis


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Terminal stage ofcirrhosis

Developing jaundiceEncephalopathyAscitesBleeding tendenicesTerminal l iver failure


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Alcoholic Liver DiseaseFatty LiverThe concentrations of traditional liver enzymesare typically within the normal range.Definitive diagnosis is made by a liver biopsy.The disease is considered benign and can beeffectively reversed by immediate abstinence

from ethanol intake.Alcoholic Hepatitis Liver enzyme concentrations are increased,

notably AST and ALT


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Normal Liver


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Fatty Liver


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Cirrhotic Liver


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A 49-year-old woman attend her GP with an 8-day history ofanorexia, nausea and flu-like symptom. She had noticed thather urine had been dark in colour over the past 2 days.Physical examination revealed tenderness in the right upperquadrant of the abdomen. LFTS were as follows:

Bilirubin AST ALT ALP -GT TP Albmol/L U/L(g/L)63 936 2700 410 312 68 42

Comment on these results.

What is the differential diagnosis?

Case history


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Markers For Liver Function And Disease


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Markers For Liver Function And Disease

Disease or function MarkersFunction evaluationNormal synthesis capacity Albumin, prealbumin prothrombin time,Excretory function Bil irubin, bile acids , globulinsMetabolic function Ammonia, amino acids, l ipids, serum

protein electrophoresisPathological evaluationHepatocel lular injury AST, ALTObstruction Bil irubin, alkaline phosphatase, -

GT , 5 - nucleotidosebile acids,InfectionsViral and autoimmune serologies


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ALT and AST in acute l iver injurydisease enzyme marker

acute hepatitis ALT and AST elevated>1000U/L (viral or toxic)

HAV ALT elevated in 3 to 4 weeks after infectionALT return to normal within 8 to 12 weeks

HBV preclinical incubation phase is longer and ALTand and AST may remain normal for 2 to 6monthsHCV ALT and AST return to normal within 2 to 3months

chronic activehepatitis ALT and AST elevated 5 to10 fold

end-stage ALT and AST return to normal or subnormalliver disease


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Relationship of AST and ALT toALP and GGT in Hepatit is


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Relationship of AST and ALT to ALPand GGT in Cholestasis

Multi

pli


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The best markers for intrahepatic andextrahepatic cholestas is are ALP, GGT, and 5'NT AST and ALT are generally only sl ightly elevated incholestasis, rarely more than 500 U/L. The largest elevations (four- to 10-fold) of ALP are

typically seen in obstruction owing to gallstones ormalignancy and in biliary cirrhosis . Measurement of total and direct bilirubin

are also important in making the diagnosisof obstructive jaundice.


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Ratio (AST/ALT)


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The Ratio of (AST/ALT) Further differentiation of specific liver

diseases is aided by calculating the ratioof AST to ALT levels. acute or chronic ? intra- or extrahepatic ?

recommended by the International Federation ofClinical Chemistry (IFCC) The ratio is normally approximately 1.15

ALT versus AST levels


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in various l iver diseases


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AST/ALTDiseaseST/ALT

Acute disorders of the liver 1.0alcoholic liver diseasechronic active hepatitisChronic persistent hepatitis normal

Extrahepatic obstructionacute passage of a stone 1.5intrahepatic cholestasisbiliary cirrhosis and malignancy 1.5

Relationship of AST and ALT to ALP


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and GGT in Malignancy

Mu

ltiplies

o

Relationship of AST and ALT to ALP an


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GGT in Alcoholic Live Disease

Mu

ltiplie

s


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Abnormal Liver Function TestsHepatocellular Disease Cholestatic Disease

NormalAlbumin DecreasedAlbumin NormalAlbumin DecreasedAlbuminAcuteHepatitis ChronicHepatitis AcuteCholestasis ChronicCholestasis

UltrasoundDetectionIntrahepatic Cholestasis Extrahepatic Cholestasi


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Case historyA 60-years-old female with a history of breast carcinomatreated by mastectomy three years previously is nowcomplaining of general malaise and bone pain. Biochemistryshowed that fluid and electrolyte, total protein, albuminand calcium values were all normal. LFTs were as follows:Bilirubin AST ALT Alkaline phosphatase GTmol/l U/l

7 33 38 89032Evaluate these results and suggest a likely diagnosis.


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Biochemical monitoring of liver disease is bysequential measurements of the aminotransferase,bilirubin and alkaline phosphatase. In acute liver damage there is usually intrahepaticobstruction as well as hepatocellular damage. Severe cases of acute liver damage may progressto hepatocellalur failure. Cirrhosis is the end point of both acute and chronicliver damage, as well as being caused by a numberof metabolic and autoimmune diseases. Biochemical tests may be of little value in makinga specific diagnosis. A liver biopsy is frequentlymore helpful.

Summary


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The clinical significances of each liverfunction test?

The differentiation diagnosis ofjaundice.

The evaluations of biochemical tests of

liver functions in different liverdiseases.


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Thank You for YourAttention!

23172860 Liver Function

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