LIVER FUNCTION TESTS AND LIVER DISEASES. Prof. Fang Zheng Department of Laboratory Medicine School of Medicine, Wuhan University

Transcription

1 LIVER FUNCTION TESTS AND LIVER DISEASES Prof. Fang Zheng Department of Laboratory Medicine School of Medicine, Wuhan University

2 Content the Anatomy of Liver the Function of Liver Tests of Liver Function Liver Diseases How to use biochemical tests of liver functions?

3 INTRODUCTION The liver is divided into four lobes.

4 THE STRUCTURE OF LIVER

5 LOBES VASCULAR AND BILIARY SYSTEMS The portal vein carries blood that has already passed through the capillary bed of the gastrointestinal tract. The hepatic artery carries well-oxygenated blood to the liver. Both circulations mix in a vast network of hepatic sinusoids and leave the live via the hepatic vein. Sinusoids are lined by endothelial and Kupffer s cells.

6 LOBES VASCULAR AND BILIARY SYSTEMS In the liver the ductules merge into bile ducts, hepatic ducts, and eventually the common hepatic ducts. Their bile drains into the right and left hepatic ducts.

7 Liver Function 1. Synthesis secretion plasma proteins, bile 2. Metabolism of carbohydrate lipid, protein vitamins, hormone bile acids, bile pigment, drug and toxins 3. Detoxification (biotransformation)

8 TESTS OF LIVER FUNCTION 1.Tests of Protein Metabolism 2. Tests of Bilirublin Metabolism 3. Dye intake and Excretion 4. Biochemical Serum Enzyme Tests 5. Tests of Viral Hepatitis 6. Other tests

9 Tests of Protein Metabolism 1. Serum total protein (TP), albumin (A) and globulin (G) 2. Serum protein electrophoresis 3. Hepatic neoplasm markers

10 Serum total protein (TP), albumin (A) and globulin (G) Albumin Albumin is quantitatively the most important plasma protein synthesized by the liver and thus is a useful indicator of hepatic function. Serum albumin levels are depressed in alcoholic cirrhosis. A crude measure of the liver s synthetic capacity hypoalbuminaemia: advanced chronic liver disease severe acute liver damage

11 Serum total protein (TP), albumin (A) and globulin (G) Globulin: The main proteins in serum. Total serum globin: the severity of liver disease

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

13 Serum protein electrophoresis Densitometric scan of a normal serum protein electrophoresis pattern showing the relative position of the albumin,α1,α2,β and γregions

14 Hepatic neoplasm markers alpha-fetoprotein(afp): primary hepatocellular carcinoma Carcinoembryonic antigen(cea): liver metastatic carcinoma or other carcinomas of the gastrointestinal system.

15 Reference Value (AFP) Normal 25ng/mL Hepatitis 25~200ng/mL carcinoma >400ng/mL

16 OTHER SERUM PROTEINS PRODUCED 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 liver s ability to synthesize these proteins can result in clotting abnormalities 2) Prolongation of the prothrombin time is not specific for liver disease.

17 Tests of Bilirublin Metabolism Serum total bilirubin(stb) Conjugated bilirubin Urobilinogen Stercobilinogen

18 Bilirubin Metabolism 1) Bilirubin is the principal degradation product of heme. 2) Bilirubin transport and conjugation in the hepatocyte. 3) The generally accepted reference range for normal plasma bilirubin concentrations in healthy persons, which includes 95 per cent of all individuals values, is 1.7 to 17.1umol/L.

19 Bilirubin metabolism

20 Bilirubin Bilirubin is derived from haemoglobin and the cytochrome. It is normally conjugated with glucuronic acid. Both conjugated bilirubin and unconjugated bilirubin may be present in plasma. Conjugated bilirubin is water soluble, unconjugated bilirubin is not, and binds to albumin. Bilirubin is neurotoxic, and if its levels rise too high in neonates, permanent brain damage can occur.

21 BILIRUBIN Bilirubin metabolites are responsible for the brown coloration of faeces. Bilirubin in the gut is metabolized by bacteria to produce stercobilinogen, which is partly reabsorbed and reexcreted in the urine as urobilinogen. When high levels of conjugated bilirubin are being excreted, urine may be a deep orange colour.

22 High bilirubin level Haemolysis (Haemolytic)The increased haemoglobin breakdown produces bilirubin which overloads the conjugating mechanism. Unconjugated hyperbilirubinaemia is commonly encountered in babies. Liver disorder (Hepatocellular) Failure of the conjugating 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.

23 Jaundice What s Jaundice? Jaundice is a yellow discoloration of the skin or sclera. Due to the bilirubin concentration in plasma is much greater than normal (greater than about 34 mol/l)

24 Causes of jaundice

25 Jaundice indicates that there is an elevated concentration of bilirubin in serum. In neonates it is important to determine the concentration of unconjugated bilirubin. In adults, the most common cause of jaundice is obstruction, and this is confirmed by the elevation of both bilirubin and alkaline phosphatase

26 Serum bilirubin Jaundice/More than 34.2 mol/l(2.0mg/100ml) Latent jaundice /17.2~34.2 mol/l Normal/ Less than 1.70~17.2 mol/l 80% is unconjugated bilirubin and 20% is conjugated bilirubin

27 Urine Bilirubin Because only conjugated bilirubin is excreted in urine, it is indirect test for increased concentration of conjugated bilirubin in serum. A fresh urine specimen is required since bilirubin is very unstable when exposed in light and room temperature. The chemstrip test for bilirubin in urine.

28 Haemolytic Cholestatic Hepatocellular Featur es 1.Bilirubin usually< 75 mol/l. 2.No bilirubin in urine. 3.Reticulocytosis 4.haemoglobin 5. haptoglobin ( 触 珠 蛋 白 ) 1.Bilirubin maybe 2.Bilirubin in urine 3.ALP Usually>3 upper limit of reference range. 4.AST, ALT+LDH usually modestly 1.AST+ALT 2.Bilirubin later 3.Bilirubin in urine 4. ALP later 6. LDH may

29 indicators Normal Haemolytic Hepatocellular Cholestatic Serum Bilirubin Total Bilirubin Conjugated Bilirubin Unconjugated Bilirubin Urine Bilirubin Urobilinogen Little variable Urobilin little variable feces Normal Dark Pale or Normal pale Stercobilinogen Normal - or

30 DIFFEERENTIAL DIANNOSIS OF JAUNDICE Unconjugated hyperbilirubinemia Increased heme catabolism Hemolytic anemia Hematoma Impaired hepatic conjugation Neonatal jaundice Conjugated hyperbilirubinemia Impaired hepatic excretion Hepatocellular disease Posthepatic obstruction

31 Dye intake and Excretion Indocyanine green retention rate (ICGR): 15min<10% Chronic hepatitis: 15-20% Cirrhosis: 35%

32 SERUM ENZYME TESTS Aminotransferase 1) AST and ALT is present in a wide variety of tissuesincluding heart, skeletal muscle, kidney, and brain in addition to liver. 2) Serum levels of AST and ALT are elevated to some extent in almost all liver diseases (viral hepatitis, obstructive jaundice and liver cirrhosis). 3) The elevations of the enzyme levels do not correlate with eventual outcome, even though they may reflect the extent of hepatocellular necrosis.

33 SERUM ENZYME TESTS Aminotransferase Clinical value of AST and ALT The ratio of AST to ALT Reference Value AST and ALT: 5~40U/L

34 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/L CHILD 50~350U/L SERUM ENZYME TESTS

35 Plasma alkaline phosphatase activity as a function of age and sex( men;, women). Horizontal lines refer to multiples of the adult upper reference limit.

36 SERUM ENZYME TESTS 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 with high ALP levels. 3) The highest elevations of ALP in patients with liver disease occur in patients with cholestasis or hepatic carcinoma.

37 SERUM ENZYME TESTS -Glutamyl Transpeptidase ( -GT) Cholestasis Alcohol Drugs Acute hepatic damage Combining with alkaline phosphatase Male 11-50U/L Female 7~32U/L

38 SERUM ENZYME TESTS 1) -GT has been localized to the whole hepatobiliary treefrom hepatocytes to common bile duct in the liver, and also to pancreatic acini and ductules. 2) Serum -GT is elevated in association with a wide variety of pathologic states in addition to hepatobiliary disease, including chronic alcoholism, pancreatic disease, myocardial infarction, renal failure, chronic obstructive pulmonary disease and diabetes. 3) In liver disease, serum -GT activity correlates well with serum ALP, and is the most sensitive indicator of biliary tract disease.

39 SERUM ENZYME TESTS 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 of hepatobiliary origin only despite the widespread localization of the enzyme in other body tissues. 3) In clinical hepatic disease, serum 5 -NT correlate closely with serum alkaline phosphatase. 4) Serum 5 -NT is particularly useful in diagnosing liver disease in childhood and in pregnancy.

40 SERUM ENZYME TESTS monoamine oxidase, MAO Β-Proline hydroxylase, PH Indices of hepatic fibrosis

41 Unlike some disorders such as acute pancreatitis (Amylase) and myocardial infarction (Myoglobin Troponin) There are enzyme markers that are primarily used for one disorder and have high diagnostic efficiencies, there are no enzyme markers that are specific for any single liver disease.

42 When evaluating these disorders, therefore, it is appropriate to consider a panel of markers, sometimes called live function tests (LFTs). usually includes bilirubin, AST, ALT, ALP, and sometimes GGT and 5'NT. although these tests can reflect various disease processes in the liver, they do not reflect hepatic reserve for synthesis and metabolic functions.

43 Other tests for Liver Excretion Function Bile Acids

44 Bile Acids The regulation of bile acid is a major function of the liver. Cholesterol homeostasis is in large part maintained by the conversation of cholesterol to bile acids. Bile acid provides surface-active detergent molecules ( excretion of cholesterol and solubilization of lipids).

45 The metabolism of bile acid

46

47 The clinical Significances of SERUM BILE ACIDS 1. In the last 20 years, there have been major methodological advances. 2. Clinical significance: 1) Bile acids more specifically reflect excretory function. (impaired hepatic uptake or secretion, or portal- systemic shunting) 2) The high concentration of serum bile acids seem to occur in viral hepatitis and extrahepatic obstruction.

48 SERUM BILE ACIDS 3) Abnormal results of ALP, AST and rgt lacked the specificity of bile acids abnormalities. (AST are more sensitive than those for fasting serum bile acids) 4) The ratio of cholic acid to chenodeoxycholic acid is between in healthy subjects, but in extrahepatic obstruction it is increased

49 SERUM BILE ACIDS Reference value: Total Bile Acid: 0~6 mol/l

50 Summary of Liver function tests A request for LFTs will usually generate results for bilirubin, the aminotransferases and alkaline phosphatase. Raised activities of the aminotransferases(ast and ALT) indicate hepatocellular damage. Increased bilirubin concentration and increased alkaline phosphatase activity indicate the presence of cholestasis, a blockage in bile flow. Serial use of LFTs is of most value in following the progress or resolution of liver disease. Measurement of GT can give an indication of hepatocellular enzyme induction due to drugs or alcohol.

51 Tests of Viral Hepatitis Hepatitis A Hepatitis B Hepatitis C

52 Tests of Viral Hepatitis A Hepatitis A(HAV) is a kind of RNA virus. It is transmitted by the fecal-oral route. It is thus implicated in most instances of water-borne and food-transmitted infection and in epidemics of viral hepatitis.

53 Serologic markers of viral hepatitis A Agent markers definition significances HAV Anti- HAV Antibody to HAV Current or recent infection of HAV IgM type IgG type Current or previous infection of HAV, confers immunity

54 Tests of Viral Hepatitis B HBV is a kind of DNA virus consisted by core and surface components. HBV transmission occurs most commonly via blood and blood products, contaminated needles and intimate personal contact. HBV is present in all body fluids.

55 Serologic markers of viral hepatitis Agent markers definition significances HBV HBsAG HBV surface antigen HBeAG Anti-HBe Anti-HBc Antibody to core antigen e antigen, a component Antibody to e antigen IgG type IgM type Positive in acute or chronic infection Transiently positive in acute hepatitis B, reflects presence of viral replication and high infectivity Transiently positive, may be persistently present in chronic cases, reflects low infectivity Positive in all acute and chronic cases reliable marker of infection, past or current Reflects active viral replication, not protective

56 Agent markers definition significances Anti-HBs Antibody to surface confers immunity,

57 Tests of Viral Hepatitis C HCV is a kind of RNA virus and is similar to HBV, is largely parenterally transmitted. HCV is the main cause of posttransfusion hepatitis.

58 Serologic markers of viral hepatitis Agent markers definition significances HCV Anti- HCV Antibody to HCV Positive after clinical onset(15 weeks), Not protective, Persists in chronic infection

59 Liver Disease

60 Causes for liver disease Poisoning Infection Viral hepatitis (hepatitis B) Inadequate perfusion Chronic excess alcohol ingestion Autoimmune disease Unusual cause of cirrhosis: 1-antitrypsin deficient and Wilson s disease

61 Liver disease Acute Hepatocellular Injury Viral Hepatitis Acute Liver failure Cholestatic Liver Disease Intrahepatic Obstruction Extrahepatic Obstruction Chronic Liver Disease Chronic Hepatitis Cirrhosis Liver Cancer Alcoholic Liver Disease Fatty Liver Alcoholic Hepatitis

62 Acute Hepatocellular Injury OUTCOME It may resolve It may progress to acute hepatic failure It may lead to chronic hepatic damage

63 Biochemical findings in hepatic failure

64 Cholestasis Cholestasis represents the demonstrable accumulation in the blood stream of substances normally excreted in bile (e.g., bilirubin, cholesterol, bile acids).

65 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 the common bile duct or hepatic duct.

66 Chronic Liver Disease Chronic Hepatitis chronic active hepatitis chronic persistent hepatitis Cirrhosis Liver enzyme levels in cirrhosis are variably elevated and can be normal during the terminal stages of the disease. Primary biliary cirrhosis /Elevations in ALP and aminotransferases are expected along with high titers of antimitochondrial antibody. Liver Cancer The liver enzyme results tend to be more elevated in the active form; however, differentiation is best made by performing a liver biopsy.

67 Fibrosis of Liver tissues Fibrosis is common to several chronic liver diseases and as such is the leading cause of morbidity and mortality from hepatic disease. Hepatic fibrosis may have biologic effects on cells as well as physical effects on blood flow and is a main cause of portal hypertension.

68 Cirrhosis The most common causes of cirrhosis are chronic excess alcohol ingestion, viral hepatitis and autoimmune diseases. Cirrhosis is not reversible. There are no good biochemical indicators of cirrhosis in the early and stable period Cirrhosis can develop in children as a result of a1- antitrypsin deficiency or Wilson s disease and in adult due to haemochromatosis.

69 Terminal stage of cirrhosis Developing jaundice Encephalopathy Ascites Bleeding tendenices Terminal liver failure

70 Alcoholic Liver Disease Fatty Liver The concentrations of traditional liver enzymes are typically within the normal range. Definitive diagnosis is made by a liver biopsy. The disease is considered benign and can be effectively reversed by immediate abstinence from ethanol intake. Alcoholic Hepatitis Liver enzyme concentrations are increased, notably AST and ALT

71 Normal Liver

72 Fatty Liver

73 Cirrhotic Liver

74 Case history A 49-year-old woman attend her GP with an 8-day history of anorexia, nausea and flu-like symptom. She had noticed that her urine had been dark in colour over the past 2 days. Physical examination revealed tenderness in the right upper quadrant of the abdomen. LFTS were as follows: Bilirubin AST ALT ALP -GT TP Alb mol/l U/L (g/l) Comment on these results. What is the differential diagnosis?

75 Markers For Liver Function And Disease

76 Markers For Liver Function And Disease Disease or function Markers Function evaluation Normal synthesis capacity Albumin, prealbumin prothrombin time, Excretory function Bilirubin, bile acids, globulins Metabolic function Ammonia, amino acids, lipids, serum protein electrophoresis Pathological evaluation Hepatocellular injury AST, ALT Obstruction Bilirubin, alkaline phosphatase, γ- GT, 5 - nucleotidose bile acids, Infections Viral and autoimmune serologies Malignancies CEA, α-fetoprotein

77 ALT and AST in acute liver injury disease enzyme marker acute hepatitis (viral or toxic) HAV HBV and HCV chronic active hepatitis ALT and AST elevated>1000u/l ALT elevated in 3 to 4 weeks after infection ALT return to normal within 8 to 12 weeks preclinical incubation phase is longer and ALT and AST may remain normal for 2 to 6months ALT and AST return to normal within 2 to 3months ALT and AST elevated 5 to10 fold end-stage liver disease ALT and AST return to normal or subnormal

78 Relationship of AST and ALT to ALP and GGT in Hepatitis

79 Relationship of AST and ALT to ALP and GGT in Cholestasis Multiplies of normal

80 The best markers for intrahepatic and extrahepatic cholestasis are ALP, GGT, and 5'NT AST and ALT are generally only slightly elevated in cholestasis, rarely more than 500 U/L. The largest elevations (four- to 10-fold) of ALP are typically seen in obstruction owing to gallstones or malignancy and in biliary cirrhosis. Measurement of total and direct bilirubin are also important in making the diagnosis of obstructive jaundice.

81 Ratio (AST/ALT)

82 The Ratio of (AST/ALT) Further differentiation of specific liver diseases is aided by calculating the ratio of AST to ALT levels. acute or chronic? intra- or extrahepatic? recommended by the International Federation of Clinical Chemistry (IFCC) The ratio is normally approximately 1.15

83 ALT versus AST levels in various liver diseases

84 Disease AST/ALT AST/ALT Acute disorders of the liver <1.0 acute hepatitis Chronic disorders of the liver >1.0 alcoholic liver disease chronic active hepatitis Chronic persistent hepatitis normal Extrahepatic obstruction acute passage of a stone <1.5 intrahepatic cholestasis biliary cirrhosis and malignancy 1.5

85 Multiplies of normal Relationship of AST and ALT to ALP and GGT in Malignancy

86 Multiplies of normal Relationship of AST and ALT to ALP and GGT in Alcoholic Live Disease

87 Abnormal Liver Function Tests Hepatocellular Disease Normal Albumin Acute Hepatitis Decreased Albumin Chronic Hepatitis Cholestatic Disease Normal Albumin Acute Cholestasis Decreased Albumin Chronic Cholestasis Ultrasound Detection Intrahepatic Cholestasis Extrahepatic Cholestasis

88 Case history A 60-years-old female with a history of breast carcinoma treated by mastectomy three years previously is now complaining of general malaise and bone pain. Biochemistry showed that fluid and electrolyte, total protein, albumin and calcium values were all normal. LFTs were as follows: Bilirubin AST ALT Alkaline phosphatase GT mol/l U/l Evaluate these results and suggest a likely diagnosis.

89 Summary Biochemical monitoring of liver disease is by sequential measurements of the aminotransferase, bilirubin and alkaline phosphatase. In acute liver damage there is usually intrahepatic obstruction as well as hepatocellular damage. Severe cases of acute liver damage may progress to hepatocellalur failure. Cirrhosis is the end point of both acute and chronic liver damage, as well as being caused by a number of metabolic and autoimmune diseases. Biochemical tests may be of little value in making a specific diagnosis. A liver biopsy is frequently more helpful.

90 The clinical significances of each liver function test? The differentiation diagnosis of jaundice. The evaluations of biochemical tests of liver functions in different liver diseases.

91 Thank You for Your Attention!