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Liver function test


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Liver function test

  2. 2.  A clinician noticed pallor & icterus on a 12 year old boy who came to OPD. General physical examination revealed the boy was poorly built and nourished. On abdominal examination, boy had spleenomegaly with ulcers around ankle. What is your probable diagnosis? Suggest the biochemical investigations to confirm your diagnosis. 2
  3. 3. Classification – Liver Function Test Based on Liver Function & Clinical UtilityGroup I Markers of liver Serum bilirubin – Total and dysfunction Conjugated Urine – Bile salts, Bile pigments, UrobilinogenGroup II Synthetic function Total protein, Albumin and A/G ratio Prothrombin time Serum CholesterolGroup III Markers of hepatocellular Alanine transaminase (ALT) injury Aspartate transaminase (AST)Group IV Markers of obstructive Alkaline phosphatase liver disease Gamma glutamyl transferaseGroup V Metabolic capacity Blood ammonia Galactose tolerance testGroup VI Excretory & Detoxifying Bromsulfthalein excretory test capacity Hippuric acid test 3
  4. 4. Tests based on Excretory capacity of liver Bromsulpthalein (BSP) test Dye used to assess excretory function of the liver Non-toxic compound exclusively excreted through bile Dose: 5mg/Kg body weight Administration: Intravenously Procedure: Serum concentration is measured at 45 min and at 2 hours Result: > 5% of dye retained → abnormality in excretory function of the liver 4
  5. 5. Tests based on Detoxifying capacity of liver Hippuric acid test Hippuric acid synthesis → assess detoxification function Benzoic acid + Glycine = Hippuric acid Procedure: - 6g sodium benzoate dissolved in 250ml water is given orally 2hrs after light breakfast and after emptying bladder - Urine is collected for next 4 hours - Amount of hippuric acid excreted is estimated - Normal: > 4.5 g of hippuric acid (60% of sodium benzoate) - Abnormal: < 3g indicates hepatic dysfunction 5
  6. 6. Serum Bilirubin Excretory product Formation: Catabolism of heme Types: - Unconjugated: water insoluble - Conjugated: water soluble Estimation: ‘van den Bergh’ reaction Reagents: - Diazotised sulfanilic acid: Sulfanilic acid in hydrochloric acid + sodium nitrite - Methanol 6
  7. 7. Serum Bilirubin – Estimation Principle: When diazotised sulfanilic acid reacts with bilirubin, it forms ‘azobilirubin’, a purple coloured product ↑ Conjugated bilirubin → gives colour immediately → ‘Direct positive’ ↑ Unconjugated bilirubin → gives colour only after addition of methanol → ‘Indirect positive’ ↑ Both conjugated and unconjugated → ‘Biphasic’ 7
  8. 8. Serum Bilirubin – ApplicationsType of van den Class of CausesBilirubin Bergh Jaundice ReactionUnconjugated Indirect positive Pre-hepatic or Neonatal jaundice Hemolytic Sickle cell anaemia Thalassemia Gilbert’s syndrome Crigler-Najjar syndrome Mismatch blood transfusionBoth Biphasic Hepatic Viral hepatitisUnconjugated Alcoholic hepatitisand Conjugated Drug induced hepatitisConjugated Direct positive Post-hepatic or Gall stones Obstructive Biliary atresia Tumours of biliary tract Carcinoma head of pancreas 8
  9. 9. Urine – Urobilinogen Ehrlich’s test Principle: Urobilinogen reacts with p- dimethylamino-benzaldehyde in chloroform to form a pink coloured aldehyde complex. Reagents: - Ehrlich’s reagent - Saturate sodium acetate - Chloroform 9
  10. 10. Urine – Urobilinogen Procedure: 5 ml Urine + 5 ml Ehrlich’s reagent → Mix and allow to stand for 10 min → + 5 ml saturated sodium acetate and mix → + 5 ml chloroform → shake vigourously and allow layers to separate Appearance of pink colour in the chloroform layer indicates presence of urobilinogen Colour is easily detected when viewed from top of the test tube 10
  11. 11. Urine – Bile salts & Bile pigments Bile salts: Hay’s test Principle: Bile salts have the property of lowering surface tension. Hence when sulphur poweder is sprinkled to urine containing bile salts, it sinks to the bottom. Bile pigments: Fouchet’s test Principle: Bile pigments adhare to the precipitate of barium sulphate. On addition of Fouchet’s reagent, ferric chloride in the presence of trichloroacetic acid oxidises yellow colour bilirubin to green colour biliverdin. 11
  12. 12.  A 45 year female patient was admitted to casualty with the complaints of severe pain in the right hypocondriac region, decreased appetite and vomiting. She also complained of pruritis. General physical examination revealed that the female was obese. Per abdomen examination showed tenderness in right hypochondriac region. What is your probable diagnosis? Suggest the biochemical investigations to confirm your diagnosis. 12
  13. 13. Urinary findings in Jaundice Type of Urobilinogen Bile salts Bile pigments JaundicePre-hepatic or +++ NIL NILHemolyticHepatic Normal / ↓ + ++Post-hepatic of NIL +++ ++++Obstructive 13
  14. 14. Tests based on synthetic function Seum total proteins: estimated by ‘Biuret method’ Serum alboumin: estimated by BCG-dye binding method Total proteins – Albumin = Globulin Calculation of Albumin/Globulin ratio Prothrombin Time - ½ life of prothrombin is 6 hours - indicates present functioning status of liver Serum cholesterol: estimation by ‘cholesterol oxidase’ method 14
  15. 15. Application of tests based on synthetic functions of liver - ↓ Serum albumin levels - ↓ Serum total protein levels - Reversal of A/G ratio - ↓ Serum total cholesterol levels - Prolonged prothrombin time Chronic diseases of liver and in cirrhosis of liver 15
  16. 16. Enzymes indicating Hepatocellular damage and Obstructive liver diseaseName of Enzyme Diseases associated with increaseAlanine transaminase (ALT) Acute viral hepatitisAspartate transaminase (AST) Alcoholic liver disease Autoimmune hepatitis Chronic viral hepatitis Non-alcoholic steatohepatitisAlkaline Phosphatase Cholestatic jaundice Hepatic carcinoma Gall stones Biliary atresia Tumours of Biliary tract Carcinoma head of the pancreasGamma Glutamyl transferase Chronic alcoholism5’ Nucleotidase Biliary obstruction 16
  17. 17. Tests based on Metabolic capacity of liver Blood Ammonia levels Index of urea synthesis by the liver Sample: Arterial blood Accumulation of ammonia → ↑ levels in CNS → coma Use: Hepatic encephalopathy Galactose tolerance test 17
  18. 18. Liver Function Test - SummaryEstimation of serum bilirubin van den Bergh reaction↑Conjugated bilirubin , ↑ alkaline Obstructive jaundicephosphatasewith bile salts and bile pigmentsEstimation of urobilinogen Ehrlich’s test↑ Urobilinogen Hemolytic jaundiceMarkers of Hepatocellular damage ALT & ASTMarker of alcoholic liver disease Gamma glutamyl transferaseTests to detect synthetic functions of liver Serum albumin Prothrombin timeTest to assess excretory function of liver Bromsulphthalein TestTest to assess detoxification function of liver Hippuric acid test↑ Blood ammonia levels Hepatic encephalopathy 18
  19. 19. Examination Tips• Classify liver function tests. Describe any three tests with its clinical importance.• van den Bergh reaction• Test based on synthetic functions of the liver• Enzyme markers for liver disease• Ehrlich’s test• Bromsulpthalein test• Hippuric acid test 19
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