JANET LIM-DY, M.D., F,P.S.P. D.T.M.H.

1. JANET LIM-DY, M.D., F,P.S.P. D.T.M.H.

2. EVALUATION OF LIVER FUNCTION TESTS

3. Overview 3 Systems involved in understanding liver function tests: Hepatocyte • Proteins synthesis • Coagulation factors • synthesis Biliary Tract: bili metabolism RES: Immune sys. , Heme & globin metabolites

4. KREBS CYCLE FA SYNTHESIS & BREAKDOWN LIPOPROTEIN METABOLISM AA & NUCLEIC ACID METABOLISM GLUCONEOGENESIS GLYCOLYSIS HMP-SHUNT 2 GENERAL METABOLIC PATHWAYS: • AA-CHO PATHWAY • involves ALT & AST • 2. UREA CYCLE • NH4 urea • Enzyme OCT unique to liver

5. LIVER FUNCTION TESTS hepatic structure, cell integrity, function

6. LIVER FUNCTION TESTS Reasons for requesting LFT: • For Diagnosis • For Differentiation Is Hepatic damage due to primary hepatocyte damage or biliary system obstruction? • Prognosis / Monitoring

7. TESTS FOR DISCLOSING HEPATIC DYSFUNCTION Liver Enzymes • Aminotransferases (ALT and AST) • Lactate Dehydrogenase (LDH) • Alkaline Phosphatase (Alk Phos) •  Glutamyl transferase (GGT)

8. TESTS FOR DISCLOSING HEPATIC DYSFUNCTION Total Protein Albumin • Gamma Globulins • Alpha Globulins Clotting Factors ProthrombinTime HEPATOBILIARY DYSFUNCTION • Serum Bilirubin ( total & direct)

9. PATIENT PREPARATION & SPECIMEN COLLECTION • No special preparation required • Serum : Preferred Specimen • Heparinized Plasma : Acceptable

10. Liver Enzymes: Transaminases • 2 major aminotransferases • AST(SGOT) – Aspartate transferase • ALT(SGPT) – Alanine transferase • Catalyze reversibly the transfer of an amino gr.of either AST or ALT to alpha-ketoglutarate to yield glutamate plus the corresponding ketoacid of the starting a.a.

11. Liver Enzymes: Transaminases Reaction catalyzed by ALT COOH CH3 COOH COOH | + | B6 | | CH2 H C- CH2 C=O | | | | CH2+ COOH CH2+ COOH | | pyruvate C=OC- | | COOH COOH -ketoglutarate L-alanine L-glutamate NH3 NH3

12. Transaminases Distribution: ALT: liver (1o location) kidney & muscle (lesser quantity) more liver-specific cytoplasmic enzyme AST : in many body tissues, ex heart,liver,muscle,RBC brain,lung ,pancreas & kidney. cytoplasmic & mitochon drial enzyme Elevation of ALT activity persist longer AST AST ALT

13. Reference value ALT : Males 10-40 U/L Females 7-35 U/L AST : Males 15-40 U/L Females 13-35 U/L

14. Transaminases In Hepatobiliary Diseases Hepatocellular injury AST Cytoplasmic AST & ALT released into serum Mild: PM damaged AST ALT ALT Mitochondrial AST released into serum: Disproportionate elevation---- (De Ritis quotient) More severe: Mitochondrial membrane damaged AST 80%

15. AST/ALT (DeRitis) ratio: to discriminate alcoholic hepatitis vs other liver diseases ; Sometimes help determine whether the liver is damaged or another organ has been damage • How to calculate AST/ALT ratio? ex. AST= 52, ALT =67 52/67 = .75 • AST / ALT > 2 ( 3:1 to 4:1) = ALD • AST/ALT <1,most likely assoc. with other cause eg. Viral hep

16. Transaminases • acute hepatitis : ALT is more increased than AST (20 -100 x the upper limit) • AST is 10x the upper limit • 5-10x the upper limit in liver Ca • Cirrhosis : ALT is more increased than AST, but as fibrosis progresses, ALTdec. In end stage = both enzymes are dec. • Acute Fulminant hepatic failure,;AST : ALT > 1 • AST value > 1000 = severe liver necrosis, AMI

17. TRANSAMINASES REMEMBER: Levels are often compared with results of other LFTs to help determine which form of liver d’s is present In most type of liver d’s ,ALT level > AST AST/ALT ratio is low AST : use for monitoring tx of potentially hepatotoxic drugs > 3x ULN  stop tx

18. Transaminases In Asymptomatic Patients Possible Causes of Chronic Elevation: 1. Alcohol or medication use 2. ChronicViral Hepatitis 3. Non-alcoholic fatty liver disease 4. Overweight (inc.ALT)

19. LIVER ENZYMES : LACTATE DEHYDROGENASE Cytoplasmic enzyme Non specific for liver LD4 Distribution of isoenzymes- LD1 LD2 LD4 LD5 LD5 LD1,LD2 Cardiac muscle, kidney,rbc LD1,LD2 LD TRANS Liver, skeletal muscle LD LD4,LD5 N value(TLD) =150 IU/l

20. LIVER ENZYMES : LD in Hepatitis Is slightly inc. but only transient ( low activity and short half life Large increment of total LD= 500 -1000 iu/l or+ elevated Alk.PO in the absence of other abn. Liver function tests (AST,ALT) TRANS LD CPK

21. LIVER ENZYMES : LD in Other Liver Diseases • Total LD + alkaline Phosphatase: = space occupying lesions (e.g.) • metastatic carcinoma • 1o hepatocellular carcinoma • Hemangioma (rarely) • Source of LD (LD5) : ? • hepatocytes • tumor • both

22. ALKALINE PHOSPHATASE • Distribution: • liver * • Bone * • kidney • intestine • placenta • Each of w/c • contain distinct isoenzymes Bulk * ALP ALP ALP ALP ALP

23. ALKALINE PHOSPHATASE Canalicular membrane Func.: facilitate transfer of metabolites across cell membranes ;lipid transport, & calcification process in bone synthesis Liver: exists predominantly in biliary tract a marker for biliary dysfunction R.V.=20-105 U/L (adults)

24. ALKALINE PHOSPHATASE Clinical Application • Obstruction of BT from: • Stones in duct • Infections • SOL • ALP (> 10 x ULN) • Reason for Increase: • Synthesis + excretion of ALP

25. ALKALINE PHOSPHATASE • hepatocellular disease (due to inflam/necrosis of the ductular lining cells) • Obst.Cholestasis (2x ULN,paralleling the rise of bili. ) • Partial obst. Inc. ALP & normal bili (dissociated jaundice) • CPC,liver-mod.elevated • SOL of liver Clinical application

26. Conditions in Which the Serum ALP is

27.  GLUTAMYL TRANSFERASE (GGT) Tissue distribution: • Kidney • Pancreas • Liver • Prostrate Ref.values: 3-35 U/L GGT GGT • 3-30 U/L GGT GGT

28.  GLUTAMYL TRANSFERASE (GGT) > 10x ULN in chronic cholestasis due to primary biliary cirrhosis or sclerosing cholangitis. > Inc. in 60-70% ---alcohol abuse; > most sensitive enzyme to determine liver damage from alcohol abuse > inc. in obst. disorders, SOL in the liver than w/ liver inj. > obese ; > high conc.of therapeutic drugs (acetaminophen,carbamazepine, Dilantine) Regulates the transport of a.a. across cell membranes by catalyzing the transfer of a glutamyl gr.from glutathione

29.  GLUTAMYL TRANSFERASE (GGT) • Application: • Detecting Alcoholic Liver Ds • Liver metastasis in • anicteric patient • Chronic obstruction of bile duct Increased Activity:

30. PROTEINS IN LIVER FUNCTIONTotal serum protein • Composed of : • Albumin • Globulins (1,2, , immuno globulins) • A/G ratio is 2:1 ; a reversal ratio favors renal / liver prob & chronic infect. • Ref. Range: 6-7.8 g/dL (60% is albumin, 3.5-5 g/dL)

31. PROTEINS IN LIVER FUNCTIONALBUMIN Functions: • Major osmotically active component of vascular system • Transport protein( e.g. for bilirubin & thyroid hormone) Synthesized by liver at 120 mg/kg/day

32. Hepatitis : total protein and albumin are w/in their normal range Fulminant hep : abnormally Cirrhosis : low Albumin together with PT are better indices of severity and prognosis of liver disease

33. Other Causes of dec. TP and ALB. Renal disease Protein losing enteropathy Malnutrition Chronic inflammatory diseases Severe burn An inc. in protein –Dehydration

34. BILIRUBIN METABOLISM Senescent rbc’s RES Heme Globin Amino acid pool RES Protoporhyrin Iron + Heme oxygenase Albumin Biliverdin Recycled into new rbc’s Bilirubin reductase Liver Albumin Unconjugated bilirubin + 2%-5% renal excretion Bilirubin glucoronide Bilirubin uridine diphosphate Glucoronyl transferase Bile Small intestine Alkal;ine pH + β-glucoronidase Unconjugated bilirubin Intestinal bacteria 20% reabosrobed Urobilinogen Urobilin (fecal pigment)

35. DISORDERS OF BILE PIGMENT METABOLISM Reference values: T serum bilirubin (A): 0.1 - 1 mg/dL (1.7 to 17 umol/L) Congugated Bilirubin (Direct): 0.3 mg/dL(5 umol/L) Unconjugated Bilirubin (Indirect): T Bilirubin – Conjugated Bilirubin

36. BILIRUBIN Serum / plasma , fasting state;shld.be tested ASAP Interference factors: Hemolysis- false dec lipemic – false inc light – false dec.

37. DISORDERS OF BILE PIGMENT METABOLISM • JAUNDICE/ICTERUS • Bilirubin deposition in sclera • and in skin • > 2.5 mg/dL (43 umol/L)

38. Impaired Bili Conjugation Physiologic jaundice of NB Breast milk jaundice Genetic Def. Of bili UGT (Criggler-Najar) Gilbert syndrome Diffuse Hepatocelular Ds Unconjugated Excess Bilirubin Prodxn Hemolytic Anemia Resorption of blood from internal hge Ineffective erythropoiesis (e.g.pernicious An, thalassemia Hepatic uptake Drug interference Some cases of Gilbert syndrome DISORDERS OF BILE PIGMENT METAB(HYPERBILIRUBINEMIA)

39. DISORDERS OF BILE PIGMENT METAB(HYPERBILIRUBINEMIA) Conjugated Dec. hepatic excretion of Bili Glucuronides Deficiency in canalicular membrane transporters (Dubin-Johnson syndrome, Rotor syndrome) In extrahepatic obst.,total bili rarely exceeds 25 ug/dl

40. Ammonia Derived mainly from a.a. & nucleic acid metabolism Metabolized only in the liver Px preparation: fasting,plasma, arterial good venipuncture technique,no fist clenching R.V. 19- 16 ug/dl

41. Alpha-feto protein • An onco-fetal protein • Marker of differentiation • Synthesized by fetal yolk sac, hepatocytes • Detectable during 4th wks. of pregnancy • Increased in : HCC , benign liver ds ( cirrhosis ) Testicular Tumors (embryonal &yolk sac) • Maybe inc. in breast,bronchial and colorectal Ca • Ref.value : < 20ng/ml > 400 ng/dl =HCC • Inc. neural tube defect

42. 6 Fundamental Patterns of Liver Function Tests

43. The end Good clinical history Complete P.E.