janet lim-dy, m.d., f,p.s.p. d.t.m.h
DESCRIPTION
JANET LIM-DY, M.D., F,P.S.P. D.T.M.H. EVALUATION OF LIVER FUNCTION TESTS. 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. - PowerPoint PPT PresentationTRANSCRIPT
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JANET LIM-DY, M.D., F,P.S.P. D.T.M.H.
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EVALUATION OF EVALUATION OF LIVER FUNCTION LIVER FUNCTION
TESTSTESTS
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Overview Overview 3 Systems involved in understanding liver function tests:
Hepatocyte
Biliary Tract: bili metabolism
•Proteins synthesis•Coagulation factors synthesis
RES: Immune sys. , Heme & globin metabolites
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KREBS CYCLE
GLUCONEOGENESIS
GLYCOLYSIS
HMP-SHUNT
FA SYNTHESIS & BREAKDOWN
LIPOPROTEIN METABOLISM
AA & NUCLEIC ACID METABOLISM
2 GENERAL METABOLIC PATHWAYS:1. AA-CHO PATHWAY involves ALT & AST
2. UREA CYCLE NH4 ureaEnzyme OCT unique to
liver
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LIVER FUNCTION TESTS
hepatic structure, cell integrity, function
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Reasons for requesting LFT:1. For Diagnosis2. For Differentiation
Is Hepatic damage due to primary hepatocyte damage or biliary system obstruction?
3. Prognosis / Monitoring
LIVER FUNCTION TESTSLIVER FUNCTION TESTS
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Liver EnzymesAminotransferases (ALT and AST)Lactate Dehydrogenase (LDH)Alkaline Phosphatase (Alk Phos) Glutamyl transferase (GGT)
TESTS FOR DISCLOSING TESTS FOR DISCLOSING HEPATIC DYSFUNCTIONHEPATIC DYSFUNCTION
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TESTS FOR DISCLOSING TESTS FOR DISCLOSING HEPATIC DYSFUNCTIONHEPATIC DYSFUNCTION
Total Protein Albumin
Gamma GlobulinsAlpha Globulins
Clotting FactorsProthrombinTimeHEPATOBILIARY DYSFUNCTION Serum Bilirubin ( total & direct)
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PATIENT PREPARATION & SPECIMEN COLLECTION
No special preparation requiredSerum : Preferred SpecimenHeparinized Plasma : Acceptable
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2 major aminotransferasesAST(SGOT) – Aspartate transferaseALT(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.
Liver Enzymes: Liver Enzymes: TransaminasesTransaminases
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Reaction catalyzed by ALT COOH CH3 COOH COOH | + | B6 | |
CH2 H C- CH2 C=O
| | | |
CH2 + COOH CH2 + COOH
| | pyruvate
C=O C-
| | COOH COOH
-ketoglutarate L-alanine L-glutamate
Liver Enzymes: Liver Enzymes: TransaminasesTransaminases
NH3
NH3
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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 enzymeElevation of ALT activitypersist longer
TransaminasTransaminaseses
AST
AST
ALT
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Reference value
ALT :
Males 10-40 U/L
Females 7-35 U/L
AST :
Males 15-40 U/L
Females 13-35 U/L
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Transaminases In Transaminases In Hepatobiliary DiseasesHepatobiliary Diseases
Mild:
PM damaged
Mitochondrial AST released into serum:
Disproportionate elevation----
(De Ritis quotient)
Cytoplasmic AST & ALT released into serum
More severe:Mitochondrial membrane damaged
ASTALT
Hepatocellular injury
ALT
AST
AST
80%
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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 damageHow to calculate AST/ALT ratio?
ex. AST= 52, ALT =67 52/67 = .75
AST / ALT > 2 ( 3:1 to 4:1) = ALDAST/ALT <1,most likely assoc. with other cause eg. Viral hep
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acute hepatitis : ALT is more increased than AST (20 -100 x the upper limit)AST is 10x the upper limit5-10x the upper limit in liver Ca
Transaminases Transaminases
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 > 1AST value > 1000 = severe liver necrosis, AMI
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TRANSAMINASESREMEMBER: Levels are often compared with results of other LFTs to help determine which form of liver d’s is presentIn most type of liver d’s ,ALT level > ASTAST/ALT ratio is lowAST : use for monitoring tx of potentiallyhepatotoxic drugs> 3x ULN stop tx
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Possible Causes of Chronic Elevation:1. Alcohol or medication use2. ChronicViral Hepatitis3. Non-alcoholic fatty liver disease
4. Overweight (inc.ALT)
Transaminases In Transaminases In Asymptomatic Patients Asymptomatic Patients
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Distribution of isoenzymes-
LD1
LD2
LD4
LD5
LIVER ENZYMES : LACTATE DEHYDROGENASE
LD
LDTRANSCardiac muscle, kidney,rbcLiver, skeletal muscle
LD1,LD2
LD1,LD2
LD4,LD5
LD4LD5
Cytoplasmic enzymeNon specific for liver
N value(TLD) =150 IU/l
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LDTRANS
CPK
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)
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Total LD + alkaline Phosphatase: = space occupying lesions (e.g.) metastatic carcinoma1o hepatocellular carcinomaHemangioma (rarely)
Source of LD (LD5) : ?hepatocytestumorboth
LIVER ENZYMES : LD in Other Liver Diseases
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ALKALINE PHOSPHATASE
Distribution:
liver *
Bone *
kidney
intestine
placenta
Each of w/c
contain distinct isoenzymes
ALP
ALP
ALP
ALP
ALP
Bulk *
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Liver: exists predominantly in
biliary tract a marker for biliary
dysfunction
ALKALINE PHOSPHATASE
R.V.=20-105 U/L (adults)
Canalicular membrane Func.: facilitate transfer of metabolites across cell membranes ;lipid transport, & calcification process in bone synthesis
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ALKALINE PHOSPHATASE
Clinical Application
Obstruction of BT from:
Stones in duct
Infections
SOL
ALP (> 10 x ULN)
Reason for Increase:
Synthesis + excretion of ALP
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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
ALKALINE PHOSPHATASE
Clinical application
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Hepatobiliary Ds
Bone Ds Other Conditions
Obstructive jaundice
Osteitis deformans
Healing fractures
Biliary cirhosis
Rickets Normal growth
Intrahep cholestasis
Osteomalacia Pregnancy
SOL(granuloma,abscess,metastatic ca)
Hyperthyroidism
Note: dec. ALP is seen in malnutrition
Viral hepatitis Metastatic bone ds
hypophosphotasia
Cirrhosis Osteogenic Sa
Conditions in Which the Serum ALP Conditions in Which the Serum ALP is is
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Tissue distribution:
KidneyPancreasLiverProstrate
Ref.values: 3-35 U/L
GLUTAMYL TRANSFERASE (GGT)
GGT
GGTGGT
GGT3-30 U/L
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> 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
GLUTAMYL TRANSFERASE (GGT)
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GLUTAMYL TRANSFERASE (GGT)
Increased Activity:Application:
Detecting Alcoholic Liver Ds
Liver metastasis in anicteric patient
Chronic obstruction of bile duct
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Composed of :AlbuminGlobulins (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)
PROTEINS IN LIVER FUNCTION
Total serum protein
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Functions:Major osmotically active component of vascular systemTransport protein( e.g. for bilirubin & thyroid hormone)
Synthesized by liver at 120 mg/kg/day
PROTEINS IN LIVER FUNCTIONALBUMIN
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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
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Other Causes of dec. TP and ALB. Renal disease Protein losing enteropathy Malnutrition Chronic inflammatory diseases Severe burn
An inc. in protein –Dehydration
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Heme Globin
Iron Protoporhyrin
Biliverdin
Liver
Recycled into new rbc’s
Unconjugatedbilirubin
Albumin
RESSenescent
rbc’s Amino acid pool
RES
+Heme oxygenase
Bilirubin reductase
+
Albumin
2%-5% renal excretion
Bilirubin glucoronide
Urobilinogen
Unconjugated bilirubin
Urobilin (fecal pigment)
Small intestine
20% reabosrobedIntestinal bacteria
Alkal;ine pH + β-glucoronidase
BileBilirubin uridine diphosphate
Glucoronyl transferase
BILIRUBIN METABOLISM
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DISORDERS OF BILE PIGMENT METABOLISMReference 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
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BILIRUBIN
Serum / plasma , fasting state;shld.be tested ASAP
Interference factors: Hemolysis- false dec lipemic – false inc light – false dec.
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JAUNDICE/ICTERUS
Bilirubin deposition in sclera and in skin
> 2.5 mg/dL (43 umol/L)
DISORDERS OF BILE PIGMENT METABOLISM
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Impaired Bili Conjugation Physiologic jaundice of
NB Breast milk jaundice Genetic Def. Of bili UGT
(Criggler-Najar) Gilbert syndrome Diffuse Hepatocelular
Ds
UnconjugatedExcess Bilirubin Prodxn
Hemolytic AnemiaResorption of blood from internal hgeIneffective erythropoiesis(e.g.pernicious An,
thalassemia
Hepatic uptake Drug interference Some cases of Gilbert
syndrome
DISORDERS OF BILE PIGMENT DISORDERS OF BILE PIGMENT METABMETAB
(HYPERBILIRUBINEMIA)(HYPERBILIRUBINEMIA)
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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
DISORDERS OF BILE PIGMENT DISORDERS OF BILE PIGMENT METABMETAB
(HYPERBILIRUBINEMIA)(HYPERBILIRUBINEMIA)
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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
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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
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CONDITION AST ALT
LD ALP TP
ALB BIL NH4
1 H H H H N N H N 2 N N N N-
slH
L L H H
3 N N N H N N N-H
N
4 N or
HN or H
H H N N N-H
N
5 sl H sl H
sl H
N-sl H
N N N-SlH
N
6 Very
HH H H L L H H
6 Fundamental Patterns of Liver Function 6 Fundamental Patterns of Liver Function TestsTests
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The end
Good clinical history Complete P.E.