Transcript Functions of the liver • Carbohydrate metabolism • Gluconeogenesis • Glycogen synthesis and breakdown • Fat metabolism • Fatty acid synthesis • Cholesterol synthesis and excretion • lipoprotein synthesis •

Functions of the liver
• Carbohydrate metabolism
• Gluconeogenesis
• Glycogen synthesis and
breakdown
• Fat metabolism
• Fatty acid synthesis
• Cholesterol synthesis and
excretion
• lipoprotein synthesis
• Ketogensis
• bile acid synthesis
• 25-hydroxylation of vitamin D
• Protein metabolism
• synthesis of plasma proteins
• Some coagulation factor
• Urea synthesis
• Hormonal metabolism
• Meabolism and excretion of
steroid hormones
• metabolism of polypeptide
hormones
• Drugs and foreign compounds
• metabolism and excretion
• Storage
• Glycogen, Vitamin A , B12 , iron
• Metabolism and excretion of
bilirubin
Dr/ Ragaa Salama
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Functions of the Liver & Liver Function Tests
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Classified into :
1-Metabolic
2-hematological function
3-Excretory function measure bilirubin
4-storage
5-serum enzymes derived from liver AST, ALT, ALP.
GGT, 5’ nucleotidase.
• 6- Synthetic function Serum protein , albumen,
prothrombin time
• 7-detoxification and phagocytosis.
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Liver Function Tests
•biochemical investigation to detect the abnormalities and the
extent of liver damage
•Alanine aminotransferase(ALT) or SGPT
•Aspatate aminotransferase (AST) or SGOT
•Total protein
• albumin / globulin ratio ( A / G ratio)
•Alkaline phosphatase
•Bilirubin
•5'Nuclotidase
•Gamma Glutamyl transferase ( GGT).
•Alpha fetoprotein (AFP).
•Lactate dehdrogenase (LDH).
•Ammonia
•Prothormbin time
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Liver Function Tests
Liver chemistry test
Clinical implication of abnormality
ALT
Hepatocellular damage
AST
Hepatocellular damage
Bilirubin
Cholestasis, impair conjugation, or biliary obstruction
ALP
Cholestasis, infiltrative disease, or biliary obstruction
PT
Synthetic function
Albumin
Synthetic function
GGT
Cholestasis or biliary obstruction
Bile acids
Cholestasis or biliary obstruction
5`-nucleotidase
Cholestasis or biliary obstruction
LDH
Hepatocellular damage, not specific
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Principle: transamination reaction
C O OH
HC
C O OH
C O OH
NH 2
+
C
G PT, ALT
O
CH3
CH2
A la n ine
CH2
PLP
C
O
C O OH
HC
+
CH3
CH2
P y ru v ate
CH2
C O OH
C O OH
G lu ta m a te
 -K eto g lu tara te
C O OH
HC
NH
C O OH
C O OH
2
+
C
O
CH2
CH2
C O OH
CH2
A sp a rta te
NH 2
G O T, A S T
PLP
C
O
C O OH
+
NH
CH2
CH2
C O OH
CH2
O x a lo ac eta te
C O OH
HC
2
C O OH
G lu ta m a te
 - K eto g lu tara te
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Alanine aminotransferase(ALT )
Aspatate aminotransferase (AST)
• Enzymes reflect hepatocellular damage.
• Transfer of amino groups from aspartate or alanine to αKetoglutarate leading to formation of oxaloacetate and
pyruvate.
• ALT is found mainly in liver cells, more specific to liver
• It is sensitive index of acute hepatocellular injury
• Causes of increased level:
• 1- hepatitis
2- cirrhosis
3-obstructive jaundice
• AST is found mainly in cardiac, hepatic, muscle and kidney.
• AST  following myocardial infarction ,a peak 48-60 h after
infarction
Dr/ Ragaa Salama
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Estimation of Alanine aminotransferase (ALT ) (SGPT)
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Principle: the rate of decrease in the absorbance is proportional to ALT activity
ALT
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α- Ketoglutarate + alanine
glutamate + pyurvate
LDH
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Pyurvate +
Procedure:
NADH+H
lactate + NAD+ + H2o
Test
Reconstituted reagent
3ml
Pre-warmed at 37 ºC then added :
Sample
0.2 ml (200 µl)
Mix and incubate at 37ºC for 1 min. Read the absorbance A1 at
340nm against d H2O . Re-incubate at 37ºC and after exactly 3
min read the absorbance (A2 ) .
Calculation:
( A1
A2 ) x 857 U/L
Normal value of ALT = 5-40 U/L
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Dr/ Ragaa Salama
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Estimation of Aspartate aminotransferase (AST ) (SOPT)
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Principle: the rate of decrease in the absorbance is proportional to AST activity
AST
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α- Ketoglutarate + aspartate
glutamate + oxaloacetate
MDH
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oxaloacetate +
Procedure:
NADH.H+
L-Malate + NAD+ + H2o
Test
Reconstituted reagent
3ml
Pre-warmed at 37 ºC then added :
Sample
0.2 ml (200 µl)
Mix and incubate at 37ºC for 1 min. Read the absorbance A1 at
340nm against d H2O . Re-incubate at 37ºC and after exactly 5
min read the absorbance (A2 ) .
Calculation:
( A1
A2 ) x 514 U/L
Normal value of AST = 5-40 IU/L
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Bilirubin
Produced by catabolism of old RBCs and other hemoproteins (
cytochrom oxidase, P-450).
Normal level ( total) is ≤ 1 mg/dl (17.1 µmol /L)
direct ≤ 0.2 mg/dl
Hyperbilirubinemia :bilirubin in the blood 1.0 mg/dL.
Genral Causes of Hyperbilirubinemia :
1-    production of bilirubin more than liver capacity,
2-liver cell damage 3-failure of liver to excrete it in bile
4- obstruction of bile pathways.
At bilirubin blood level of 2 - 2.5 mg/dL, bilirubin diffuses to
tissues (e.g., skin, mucous membranes and sclera of the eyes)
and stains them yellow, a condition called jaundice or icterus.
Kernicterus: high level of unconjugated bilirubin can pass
immature blood brain barrier causing a necrotic syndrome
that occurs from bilirubin neurotoxicity usually in low birth
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weight infant.
Bilirubin Metabolism
stercobilnogen
in stool
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• Van den Bergh reaction
• This is specific reaction to identify the increase in serum
bilirubin level .
• Normal serum gives a negative Van den Bergh reaction .
• Principle
• Van den Bergh reaction is a mixture of sulfanilic acid and
sodium nitrate
• sulfanilic acid + sodium nitrate → Diazotized
sulfanilic acid
• Diazotized sulfanilic acid + bilirubin → Azobilirubin (
purple color).
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Procedure : pipette in a clean dry test tubes:
Blank
Test
sulfanilic acid
3ml
3ml
sodium nitrate
-
0.05 ml
d H 2O
0.05 ml
-
0.2ml (200 µl)
0.2ml (200 µl)
Mix and wait for 1min
Serum sample
After 1 min read the absorbance of test and blank at 540nm against d H2O
( direct biliurbin) then add
Methanol
3ml
3ml
Mix by inversion and wait for 5 min read the absorbance of test and blank at
540nm against d H2O ( total biliurbin)
Standard: Pour Bilirubin Equivalent Standard (2.5 mg/dl then 5 mg/dl )into a
clean vial, read and record its absorbance against d H2O at 450 nm
Calculation:
direct biliurbin= A (test)- A(blank) x 2.5 mg/dl
A (standard)
Total bilirubin= A (test)- A(blank)Dr/
x 5Ragaa
mg/dl
Indirect bilirubin=total - direct
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A (standard)
Comparison between 3 types of jaundice
Hemolytic
J aundice
Bilirubin
Obstructive
J aundice
Unconjugated  Conjugated 
Hepatic
J aundice
Both 
VonDenBerg Indirect +
Direct +
Biphasic
Serum
enzymes
ALT,AST,ALP
normal
ALP  
ALT,AST 
ALT,AST  
ALP 
Bilirubin
In urine
Not excreted
excreted
excreted
urobilinogen
Excreted 
Normal or ↓
Normal or ↓
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Types of Hyperbilirubinemias (Jaundice)
I- Uncojugated hyperbilirubinemia: causes:
Hemolytic diseases: Hemolytic anemia , Rh incompatability, G6PD.
the unconjugated hyperbilirubinemia is mild because of the ability of adult
liver to get rid of bilirubin.
Neonatal (Physiological) jaundice: ↑hemolysis due to immature hepatic
system.
Treated by phenobarbital and blue light phototherapy → bilirubin excretede in
bile without conjugation.
Crigler-Najjar syndrome type I and II: It is an autosomal recessive absence
or deficiency of UDP-glucuronyltransferase in the liver. Treated by
phenobarbital and
blue light phototherapy may be fatal by age 15 months.
Gilbert syndrome: harmless mild hyperbilirubinemia due ↓ UDPglucuronyltransferase.
Toxic hyperbilirubinemia: liver cell damage by CCl4, cirrhosis, viral hepatitis
and chloroform.
Brest feed hyperbilirubinemia: β –glucurnidase in breast milk which
deconjugate bilirubin
Lucy-drescall syndrom: familial ,mild,last 2-3 weeks due to inhibitor of
congjugation
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II - Conjugated hyperbilirubinemia: causes :
Obstructive (cholestatic) jaundice:
It is due to the obstruction of hepatic or common bile ducts that regurgitate
conjugated bilirubin into the blood with choluria.
Chronic idiopathic jaundice (Dubin-Johnson and Rotor
syndromes):
They are benign inherited defect in transport system of conjugated bilirubin.
Alkaline phosphatase
• ALP is present at or in cell membrane .
• The response of the liver to any form of biliary tree obstruction is to induce
the synthesis of ALP.
• The main site of new enzyme synthesis is the hepatocytes adjacent to the
biliary canaliculi.
• Some of the newly formed enzyme enters the circulation to raise the enzme
level in serum
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Alkaline phosphatase
principle
Hydrolysis of p-nitrophenyl phosphate → alkaline pH→ yellow p-nitrophenoxide
ions.
test
Working reagent
1 volume of ALP substrate + 9 vol of ALP buffer →1ml
Pre-worm at 37ºC
add
sample
20 µl serum
Mix and incubate at 37ºC for 1 min.
Read the absorbance A1 at 405 nm against d H2O .
Re-incubate at 37ºC and after exactly 3min read the
absorbance (A2 ) →
calculation
∆A
∆ A/min = A2 -― A1 / 2 , ∆ A/min X 2720 =
Dr/ Ragaa Salama
U/L
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Alkaline phosphatase
• ALP is present at or in cell membrane, Its function by 3 ways
• 1- Hydrolysis
2-Phosphotrnsferase
3- pyrophosphtase
• Sources : Liver , bone ( osteoblast), intestinal epithelial cells
proximal convoluted tubules of the Kidney and placenta .
• Clinical significance:
• Physiological causes: growing children , healing of bone
fracture, 3rd trimester of pregnancy from placenta, lactation.
• Pathological causes :
• 1- hepatobiliary dis ( extrahepatic ,intra hepatic obstruction),
Infectious hepatitis
• 2- bone dis. associated with increase osteoblastic activity like
Paget’s disease (10-25 fold) as osteoblast rebuild bone that
resorbed by uncontrolled activity of osteoclast, osteogenic bone
cancer
• Moderate rise in osteomalacia but normal in osteoprosis,
• rickets (2-4 fold),Fanconi Dr/
Syndrom,1ry&2ry
hyperparathyrodism
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Albumin
Synthesized mainly by the liver
Osmotic effect
Transport substances
Half life is 3 weeks
It decreased in liver diseases
Non-hepatic causes of hypoalbuminemia(
Differential diagnosis) :
Decreased synthesis : malnutrition, malabsorbtion,
malignant diseases.
Increased catabolism : injury, postoperative
Acute inflammation
Chronic inflammation
Increased loss ( nephrotic syndrome, protein –losing
enteropathy, burns, exudative skin disease
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• Liver is the primary site for synthesis of plasma
proteins
• In acute hepatic dysfunction , little changes
• In chronic, ↓ albumen, globulin, A/G ratio is
inverted in chirrosis.
• ↓ albumen, in sever liver disease, in active hepatitis
suggests a poor prognosis.
• In portal hypertension, albumen leaks of liver
surface→ peritoneal cavity → osmotic pressure of
peritoneal cavity → ascities.
•  α 1 globulin, α 1 antitrypsin, α 2 & β globulin in
cirrhosis, chronic cholestasis due to  production
and ↓ clearance.
• IgG  autoimmune Dr/hepatitis&
cirrhosis.
Ragaa Salama
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Estimation of serum albumin
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Principle
Albumin+ Bromocresol green
Albumen color
reagent
Albumin bromocresol green complex
Blank
Standard
test
2.5 ml
2.5 ml
2.5 ml
Standard
-
sample
-
0.2ml (200 µl)
-
-
0.2ml (200 µl)
Mix and allow to stand at room temp. For 5 min
Set wavelength at 54 0 nm and zero instrument with the blank .
Read absorbance of all tubes within min.
Calculation:
A (test)
x 5 g/dl ( concentration of standard)
A (standard)
Dr/ Ragaa Salama
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Estimation of serum total protein
• Principle
• Protein + Biurt reagent( Cu+2)
Blank
Alkaline pH
Cu+2-protein complex
( blue color).
standard
test
Biuret reagent
1 ml
1 ml
1 ml
standard
-
(20µl )
-
sample
-
-
0.02 ml (20µl)
Mix and let stand at room temp. for 10min.
Read the absorbance of standard and test at 540 nm against blank
Calculation:
A (test)
x 5 g/dl ( concentration of standard)
A (standard)
Dr/ Ragaa Salama
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5'Nuclotidase
• Indication: Isolated increase in alkaline
phosphatase.
• Alkaline phosphatase and 5'Nuclotidase
usually increase and decrease in parallel in
hepatobiliary disease.
• Alkaline phosphatase and 5’ nuleotidase: found
near the bile canalicular membrane of
hepatocytes REFLECT CHOLESTASIS
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• Gamma Glutamyl transferase ( GGT).
•  in all types of liver diseases
α- fetoprotein
 hepatocelular carcinoma ,
 Acute & chronic hepatitis.
 It is present in early fetal life and reappear
in malignant liver, used as tumor marker
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Coagulation factors:
With the exception of Factor VIII, the blood
clotting factors are made exclusively in
hepatocytes.
Because of their rapid turnover, measurement of
the clotting factors is the single best acute
measure of hepatic synthetic function and
helpful in both the diagnosis and assessing the
prognosis of acute parenchymal liver disease
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• Serum prothrombin time: collectively measures
factors II, V, VII, and X
Marked prolongation of prothrombin time, > 5s
above control is a poor prognostic sign in acute
viral hepatitis and other acute and chronic liver
diseases.
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