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Liver Function Tests
1. Liver Function Tests
DR. FARHANA ATIA
ASSOCIATE PROFESSOR
DEPARTMENT OF BIOCHEMISTRY
NILPHAMARI MEDICAL COLLEGE, NILPHAMARI
2. Liver Function Tests
LFT or liver panel are a
group of tests that help in
Diagnosis of liver disease,
monitor therapy &
assess prognosis of liver
disease
4. Liver Function Tests
Test Function assessed Utility
1. Serum bilirubin
(total &
conjugated)
Conjugation &
excretory function
D/D of jaundice
2. Total serum
protein & albumin
Biosynthetic function Indicator of severity of
chronic liver disease
3. Prothrombin
time
Biosynthetic function Indicator of severity of
acute liver disease
5. Liver Function Tests
Test Function assessed Utility
4. Serum
enzymes
AST, ALT
ALP, GGT
Hepatocellular
integrity
Biliary obstruction
• Early indicator of
damage
• Cholestasis
5. Blood
ammonia
Detoxification • ↑ in cirrhosis of liver
with portal
hypertension
• Disorder in urea cycle
6. Test for Synthetic Function
Total Plasma Protein- 6.0-8.3 g/dl 60-83 g/L
Serum albumin- 3.4-5.4 g/dl
Albumin is solely synthesized by liver
Half life is 3wks (20-25 days)
Low level indicates chronic liver disease, malnutrition
Immunoglobulin is not synthesized in liver. So A/G
ratio is altered in liver disease
7. Test for Synthetic Function
Half life of Prothrombin is 5-72 hours
In liver disease there are decreased of plasma clotting
factors
Assessed by lab by PT
PT is prolonged in liver damage (Acute LD, also in
chronic disease
Vitamin K (required for factor II, VII, IX, X) deficiency
should be ruled out by measuring prothrombin time
before & after vitamin K administration
8. Bilirubin Metabolism
After ≈120 days in the circulation,
RBC are taken up and degraded by the
mononuclear phagocyte system (MPS), particularly in
the liver & spleen
Breakdown of heme to bilirubin in macrophages
Unconjugated bilirubin (complexed to albumin) is
transported through the blood to the liver
9. Bilirubin Metabolism
Bilirubin is taken up
via facilitated diffusion
by the hepatocyte &
conjugated with
glucuronic acid to form
bilirubin diglucuronide
10. Bilirubin Metabolism
Conjugated bilirubin is
actively secreted into bile
and then the intestine
In the intestine,
glucuronic acid is removed
by bacteria. The resulting
bilirubin is converted to
urobilinogen
11. Bilirubin Metabolism
Some of urobilinogen is reabsorbed
from the gut & enters the portal blood
A portion of urobilinogen participates
in the enterohepatic urobilinogen cycle
The reminder is transported by the
blood to the kidney, where it is
converted to yellow urobilin & excreted,
giving the urine its characteristic color
Urobilinogen
14. Terminology
Jaundice: Refers to the yellowish discoloration of sclera, conjunctiva,
skin & mucous membrane due to deposition of bilirubin secondary to
hyperbilirubinemia
Icterus: Greek term for jaundice
Kernicterus: Bilirubin encephalopathy. It is a neurological syndrome
resulting from destruction of basal ganglia by deposition of bile pigment
in severe hemolytic anemia specially in premature infant whose BBB is
underdeveloped
15. Classification of Jaundice
Hemolytic
(prehepatic)
• Hemolysis/ abnormal
RBC
• Antibodies
• Drugs & toxins
• Thalassemia
• Hemoglobinopathies
Hepatocellular
(hepatic)
• Viral hepatitis
• Toxic hepatitis
• Intrahepatic
cholestasis
• Gilbert's syndrome
• Criglar-Najjar
syndrome
Obstructive
(posthepatic)
• Extrahepatic
cholestasis
• Gall stone
• Tumors of bile duct
• Carcinoma head of
the pancreas
• Carcinoma ampulla
of Vater