The document outlines liver function tests (LFTs) and their significance in evaluating liver health, covering its metabolic, excretory, synthetic, storage, and protective functions. It describes various laboratory tests for diagnosing hepatobiliary diseases, including serum bilirubin levels and liver enzymes, while highlighting conditions leading to liver dysfunction. Additionally, it addresses congenital bilirubin disorders and the importance of interpreting specific biochemical tests in assessing liver damage and function.

1. LIVER FUNCTIONTESTS

2. Liver Functions
• Metabolism
 CHO, Protein & amino acids, Fat Metabolism
• Excretion & Detoxification
 Bile pigments, bile salts and cholesterol (Excreted in bile into
intestine);Ammonia(detoxification)
• Synthetic Function
 Plasma proteins/Clotting Factors
• Storage Function
 Glycogen, vitamins A, D and B12,and trace element iron
• Protective functions and detoxification
Kupffer cells perform phagocytosis

3. Classification Of LFTs
• No single biochemical test can detect the global
functions of liver
• ? Based on individual Liver Functions
• ‘True’ tests of liver function
• Tests indicative of liver injury or biliary tract disease.
• Many of the tests reflecting the health of the liver are
not direct measures of its function.

4. Lab Evaluation of hepato-biliary disease
•Routine Tests
• Serum bilirubin
• Transaminases (ALT ,AST)
• Alkaline phosphatase
• Albumin
• Gamma gltamyltransferase
• Total protein
• Urinary bilirubin
• Urobilinogen
• Coagulation factors

5. Lab Evaluation of hepato-biliary disease
• Specific Tests
• Serum alpha 1-antitrypsin
• Alpha fetoprotein
• Hepatitis serological markers
• Specific auto-antibodies
• Immunoglobulins
• Ceruloplasmin
• Pro-collagen III peptide
• Copper
• Serum iron studies

6. via bile duct to intestines
Stercobilin
excreted in feces
Urobilinogen
formed by bacteria KIDNEY
Urobilin
excreted in urine
BLOOD
CELLS
CO
Biliverdin IX
Heme oxygenase
O2
Bilirubin
(water-insoluble)
NADP+
NADPH
Biliverdin
reductase
Heme
Globin
Hemoglobin
reabsorbed
into blood
LIVER
Bilirubin diglucuronide
(water-soluble)
2 UDP-glucuronic acid
Bilirubin
(water-insoluble)
via blood
to the liver
INTESTINE

7. Serum Bilirubin
• Normally, a small amount of bilirubin circulates in the
blood. Serum bilirubin is considered a true test of
liver function, as it reflects the liver's ability to take up,
process, and secrete bilirubin into the bile.
• Total Bilirubin
• Direct Bilirubin
• Indirect Bilirubin

8. HPLC Based Fractions of Bilirubin
• Alpha ( -bilirubin)
α
• Beta bilirubin ( -bilirubin)
β
• Gamma ( -bilirubin)
ϒ
• (delta) -bilirubin
δ

9. Classification of Bilirubin based on
Diazo Reaction
• Direct Bilirubin:
Beta (monocojugated)
Gamma (diconjugated)
Delta bilirubin
• Indirect Bilirubin
Alpha (unconjugated) bilirubin

10. Disorders of The Liver
• Congenital
 Gilbert’s Disease
 Crigglar-Najjar
 Dubin-Johnson syndrome
 Rotor’s syndrome
• Hepatitis
 Acute
 Chronic
• Cholestasis
 Extrahepatic
 Intrahepatic
• Cirrhosis
• Anoxia
• Infiltrations
• Drug Toxicity

11. Congenital Causes of Hyperbilirubinaemia
Unconjugated Bilirubinaemia
Gilbert syndrome:
Crigler-Najjar
Conjugated Bilirubinaemia
Dubin-johnson syndrome:
Rotar Syndrome

12. Gilbert's Syndrome
• The most common inherited disorder of bilirubin
glucuronidation (9-10% of the adult population)
• Also called "constitutional hepatic dysfunction" and
"familial non-hemolytic jaundice"
• Enzyme Defect: Uridinediphosphoglucuronate
glucuronosyltransferases (UGTs) which is a family of
enzymes that mediate glucuronidation of various
endogenous and exogenous compounds
• Genetic Defect: The mutation is in the promoter
region, upstream to exon 1 of the gene encoding bilirubin-
UGT

13. Haemolytic Disease of the Newborn (HDN)
• RBCs of the fetus or newborn are destroyed
by maternally-derived alloantibodies.
• These antibodies arise in the mother as the
direct result of a blood group incompatibility
between the mother and fetus (Mother Rh-D
negative , Fetus Rh-D Positive )
• In developed world very high incidence has
been reduced due to immunization of Anti D.

14. Neonatal (Physiological) Jaundice
• FullTerm infants Jaundice lasts for about 10 days
with a rapid rise of serum bilirubin up to 204
µmol/L (12 mg/dL).
• Preterm infants Jaundice lasts for about two weeks,
with a rapid rise of serum bilirubin up to 255
µmol/L (15 mg/dL).

15. Pathological Neonatal Jaundice
• Any of the following features
characterizes pathological jaundice:
• Clinical jaundice appearing in the first 24 hours
• Jaundice lasting more than 14 days of life.
• Increases in the level of total bilirubin by more than
8.5 µmol/L (0.5 mg/dL) per hour or (85 µmol/L)
5 mg/dL per 24 hours.
• Total bilirubin more than 331 µmol/L (19.5 mg/dL)
• Direct bilirubin more than 34 µmol/L (2.0 mg/dL).

16. Urine Bilirubin
• The presence of urine bilirubin indicates hepatobiliary
disease.
• Conjugated bilirubin may be found in urine when the
serum bilirubin levels are normal (Early AVH)
• Tests strips impregnated with diazo reagent are used to
detect bilirubin in urine

17. Hepatic Transaminases
• ALT is mainly a cytoplasmic enzyme
• AST has two fractions :
• Cytoplasmic AST
• Organellar AST
• In Acute Hepatitis, only cell membrane is damaged
while organelles remain intact
• So in Acute Hepatitis ALT is markedly increased as
compared to AST

18. HepaticTransaminases (Cont)
• ALT may be the first or only liver marker to rise
• In Chronic Hepatitis AST is a better marker
• AST lacks specificity
• So for diagnosis and monitoring of Chronic Hepatitis
(Hep B and C),ALT can be used.

19. AlanineAminotransferse
• Also known as Alanine transaminase,L-alanine:2-
oxoglutarate aminotransferase
• Formerly glutamic pyruvic transaminase (GPT)
• Groups of ezyme catalyze the interconversion of
amino acids to 2-oxo-acids
• Tissue sources of enzyme are liver,
kidney,heart,skeletal muscles,spleen and lungs.

20. Clinical Significance
• Liver disease is the most important cause of increased
ALT activity.
• In viral hepatitis , serum ALT levels are elevated even
before jaundice is detected clinically
• Values may reach as high as 100 X URL
• Peak enzyme values occur between 7 and 12 days
• Activity gradually decreases reaching normal levels by
third to fifth week
• ALT/AST(De Ritis)ratio >1 in infectious hepatitis and
other inflammatory conditions
• Cell necrosis alters ALT/AST ratio

21. Conditions causing raisedALT
Alcoholic liver disease
Cancer of the liver
Cholestasis or congestion of the bile ducts
Cirrhosis or scarring of the liver with loss of function
Hepatitis or inflammation of the liver
Noncancerous tumor of the liver
Use of medicines or drugs toxic to the liver

22. Membrane Bound Hepatic Enzymes
• Membrane bound hepatic enzymes are:
• Alkaline Phosphatase (ALP)
• Gamma GlutamylTransferase (Gamma GT)
• 5-prime Nucleotidase
• Increased in Cholestasis
• Bound with cell membranes of endothelial cells of bile
canaliculli
• Obstruction and stasis cause digestion of fat content
of cell membranes.

23. ALP-Considerations in interpretation
• Serum ALP measurements are of particular interest in
the investigation of two groups of conditions:
hepatobiliary disease and bone disease associated with
increased osteoblastic activity.
• Recognition of low ALP activity is equally important and
establishing and advising of appropriate reference
intervals is therefore recommended

24. Considerations in interpretation(Contd)
• The form present in the sera of normal adults probably
originates mainly in the liver, with up to half the total
activity coming from the skeleton.
• Normal ALP levels are age-dependent and levels are
elevated during periods of active bone growth.
• In humans, alkaline phosphatase is particularly
concentrated in liver, bile duct, kidney, bone, intestinal
epithelium and the placenta.

25. Considerations in Interpretation(Contd)
• Levels are significantly higher in children and pregnant
women.
• ALP levels are affected by many drugs, physical
conditions, herbal medicines, food intake, smoking,
alcohol intake, and pregnancy

26. Gamma GlutamylTransferase
• Found in hepatocytes and biliary epithelial cells
• Levels rise in hepatobilirary disease
• Lacks specificity
• Other causes for : Pancreatic disease, myocardial
infarction, renal failure, chronic obstructive pulmonary
disease, diabetes, and alcoholism
• Identification of patients with occult alcohol use
• Used in evaluation of liver origin of other raised
enzymes like AP

28. Albumin
• Major protein of human plasma(35-50g/l)
• Approx 60% of the total plasma protein
• t1/2 is approx 19 days
• Migrates fastest in the electrophoresis at
alkaline pH
• Synthesized in liver, and synthesis reduced
in acute phase
• Distributed mainly in ECF , with abt 40%
located intracellular compartment

29. Albumin
• Albumin level is not a reliable indicator of hepatic
protein synthesis in acute liver disease.
• Decreased levels in CLD and cirrhosis
• Hypoalbuminemia: not specific for liver (protein
malnutrition, nephrotic syndrome and chronic protein
losing enteropathies.)

30. ProthrombinTime
• Prothrombin is formed in the liver from inactive
“preprothrombin” in presence of vitamin K.
• PT is used to assess the activity of extrinsic blood clotting
pathway .
• A useful test of liver function as well.
• Elevated PT indicates either vitamin K deficiency due to
prolonged jaundice and malabsorption of vitamin K or
significant hepatocellular dysfunction.
• Failure of PT to correct with parenteral administration of
vitamin K indicates severe hepatocellular injury.