This document provides information on liver function tests. It discusses the three main systems that make up the liver and its key functions including metabolism, excretion, protection and detoxification, and synthesis. It then describes various laboratory tests used to evaluate liver disease and dysfunction, including tests of excretory function (bilirubin, bile salts), enzymes (ALT, AST, ALP), synthetic function (albumin, PT), and specialized tests. Causes of liver dysfunction like hepatitis, cirrhosis, and tumors are also mentioned.

1. Liver function Test
Binaya Tamang
Lecturer
UCMS -TH

2. Introduction
• Liver is mainly composed of 3 system
1)hepatocytes: metabolic reaction and macromolecules,
esp protein synthesis and degradation
2)biliary system: metabolism of bilirubin and bile salts
3)reticuloendothelial system: immune system and
production of heme and globin metabolites.

3. Function
Liver performs several diversified functions. lt is the central
organ of body's metabolism.
Metabolic functions: carbohydrate, lipid, protein, mineral
and vitamin metabolisms.
Excretory functions : Bile pigments, bile salts and cholesterol
Protective functions and detoxification : Kupffer cells
perform phagocytosis to eliminate foreign compounds.
• Ammonia is detoxified to urea.
• for the metabolism of xenobiotic (detoxification).

4. Contd…
Synthetic function:
• formation of blood (particularly in the embryo),
• Albumin is solely synthesized in liver.
• synthesis of almost all the plasma proteins except
immunoglobulin's (including blood clotting factors) .
Storage functions :
• Glycogen, vitamins A, D and B12 and trace element iron are
stored in liver

5. Liver Dysfunction
• Hepatitis: damage to the liver cells ( viral , toxic ,alcoholic)
• Cirrhosis: fibrous tissue formation leads to the shrinkage of
liver, decreased hepatocellular function and obstruction of bile
flow.
• Tumors, most frequently secondary; for instance metastases
cancer of large bowel, lungs , stomach and breast cancer
• Alcoholic liver disease
• Jaundice: types
• Coagulation disorders

6. Liver functions test
• Numerous laboratory investigations have been proposed in the
assessment of liver diseases
• Detecting
• Diagnosing
• Evaluating severity
• Monitoring therapy
• Assessing the prognosis of liver disease and dysfunction.

7. Standard liver function test
• Total protein
• Serum albumin and A/G ration
• Total and conjugated bilirubin
• Liver enzymes:
a) amino transferases ( ALT, AST)
b) Alkaline phosphatase
c) gamma glutamyl transferase
d) 5’ nucleotidase
e) LDH
• Protrombine time / INR

8. Other special tests
• Alfa 1 antitrypsin
• Ceruloplasmin
• Transferrin
• Ferritin
• Alfa fetoprotein
• Blood ammonia
• Bile salts and urobilinogen
• Antibodies detection
• Galactose tolerance Test-
metabolic
• Bromosulphathelein Test-
excretory
• Hippuric acid synthesis Test-
detoxification

9. Classification of LFT
1. excretory function- Measurement of bile pigments, bile salts,
bromosulphthalein.
2. serum enzymes derived from liver-Determination of
transaminases, alkaline phosphatase, 5'-nucleotidase,gamma
glutamyltransferase.
3. metabolic capacity- Galactose tolerance, anti pyrine
clearance.
4. synthetic functions-Prothrombin time, serum albumin
5. detoxification-Hippuric acid synthesis

10. Tests of hepatic excretory
function
i. Serum – Bilirubin; total, conjugated, and
unconjugated.
ii. Urine – Bile pigments, bile salts and
urobilinogen.

12. Bilirubin
• Excretory product formed by the catabolism of heme.
• It is conjugated by the liver and excreted through bile
• Measurements of bilirubin as well as detection of
bilirubin and urobilinogen in urine are important tests of
liver function.
• Delta bilirubin: hepatic obstruction.

14. Clinical significane
• Van Den Bergh reaction
• diazotised sulfanilic acid (sulfanilic acid in HCl and sodium nitrite)
reacts with bilirubin to form a purple-colored complex, azobilirubin (
purple color)
• Indirect positive- hemolytic jaundice
• Direct positive – obstructive
• Biphasic- hepatic
• Neonatal: bilirubinometry device ( not in adult due to carotenoid
compounds)
• Special care should be taken for sample collection.

15. Bilirubin in urine –
• Fouchet’s tests
• Gmelin tests
Urobilinogen: Ehrlichs reagent ( p-dimethyl aminobenaldehyde)
Bile salts- Hays sulfurs test ( obstructive )

17. Liver enzyme panel
two groups: (a) Those indicating hepatocellular damage and
(b) those indicating cholestasis (obstruction).
i. Alanine amino transferase (ALT)
ii. Aspartate amino transferase (AST)
iii. Alkaline phosphatase (ALP)
iv. Gamma glutamyl transferase (GGT)
V. Lactate dehydrogenase (LDH) 4,5

18. Serum Transaminases
• Alanin transaminases-(ALT/SGPT)
• Aspartate transaminases-(AST/SGOT)
• Both involved in transamination reaction
• Indicate hepatocellular destruction:
• Even may go 100 times ( usually 10-40 times) of ULN
Normal value
ALT: 5-35 IU/L (Cytoplasmic)
AST: 5-40 IU/L( Both)

19. • In viral hepatitis and other acute hepatic necrosis, both
increases even before clinical sign and sympt ( Jaundice).
• ALT is mainly in liver ( less amount in skeletal and kidney) but
• AST is widely distributed equally in heart, skeletal muscle and liver.
• Makes ALT more specific to liver.

20. • High specific at cut-off limit of 10 x ULN ( acute; viral or drug
induced, or chronic such as autoimmune)
• Peak values between 7th and 12th days,
• normalizes by 3rd to 5th weeks.
• But, Persistence of increased ALT > 6mnths after an episode of
acute hepatitis: chronic hepatitis.
• Marked increase of mitochondrial AST in alcoholic liver damage and
necrosis occurs.

21. De Ritis ratio.
• Elevation of ALT is more in cases of hepatic disease compared to AST.
• But AST is more than ALT in alcoholic liver disease.
• AST/ALT >2 is quite suggestive of alcohol liver disease.
• De Ritis ratio.

23. Alkaline phosphatase
• Marker of obstruction
• Membrane bound glycoprotein
• Secreted by the cells lining the biliary canaliculi
• obstruction of bile with consequent irritation of epithelial cells leads
to secretion of ALP into serum.( mRNA translation increases rather
than transcription)
• Fnx: precise metabolic function is unknown, it appears that ALP is
associated with lipid transport in intestine and with calcification
process in bone.

24. Iso enzymes: ALP
• Liver, kidney, bones, placenta and intestine
• Normal range: 3-13 KA /dl ( 25-100 IU/l)
• 2-3 folds in hepatic disease
• 10-12 folds in obstructive jaundice
• Similar increase is seen in bone diseases like pagets, osteomalacia,
rickets, metastatic carcinoma of bone.
• Also, increase in pregnant woman.

25. Separation of ALP isoenzymes
 Electrophoretic mobility : intestinal>> bone>>placental and liver.
Phenylalanine inhibits: placental
 Stability to heat: after 56o for 15 min >> activity of other decreases
except placental.
• Liver reduced to 40% and bone to 15%

26. Gamma Glutamyl Transferase (GGT)
• membrane-localized enzyme in the kidney, liver, pancreas, intestine,
prostate but not in bone.
• GGT is a hepatic microsomal enzyme;
• therefore, ingestion of alcohol or certain drugs (barbiturates,) elevates
GGT.
• cholestasis caused by chronic alcohol or drug ingestion. alcohol abuse
• DIFFRENTIATE BETWEEN HEPATIC AND BONE DISEASE INCREASE OF
ALP
• 5-4O lU/L.

27. 5-Nucleotidase
• The serum activity of 5'-nucleotidase (normal 2-15 U/l) is elevated in
hepatobiliary disease and this parallels ALP.
• The advantage with 5'-nucleotidase is that it is not altered in bone
disease (as is the case with ALP)
• Others : Serum lactate dehydrogenase (LDH4 and LDH5) are also
useful in LFT

28. Plasma proteins
(Tests for synthetic function of liver)
i. Total proteins
ii. Serum albumin, globulins, A/G ratio
iii. Prothrombin time
iv. Special proteins

29. WHY protein is imp incase of
liver disease???
The concentrations of proteins in plasma
reflects
• the balance between availability of their precursors and rate of
synthesis, release and clearance.
• as well as their volumes of distribution,
• and it is therefore not surprising that in patients with liver disease
the levels are very variable.

30. Albumin
• Almost all the plasma proteins except immunoglobulin's are synthesized
by the liver.
• For Albumin : 100%
• Liver synthesizes about 12 g/ day.
• ½ half-life is about 20 days.
• Normal albumin level in blood is 3.5 to 5.5 g/dl;

31. • Since, albumin has a fairly long half-life of 20 days, in all chronic
diseases of the liver, the albumin level is decreased.
• A/G ratio : Reversed in case of cirrhosis, due to hypoalbuminemia
and associated hypergammaglobulinemia
• Normal: 1.5-2 : 1.
• Serum electrophoresis :
• Cirrhosis: Albumin level is decreases and gamma globulin level
increased

32. Some reasonable things
Other causes for LOW Albumin
• Malnutrition
• Excessive alcohol consumption
• Nephrotic syndrome
• Even rate of synthesis falls, because of compensatory reduction in
rate of degradation>>> plasma level in normal reference.
• Furthermore, hypoalbuminaemia >>> protein 'leaks‘ into lymph,
ascites or otherwise into the extravascular compartment.

33. Reference
• Total Protein : 6-8.3 gm/dl
• Albumin:3.5-5.5gm/dl
• Globulin:2.5-3.5gm/dl
• A/G: 1.5-2.5 gm/dl
• Ammonia: 10-20 μg/dl

34. Prothrombin time
• Defn : It’s the time which measures the rate at which prothrombin is
converted to thrombin in the presence of thromboplastin, calcium,
fibrinogen and other coagulation factors (V, VII and X).
• Vit K dependent activation : Prothrombin(II), VII, IX and X ( post
translational gamma carboxylation)
• Half life : 6hrs. ; therefore, PT indicates the present function of the liver.
• Normal: 10-15 sec.

35. TWO reasons for ⇑⇑ ed PT,
1) hepatic damage >>> impairs synthesis of the clotting factors
(vitamin К).
2) obstructive jaundice >>> impairs intestinal absorption of vitamin
K.
• PT is normalized by parenteral administration of vit. К (10 mg)
within 18 hours in obstruction jaundice ( supports
differentiation)
• Note : some patient ⇑⇑ ed PT due to dysfibrinogenemia , an
abnormal fibrinogen >>> doesn’t clot normally.

36. • NOTE: PT is controversial due to reagent composition between the
lab.
• Standardization by WHO : using ISI >> calculated INR.
• INR= (PT of patient/ PT of control)ISI( internation sensitivity index)
• Normal< 1.2
• Acute liver disease , recent damage to liver, in prognosis,
monitoring, and bleeding disorders.

37. Other proteins of interest
ALFA-FETOPROTEIN: Tumor marker
• Chronic hepatitis or cirrhosis: mild ⇧ed
• Hepatocellular carcinoma, germ cell tumors and teratoma of ovary:
drastic ⇧ed
• Neural tube defects : maternal serum ⇧ed
Α-Antitrypsin: acute phase protein
• Low levels: cirrhosis, and also in emphysema
Haptoglobin and Transferrin : The turn-over rates of are lesser
than albumin;
• to identify the recent changes in liver functions.

38. • CDT: alcohol consumption , best marker
• Alcohol >>> inhibit the glycation of transferrin and measurement of
desialylated transferrin >>>a marker of excessive alcohol abuse.
• Ceruloplasmin: The level is decreased in Wilson's
hepatolenticular degeneration.
• Decreased level in hepatic damage .

39. Galactose Tolerance Test: metabolic fxn
• The normal liver >> galactose into glucose; but this function is
impaired in intrahepatic diseases and the amount of blood
galactose and galactose in urine is excessive.
• 40 gm of galactose in oral administration
• Estimation of blood galactose over next 2 hour
• Normal : reach fasting level at 2 hrs
• Decrease in cirrhosis and hepatitis.

40. HIPPURIC ACID TEST: detoxification test.
• urinary bladder empty.
• About 6 g of sodium benzoate (250 ml water), is orally given,
• Urine collections (next 4 hours )
• hippuric acid excreted is estimated.
• In the healthy persons, about 60% of sodium benzoate (equivalent to
4.5 g hippuric acid) is excreted in urine.
• A reduction in hippuric acid excretion (particularly <3 g) indicates
hepatic damage

41. Bromsulphthalein Test: excretory
The ability of the liver to excrete certain dyes, e.g. BSP (through bile)
• BSP is given IV (5 mg/kg body weight)
• In serum: measured at 45 min and at 2 hrs.
• In normal: less than 5 % of the dye is retained
• liver disease : ⇈ed retention of the dye.
Damage liver cells fail to conjugate the dye

42. Autoantibodies:
• Antinuclear antibodies
• Double-stranded DNA
• Smooth muscle (actin) antibody
• Asialoglycoprotein receptor autoantibody
• Antimitochondrial antibody

47. • Types of bilirubin
• Pre, hepatic and post jaundice
• Urine : bile pigment, bile salt and urobilinogen
• Familial jaundice
• Neonatal physiological jaundice
• Phototherapy, kernicterus
• Standard liver function test.
• Albumin, globulin , A/G, PT
• Enzymes level ( Ecto and endo).
• Gilbert syndrome Test
• Heme degradation & Conjugation process
• Van den bergh reaction
• Cholesterol level in obstructive jaundice

50. Differentiation of Gilberts
• Normal reticulocyte counts ( increase in hemolytic )
• Haptoglobins and hemoglobin
• Total and unconjugated bilirubin increases: 1-3 mg/dl
• Monoglucoronide to diglucoronide ratio increased
• ALP/ALT /AST : NORMAL
• Urine bilirubin : negative
• liver histology is also normal
• Liver biopsy : staining of UGT is faint
• Nicotinic acid test +ve
• Calorie deprivation test + ve

51. Nicotinic acid test
• IV administration of nicotinic acid increases unconjugated bilirubin ( 2-3
folds with in 3 hrs)
• Over night fasting
• 500 mg of nicotinic acid is given IV
• Blood sample collected every 30 min ( for 3 hrs)
• Increases heme oxygenase activity of spleen and elevated osmotic
fragilty of RBCs.
• More RBCs lysis
• More unconjugated bilirubin.

52. Calorie deprivation test
• Reduced calorie intake for 3 days
• Increases lipolysis
• FFA binds to albumin
• Bound bilirubin gets detached
• Increase in unconjugated bilirubin ( 2-3 times)