Liver Function Test

1. LIVER FUNCTION TEST
Dr. Khushboo Priya
DM Resident
Dept. of Gastroenterology

2. • Understand the major metabolic functions of the liver and
causes of liver dysfunction.
• Review interpretation of abnormal liver enzymes
• Develop an approach to managing elevated liver enzymes

3. Introduction
• Liver “Function” tests are a misnomer- not a true test of
function
• Abnormal LFTs are often the first indication of underlying
liver disease but normal results do not preclude significant
liver disease
• Sequential testing may allow assessment of the
effectiveness of therapy

4. Abnormal Liver Tests
• Laboratory determinations that reflect liver disease
commonly termed liver function tests
– Misnomer: elevated serum aminotransferase levels
and alkaline phosphatase levels are markers of liver
injury, not indices of degree of liver function.
• Measures of hepatic function: albumin, bilirubin,
prothrombin time
• Liver function tests are best referred to as liver biochemical
tests or liver chemistries.

5. • To identify liver disease
• To distinguish among types of liver disease
(hepatocellular, cholestatic/obstructive )
• To gauge the severity and progression of liver dysfunction
• To try and establish a specific diagnosis and identify
complications
• To monitor the response to treatment

6. Limitations
• Lack sensitivity
– Can be normal in certain serious liver conditions
• Cirrhosis, non-cirrhotic portal fibrosis , congential hepatic fibrosis
• Lacks specificity
– Not specific for any particular disease
• Serum albumin may be decreased in other conditions as well
• Aminotransferase can be raised in cardiac as well as hepatic diseases

7. What Constitutes a standard liver test?
• Various panels after reviewing the advantages and short
comings came up with what should be included in the
standard liver test.
• Most liver chemistries constitute of total serum bilirubin
(fractionated), serum aminotransferases(major), Alkaline
phosphatase, albumin, there has been an addition of GGT
in some places.
• Prothrombin time is sent along with the liver biochemical
tests In patients with suspected liver disease (ACG practice
guidelines)
.

8. – Complete history and physical examination to
identify the most common causes of mildly elevated
aminotransferase levels.
• Patient age and ethnicity;
• Presence of signs and symptoms of chronic liver disease
• Risk factors for viral hepatitis
• Presence of comorbid conditions like diabetes, obesity,
hyperlipidemia for NAFLD, neurologic manifestations in Wilson’s
disease (WD), emphysema in alpha-1-antitrypsin deficiency;

9. • History of alcohol consumption (including history from family),
medication use (especially new, careful review of available medical
and pharmacy records and laboratory data) and toxin exposure;
• Family history of genetic conditions pertaining to liver disease, such
as hemochromatosis and WD;
• History of chronic diarrhea or inflammatory bowel disease,
indicating extrahepatic causes like celiac sprue, thyroid disorders,
inflammatory bowel disease, hereditary and acquired muscle
disorders, etc.;
• Presence of signs and symptoms of heart failure, indicating
congestive hepatopathy;
• History of other autoimmune disorders (i.e. autoimmune hepatitis
(AIH)).

10. • Physical examination
– Stigmata of acute and chronic liver diseases which may be
subtle or absent
• Jaundice (with close attention to the conjunctiva and soft palate)
• Ascites
• Peripheral edema
• Hepatosplenomegaly
• Gynecomastia,
• Testicular hypotrophy
• Muscle wasting,
• Telangiectasias,
• Palmar erythema
• Pubic hair changes
• Some liver disorders like hemochromatosis and WD may be
associated with specific physical exam findings such as arthritis,
acne, skin color changes, Kayser–Fleischer rings, clubbing,
• Congestive heart failure would classically present with an
elevated jugular venous pressure, hepatomegaly and basilar

12. Metabolic
function
Excretory
function
Synthetic
function
Detoxification
function
Storage
function

13. According to function of liver
Tests based on
excretory function
Tests based on metabolic
function
Tests based on
detoxification function
Tests based in
storage function
Tests based on
synthetic function

14. 1.Serum bilirubin
2.Urine bilirubin
3.Urine and feacal urobilinogen
4.Urine bile salts
5.Dye excretion tests
TESTS BASED ON EXCRETORY FUNCTION

15. Hippuric acid
test
Determination
of blood
ammonia
TESTS BASED ON DETOXIFICATION
FUNCTION

16. Plasma
proteins
Prothrombin
time
TESTS BASED ON SYNTHETIC
FUNCTION

17. Tests related to
CARBOHYDRATE
metabolism
Tests related to
LIPID
metabolism
Tests related
to PROTEIN
metabolism
Galactose tolerance
test
Serum cholesterol Serum proteins
Aminoaciduria
TESTS BASED ON METABOLIC FUNCTION

18. ENZYMES IN DIAGNOSIS OF LIVER DISEASE
SERUM
TRANSAMINASES
AST
ALT
AL
P
GG
T
5’

19. Heme oxygenase
Biliverdin reductase
Hemoglobin
(70to 80%) Erythroid cells
Heme proteins
myoglobin, cytochromes
(20to 25%)
Biliverdin
Bilirubin
NADPH + H+
NADP+
Heme
(250to 400mg/day)
3 [O]
Fe3+ + CO
apoferritinferritin
Indirect
unconjugated
pre-hepatic
albumin

20. albumin-Bilirubin
ligandin
Bilirubin diglucuronide
ER
hepatocyte
UDP-Glucuronyl
transferase
bile (gall bladder)
direct
conjugated
post-hepatic
ligandin-Bilirubin
2UDP-glucuronate
2UDP

21. Bilirubin diglucuronide
Stercobilinogen
Bacterial enzymes
Bilirubin
Bacterial enzyme2glucuronate
Bacterial enzyme
Urobilinogen
liver
Intrahepatic
urobilinogen
cycle
Urobilin
kidneys
urine
Stercobilin Feces
kidneysIntestines
Beta glucuronidases

22. 1. Serum bilirubin

23.  Total bilirubin 1.0 – 1.5 mg/dL
 Indirect bilirubin – 0.8-1.2 mg/dL (diazo method over estimates
direct bilirubin
 If direct bilirubin is <15% of total bilirubin then bilirubin is
indirect/unconjugated.
 Upper limit of normal value of direct bilirubin – 0.3mg/dL
 If the plasma bilirubin level exceeds 1mg/dl, the condition is
called hyperbilirubinemia.
 Levels between 1&2mg/dl are indicative of
latent jaundice.

24.  When the bilirubin level exceeds 2mg/dl, it
diffuses into tissues producing yellowish
discoloration of sclera, conjunctiva, skin &
mucous membrane resulting in jaundice.
 Icterus is the Greek term for jaundice.

25. Van Den Bergh reaction
Serum bilirubin Diazotized sulphanilic acid
(Ehrlich diazo reagent)
Azobilirubin( purple)
Direct positive
Direct bilirubin – reading is taken at 30-60 secs
Add activator
methanol/accelerator
2nd reading at 30-60 minutes – Total bilirubin
Indirect Positive

26. • Delta bilirubin – conjugated bilirubin tightly linked to
albumin through covalent binding
–Identified by new methods like liquid chromatography
–Has a half life similar to albumin (14-21 days) compared
to serum bilirubin (4hours)
–Seen in prolonged and severe elevation of serum
conjugated bilirubin

27. Direct Bilirubin
• conjugated
• water soluble
• polar
• seen in urine
• elevated with biliary
obstruction and
hepatocellular disease.
Indirect Bilirubin
•unconjugated
•lipid soluble
•non-polar
•not in urine
• Elevated with hemolysis,
hepatic disease

29. • Magnitude and duration of
hyperbilirubinemia has not been critically
assessed as prognostic markers.
• The higher the serum bilirubin level in
patients with hepatitis, the greater the
hepatocellular damage and longer the
course of disease
• Total bilirubin correlates with poor outcome
in alcoholic hepatitis and critical
component of MELD score (used to
estimate survival in ESLD)

30. TYPES OF JAUNDICE
PRE HEPATIC HEPATIC POST HEPATIC
Excessive amount of
bilirubin is presented
to the liver due to
excessive hemolysis
Impaired cellular
uptake, defective
conjugation or
abnormal secretion
of bilirubin by the
liver cell
Impaired excretion due
to mechanical
obstruction to bile flow
Elevated
unconjugated bilirubin
in serum
Both conjugated and
unconjugated
bilirubin may be
elevated in serum
Elevated conjugated
bilirubin in serum

31. TYPES OF JAUNDICE
PRE
HEPATIC
HEPATIC POST
HEPATIC
Hemolytic Hepatitis, Gallstone,
Anemia cirrhosis, Crigler- malignancy,
Najjar Syndrome, inflammation
Dubin-Johnson
Syndrome,
Rotor’s
Syndrome

33. Causes of isolated hyperbilirubinemia

35. Evaluation of Isolated Hyperbilirubinemia

36.  The conjugated bilirubin is water soluble & is
excreted in urine.
 Unconjugated bilirubin always binds to albumin in
the serum and is not filtered by the kidney. .
 Bilirubin in urine can be detected by Fouchet's
test or Gmelin's test
 In patients recovering from jaundice, the
urine bilirubin clears prior to the serum
bilirubin.

37. • Increase in urine is sensitive indicator of hepatocellular
disease
• It is markedly increased in hemolysis
• Viral hepatitis (appears early )
• In cholestatic jaundice urobilinogen disappears from urine
• Gallstones – intermittently present
• Urine strips are available
• Fresh urine should be used
•Ehrlich’s test – gives pink-red color

38. •Products of cholesterol metabolism
•Facilitate absorption of fat from intestine
•Constitute a substantial amount of bile in bilirubin
excretion and can be used in diagnosing cholestasis
•Primary bile salts – cholate and
chenodeoxycholate are produced in liver
Metabolised by bacteria in intestine

40. •In normal condition – renal excretion of bile salts is
negligible
•In cholestasis – increased renal excretion of bile salts
•
•For measuremnet – chromatography (HPLC)
•Hay’s test – bile salts when present lower the surface
tension of urine
•When sulphur powder is added to the urine, sulphur
particles sink to the bottom of the tube
•In case of normal urine,
it will float on the surface

41. Hippuric acid
test
Determination
of blood
ammonia
TESTS BASED ON DETOXIFICATION
FUNCTION

42. BLOOD AMMONIA
•Produced in body by normal protein metabolism and by
intestinal bacteria
•For detoxification of ammonia
In liver
converted to urea
Excreted by kidneys
In striated muscles
Combines with glutamic acid
Forms glutamine

43. Plasma
proteins
Prothrombin
time
TESTS BASED ON SYNTHETIC
FUNCTION

44. PROTEIN
•Liver is the sole site for synthesis of most plasma proteins
except immunoglobulins (gamma globulins)
•Serum albumin comprises 60% of all plasma proteins
TESTS FOR PROTEINS INCLUDE-
1. Total serum proteins
2. Serum albumin
3. Sr albumin/globulin ratio
4. Serum protein electrophoresis
5. Prealbumin
6. Procollagen III peptide
7. Ceruloplasmin
8. Alpha fetoprotein
9. Alpha antitrypsin

45. Biuret Test:Liver Function TestsBasedUpon ProteinMetabolism

46. SerumProteinsin normal andabnormalliver function(dysfunction
Serum protein type Concentration ( physiological
)
Total serum protein 6.5-7.5gm%
Serum albumin 3.5-5gm %
Serum globulin 2.5-3.5gm %
Serum fibrinogen 200-500 mg%
Albumin /globulin(A/G  2:1 to 1.5: 1
Chronic liverdiseases  Serum albumin (half life 2 days 
decreases Cirrhosis  hypoalbuminemia and
hyperglobulinemia A/G decreases

47. Serumglobulins
• Serum globulins : constitute immunoglobulins
• Immunoglobulins : produced by beta lymphocytes
• Alpha and beta globulins : synthesized by hepatocytes
• Gamma globulins in serum : increased in Cirrhosis ,chronic
active hepatitis
immunoglobulin Normal levels serum (mg/dl 
IgG 7- 16
IgM 4-23
IgA 7-4
IgD  -8
IgE -3.8 microgram /dl

48. Serumglobulins in liverdiseases
• Gamma globulins in serum : increased in Cirrhosis ,chronic
active hepatitis
Liver disease Increased levels of
serum
Auto immune hepatitis IgG
Primary Biliary Cirrhosis IgM
Alcoholic liver disease IgA

49. ALBUMIN
•Synthesized exclusively by liver
•Its half life is 18-20 days
•Due to its slow turn over – not a good indicator of
acute or mild hepatic dysfunction
•In hepatitis - <3g/dl of albumin – possibility of
chronic liver disease
•Non hepatic causes of Hypoalbuminemia -
• Protein losing enteropathy
• Nephrotic syndrome

50. 2. Prothrombin time
• Measure of clotting tendency of blood and due to the clotting
factors produced by the liver (II,V,VII,IX,X) depicting the
extrinsic pathway of coagulation
• INR standardises the prothrombin time measurement
according to the characteristics of thromboplastin reagent
(using International sensitivity index ISI) to calculate INR
– Since ISI is validated only in patients taking vitamin K antagonist
so use in CLD is still questionable

51. • Prolonged prothrombin time
– Hepatocellular dysfunction (hepatitis, cirrhosis, acute liver failure)
– Congenital deficiency of clotting factors
– Patients taking vitamin K antagonists
– Vitamin K deficiency esp in cholestasis
– DIC
– Hypothermia

52. • Factor VII has a short half life of 6 hours and
fibrinogen 5 days
• Most sensitive marker of liver function as it is
prolonged within 24 hours duration of liver disease
– Most useful in acute liver failure
• Component of MELD and CTP score
• Not an accurate measure for bleeding risk in
patients with cirrhosis as it assesses only pro
coagulant factors and not anti thrombin or protein
C which decrease in cirrhosis
• In the absence of liver disease, if it is prolonged
– Suspect vitamin K deficiency or steatorrhoea

53. PREALBUMIN /TRANSTHYRETIN
• Levels fall in liver disease
• Half life – 2 days
• Sensitive indicator of any changes affecting its
synthesis and catabolism
• PAB is a negative acute phase reactant
• Particularly useful in drug-induced
hepatotoxicity

54. • Normal plasma levels - 0.2-0.4g/L
• Acute phase protein
• Decreased in multiple conditions –
1. Wilson’s disease
2. Menkes disease
3. Aceruloplasminemia
4. Copper deficiency
CERULOPLASMIN
Increased in –
1. Copper toxicity
2. Pregnancy
3. OCPs

55. PROCOLLAGEN III PEPTIDE
• Cleavage product of the type III procollagen
molecule
• Radioimmunoassay
• Elevated Conc. Of PIIIP- the transformation of
viable hepatic tissue into connective
tissue/fibrosis

56. • AFP is a gp and MW – 70,000 daltons
• Normally present in fetus
• Liver, yolk sac and small intestine
• AFP- ELISA
HCC
Non seminomatous testicular cancer
Ataxia telangiectasia
Hereditary tyrosinemia
Neonatal hyperbilirubinemia
Chronic active hepatitis
α- FETO PROTEIN

57. Alpha -1 antitrypsin(AAT
Alpha-1 antitrypsin (AAT :
1. Synthesized and secreted by liver
2. Major function : inactivates proteases ( elastase and
collagenase 
3. has got multiple alleles
4. PiZZ allele: characterized by
defective enzyme activity prone for developing
liver cirrhosis
5. Normal serum Alpha -1 antitrypsin (AAT : 9-2 mg/dl (.9-2
g/L 

59. 1.Enzymes whose elevation reflects damage to
hepatocytes
2. Enzymes whose elevation reflects cholestasis
3. Enzyme test that do not fit into either pattern
• ENZYMES WHOSE ELEVATION REFLECTS DAMAGE TO
HEPATOCYTES
• AMINOTRANSFERASES (transaminases) –
They include AST and ALT
SERUM EMZYME TESTSARE
GROUPED IN 3 CATEGORIES

60. • Also called transaminases
• Most sensitive marker of hepatocellular injury
• Increase in serum values indicate either damage to the tissues rich in
these enzymes or changes in cell membrane permeability that allow
AST and ALT to leak into serum
• Hepatocyte necrosis is not required for the release of these enzymes
so the degree of elevation doesn’t correlate with the extent of
liver injury
• ALT ( Alanine transaminase / serum glutamic pyruvic transaminase)
• AST (Aspartate Trasaminase/ serum glutamic oxaloacetic
transaminase)

61. • AST(SGOT) – found in liver> cardiac muscle > skeletal
muscle> kidneys >brain
• ALT(SGPT) – found primarily in liver
• Normally present in serum in low concentration
(Male-30 IU/L; Female-19 IU/L)
• When there is damage to liver cell membrane –
increased permeability and so increased serum
concentration
• Liver cell necrosis is not required for release of these
enzymes

62. •Levels of >1000 IU/L occurs in –
• Acute viral hepatitis
• Toxin and drug induced hepatitis
• Ischaemic liver injury
• In most acute hepatocellular disorders ALT is higher or
equal to AST

63. • Normal ratio is 0.7 to 1.4
• Useful in Wilson disease, chronic liver disease
and alcoholic liver disease
• AST/ALT ratio of > 2:1 is suggestive of and >3:1
is highly suggestive of ALCOHOLIC liver disease
• AST in Alcoholic live disease is rarely >300 IU/L
AST/ALT RATIO

64. • ALT is usually normal in alcoholic liver disease ; can
be sometimes low due to an alcohol induced
deficiency of pyridoxal phosphate
• AST/ALT <1 is seen in NASH and viral hepatitis

66. •Determination of these enzymes are helpful in
distinguishing hepatocellular from cholestatic
jaundice
•Increase in AST and ALT is much more ( >500 IU/L)in
hepatocellular jaundice than in cholestatic jaundice
(>200 IU/L)
•Persistence of elevated ALT and AST beyond 6
months in a case of hepatitis indicates development
of chronic hepatitis

67. Approach to asymptomatic elevated
aminotransferases

71. 3 enzyme activities are important –
1. Alkaline phosphatase (ALP)
2. 5’nucleotidase (5’NT)
3. Gamma glutamyl transferase (GGT)
ENZYMES WHOSE ELEVATION
REFLECTS CHOLESTASIS

72. Alkaline phosphatase (ALP)
•ALP – found in liver , bone , placenta and small intestine
•Physiological increase in ALP is seen in –
1.>60 yrs
2.Pregnancy
3.Blood groups O and B – after fatty meal influx of intestinal ALP
into blood
4. In children and adolescent during rapid bone growth
• ALP >4 times the Normal is seen in –
1. Cholestatic liver disease
2. Infiltrative liver disease such as cancer and amyloidosis

74. Low ALP
• Wilson’s disease presenting with fulminant hepatic failure
• Hemolysis
Due to reduced activity of the enzyme owing to
displacement of cofactor zinc by copper

76. GGT
• Found in cell membrane of hepatocytes and cholangiocytes, kidney,
pancreas, spleen, heart, brain and seminal vesicles
• Elevated in patients consuming alcohol, those taking phenytoin,
barbiturates, drugs used in HAART (PI and NNRTI)
– Sensitivity in alcohol consumers – 52-94% but low specificity
• Not elevated in pregnancy and bone disease so it can help in
differentiating liver origin of ALP
• Raised GGT is risk for developing HCCand isolated rise is
associated with increased mortality in metabolic syndrome, DM and
cardiovascular diseases

77. 5’- Nucleotidase

78. Serum γ-Glutamyl Transferase
• Normal range: 10-47 IU/L
Serum 5’-Nucleotidase
• Normal range: 2-17 IU/L
Serum alkaline phosphatase
• Normal range: 39-117 IU/L

80. The Fibrotest (Fibrosure in the USA) is the most
widely validated indirect serum marker panel,
extensively studied. It is computed using five
parameters, namely total bilirubin, haptoglobin,
gamma-glutamyl-transpeptidase, ᾳ2-macroglobulin
and apolipoprotein-A1.
 Transient elastography (TE)/Fibroscan
 Ultrasound elastography
 MR elastography

82. Special applications of liver
biochemical test

83. Drug induced liver injury
• Most drugs cause idiosyncratic liver injury
– Injury that is unpredictable, occurs at therapeutic drug level and is infrequent
• Drug induced liver injury occurs in 1 in 1000 to 1 in 100,000
• Variable latency period ranging from days 5-90 days or even longer
• Some drugs produce dose dependent liver injury which are predictable and
have a high incidence
– E.g – Acetaminophen
• Most patients respond to withdrawl of drug and have mild elevations only
• Isolated elevation of aminotransferases >3 times the ULN may have good
outcome after withdrawl
• If associated with clinical jaundice, the risk of mortality increases as high as
10%
• It is better to send for liver function test before starting medications
suspected to cause liver injury and withdraw the drug once liver injury
occurs

85. • High risk of morbidity and mortality in acute or chronic liver disease
undergoing surgery
• Risk mainly depends on the etiology of the disease, severity of the
disease and planned operation
• If abnormality found during pre-operative LFT in otherwise healthy
individual, the surgery should be postponed till the cause is identified
• Various studies found that in acute viral hepatitis who undergo
surgery, the operative mortality rate is nearly 9.5%
• Patients with chronic hepatitis with portal inflammation and interface
hepatitis have low operative risk compared to panlobular hepatitis
• Hepatic steatosis has low operative risk compared with alcoholic
hepatitis (55%)
• Abstinence of 3-6 months is required before elective surgery
• In NAFLD, operative risk increases with steatohepatitis

86. • Surgical risk is evaluated using Child-Pugh score
– Studies done evaluated a risk of 10%, 30-31% and 76-82% in
CTP A,B,C in patients undergoing abdominal surgery
– CTP A – surgery may be undertaken
– CTP B – surgery should be done only after medical condition is
optimized
– CTP C – surgery should be avoided

88. Conclusion
• Interpretation of laboratory values in patients with
abnormalities in liver panel testing is critical to developing
a differential diagnosis and initiation an adequate work-up
• The initial step is determination of an acute, chronic, or
acute-on-chronic process

89. Conclusion
• Acquisition of histology can be used to confirm a
suspected diagnosis, rule out hepatic disease, and stage
the degree of fibrosis
• Upon establishment of chronicity, the role of the
practitioner is to establish the severity of hepatic
dysfunction, potential for reversibility, and the need for
escalation of care

90. References
• AASLD Guidelines 2019
• Harrison’s Principles of Internal medicine
20th edition
• Sleisenger and fordtran's gastrointestinal
and liver disease 11th edition