Liver function tests (LFTs) are a group of blood tests that can help diagnose and monitor liver disease. The liver performs many vital processes and LFTs evaluate liver health by measuring biomarkers related to the liver's excretory, synthetic, and metabolic functions. LFTs are classified into 5 groups: 1) tests of excretory function like bilirubin, 2) tests of synthetic function like albumin and prothrombin time, 3) serum enzymes indicating liver cell damage or cholestasis, 4) tests of metabolic function, and 5) markers of hepatic fibrosis. While LFTs provide a noninvasive way to screen for liver dysfunction, they lack specificity and sensitivity for diagnosing

1. LIVER FUNCTION TESTS
DR SUNNY CHOPRA

2. LFT’S
 ……..Group of biochemical tests used for diagnosis
and monitoring of liver disease
 Hepatic Physiology:
 Largest solid organ in the body
 Performs over 500 chemical processes
 Produces over 160 different proteins

5. BASIC PROCESSES IN LIVER DISEASES
• Acute &Chronic
Hepatitis
• Cirrhosis
Liver cell
damage
• Intra hepatic
cholestasis
• Extra hepatic
cholestasis
Biliary tract
involvement

6. CLASSIFICATION OF LFT’S
Group 1
• Tests based on Excretory Functions
Group 2
• Tests based on Synthetic Functions
Group 3 • Tests based on Serum Enzymes
Group 4
• Tests based on Metabolic Functions/ Special tests
Group 5
• Markers of Hepatic fibrosis

7. GROUP 1- TESTS BASED ON EXCRETORY
FUNCTIONS
 SERUM- Total bilirubin, conjugated and un-
conjugated bilirubin
 URINE – Bile pigments, bile salts and urobilinogen

9. ESTIMATION OF BILIRUBIN

10. GROUP 1- ESTIMATION OF BILIRUBIN
 Serum Bilirubin:
Total bilirubin: 0.2–1.0 mg/dl
Conjugated bilirubin: 0-0.4 mg/dl
Un-conjugated bilirubin: 0.4-1.0mg/dl
Jaundice > 2mg/dl
(Serum bilirubin is elevated, when excretion
capacity of liver is decreased to 50%)

11. GROUP 1- URINE FINDINGS
 Urinary - Bilirubin & Urobilinogen
 Pre-Hepatic/ Hemolytic jaundice:
Urobilinogen ++
Bilirubin -- (acholuric jaundice)
 Obstructive jaundice:
Urobilinogen --
Bilirubin ++ (choluric jaundice)

12. GROUP 1- FECES FINDINGS
 Bilirubin in feces: Normally not present.
 Fecal Urobilinogen : 50-250mg/day
 Hemolytic jaundice - Dark colored feces
 Obstructive jaundice– Clay colored feces
 Malignant obstruction- Complete absence of fecal
Urobilinogen

13. Findings Hemolytic
jaundice
Obstructive
jaundice
Hepatocellular
jaundice
Total Bilirubin Elevated Elevated Elevated
Conjugated
Bilirubin
Normal Elevated Elevated
Unconjugated
Bilirubin
Elevated Normal Elevated
Bile pigments
(urine)
Absent +++ ++
Bile Salts
(urine)
Absent ++ +
Urobilinogen
(urine)
Elevated Absent Normal or less

14. BROMOSULFTHALEIN (BSP)TEST
(EXCRETORY FUNCTION)
 Very Sensitive Test
 Single bolus dose of BSP – 5mg/kg bw
 Serum concentration at 25 mtns and 45
mtns are measured
 Normal cases – retention is <5% at 45 mtns
 Increased retention - Useful to detect mild
impairment/ index of Liver damage
 (Contraindication - Obstructive jaundice)

15. GROUP-2
TEST BASED ON SYNTHETIC FUNCTIONS
1. Serum Total proteins: 5.5 - 8.0 g/dl
2. Albumin: synthesized exclusively in liver
 3.5 - 5.0 g/dL (Half-life:15-20 days)
Impaired synthesis in hepatic dysfunction, (cirrhosis-
<3.0g/dl)
 severity of hypoalbuminemia α degree of damage
 Low albumin after treatment is poor prognostic sign

16. GROUP-2
TEST BASED ON SYNTHETIC FUNCTIONS
3. Globulin: gamma globulin levels increased in
chronic conditions of liver
4. A:G Ratio : 1.5-2.5
reversed in cirrhosis
 Severity of Hypoalbuminemia α Degree of damage
 Low albumin after treatment is poor prognostic
sign

17. GROUP-2
TEST BASED ON SYNTHETIC FUNCTIONS
5. Prothrombin Time:
 Except factor VIII, all Clotting factors are
synthesized by liver
 PT collectively measure factor II, V, VII and X.
 10-13 sec
 Time increased in acute and chronic liver diseases
(Vit K should normal)

18. GROUP-3
TESTS BASED ON SERUM ENZYMES
1. Enzymes indicating Hepatocellular
damage (ALT, AST)
2. Enzymes indicating Cholestasis (ALP,
GGTP,5’NT)

19. GROUP-3 (ALT/SGPT)
 More liver specific enzyme
 Half-life 47hrs
 Present in cytosol of hepatocytes and
released with mild cell damage (necrosis),
inflammation (hepatitis), drug toxicity.
 Normal range: 5-40 U/L
 Decrease levels indicates response to
treatment and good prognosis.

20. alanine -ketoglutarate pyruvate glutamate
Aminotransferase (Transaminase)
COO
CH2
CH2
C
COO
O
CH3
HC
COO
NH3
+
COO
CH2
CH2
HC
COO
NH3
+
CH3
C
COO
O
+ +

21. GROUP-3 (AST/ SGOT)
 Found in heart, liver, muscle, intestine,
pancreas
 Not very specific for liver disease
 Normal range: 5- 30 U/L
 In liver 20% activity is cytosolic and 80%
mitochondrial
 Elevated 2 or 3:1 (vs. ALT) in alcoholics

22. (AST/ SGOT)
aspartate -ketoglutarate oxaloacetate glutamate
Aminotransferase (Transaminase)
COO
CH2
CH2
C
COO
O
COO
CH2
HC
COO
NH3
+
COO
CH2
CH2
HC
COO
NH3
+
COO
CH2
C
COO
O
+ +

23. AST/ALT RATIO (0.8)
 < 1 : liver disease
 >2
 Extra-hepatic source
 Alcoholic hepatitis
 Liver metastasis
 MI
 Erythromycin treatment
 >4 : fulminant Wilson’s disease

24. GROUP- 3
(ALKALINE PHOSPHATASE)
Markers of Cholestasis
 ALP – liver and bone (placenta, kidneys,
intestine, breast)
 Normal Range: 3-13 KAU/dl, 40-125U/L
 Moderate increase 2-3 times - hepatic
disease
 High levels (10-12) - extra or intra hepatic
obstruction
 V high levels (10-25) - bone disease

25. GROUP 3 (GGT)
 catalyzed transfer of γ-glutamyl groups of
peptides to other amino acid
 11 isoenzymes, abundant in liver, kidney,
pancreas, intestine, and prostate, spleen, heart,
brain but not in bone
 Normal range: 10-30U/L
 Along with ALP …good marker of cholestasis

26. GROUP 3 (GGT)
 T1/2
 7-10 days (28 days in alcohol-associated
liver injury)
 Very sensitive to detect alcohol abuse
 GGT levels in alcoholic liver disease parallels
alcohol intake

27. GROUP-4
TESTS BASED ON METABOLIC FUNCTIONS
 Estimation of iron profile:
serum iron
serum ferritin
Galactose tolerance test
Fructose tolerance test

28. GROUP-4
TESTS BASED ON METABOLIC FUNCTIONS
 Galactose tolerance test:
 Basis: Normal Liver is able to convert Galactose
into glucose
 Procedure: 40 gm orally or 0.5 gm/kgBW I/V is
given
 Blood samples are collected at ½ hr intervals
 Interpretation: 3gm or less Gal is excreted in urine
& normal gal in serum
 Parenchymatous disease: Excretion is more
 Can be done in Jaundice

29. GROUP- 4
TESTS BASED ON METABOLIC FUNCTIONS
 Fructose tolerance test
 Epinephrine tolerance test :
 Principle: Response to epinephrine is evidenced
by elevation of Blood sugar and is directly
influenced by Glycogen stores of liver
 Interpretation: Parenchymal and Glycogen storage
disease

30. GROUP- 5
MARKERS OF HEPATIC FIBROSIS
1.Direct Markers
 SHA (serum hyaluronic acid)
 PICP(procollagen type carboxy terminal peptide
 MMP (matrix metalloproteinases)
2. Indirect Markers
 AST/ALT ratio
 Platelet count
 Apolipoprotein A1

32. Advantages
• sensitive, noninvasive
method of screening liver
dysfunction
• pattern of laboratory test
abnormalities to recognize
type of liver disorder
• assess severity of liver
dysfunction
• follow cause of liver
disease
Disadvantages
• lack sensitivity
– normal results in serious
liver disease
• not specific for liver
dysfunction
• seldom lead to specific
diagnosis
LIVER FUNCTION TEST

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