The document discusses various liver function tests used to evaluate liver health and identify liver disorders. It describes tests that assess the liver's excretory, synthetic, and metabolic functions. Tests of hepatic excretory function include serum bilirubin and urine bile pigments. Markers of liver injury are ALT, AST, ALP, and GGT. Tests of synthetic function are serum albumin, globulins, total protein, and prothrombin time. Elevations in liver enzymes AST and ALT indicate liver cell damage, while increases in ALP and GGT can point to obstructive jaundice. Together, these tests provide a picture of liver function and identify causes of liver dysfunction.

1. LIVER FUNCTION TESTS
A SEMINER PREPARED
BY
LAWAL, BELLO DANCHADI
ADM NO: 22210705001
DEPARTMENT OF CHEMICAL PATHOLOGY AND IMMUNOLOGY
USMANU DANFODIYO UNIVERSITY, SOKOTO
MATCH, 2023

2. Introduction
LIVER
• Liver is the largest and most complex internal organ of the body.
• The weight of liver is about 1.5kg.
• It is located below the diaphragm in the right upper quadrant of the abdominal cavity.
• All blood flows from intestine and pancreas and reaches liver via portal venous system.
FUNCTIONS OF LIVER
Liver is a multifunctional organ that is involved in diverse body functions.
1. Metabolic Functions
• Liver actively participates in carbohydrate metabolism, lipid, protein, mineral and vitamin
metabolisms.
2. Excretory Functions
• Bile pigments, bile salts and cholesterol are excreted in bile into intestine.

3. FUNCTION OF LIVER CONT'D
3. Protective functions & detoxification
• Kuffper cells of liver perform phagocytosis to eliminate foreign compounds. For
example ammonia is detoxified to urea and
• metabolism of xenobiotics (detoxification).
• Clearance of hormones such as insulin,
• parathyroid hormone, oestrogen, cortisol
4. Hematological and synthetic functions
• Liver participates information of blood (particularly in embryo)
• Synthesis of plasma proteins (albumin and
• prothrombin), hormones e.g angiotensinogen, insulin-like growth factor and
triiodothyronine.
• Destruction of erythrocytes (Bilirubin).

4. 5. Storage functions
• Glycogen, vitamins A, D, E, K and B12
6. Production of bile salts
• Helps in digestion of fats
Liver Function Tests (LFTs)
• It is a non-invasive methods for screening of liver dysfunction
• Help in identifying general types of disorder
• Assess severity and allow prediction of outcome
• Disease and treatment follow up

5. Classification of LFTs
• Liver function tests are broadly classified into following groups according to their
functions:-
Group I —Tests of hepatic excretory function
i. Serum—Bilirubin; total, conjugated, and unconjugated.
ii. Urine—Bile pigments, bile salts and urobilinogen.
Group II—Markers of liver injury
i. Alanine amino transferase (ALT)
ii. Aspartate amino transferase (AST)
iii. Alkaline phosphatase (ALP)
iv. Gamma glutamyl transferase (GGT)

6. Group iii—Tests for synthetic function of liver
i. Total proteins
ii. Serum Albumin, Globulins, A/G ratio
iii. Prothrombin Time.
1. BILIRUBIN:-
• A by-product of red blood cell breakdown.
• It is conjugated by the liver to form bilirubin diglucuronide and excreted through bile.
• It is the yellowish pigment observed in jaundice
• High bilirubin levels are observed in: Gallstones, acute and chronic hepatitis.

7. PLASMA BILIRUBIN:-
• Normal plasma bilirubin: 0.2 – 0.8 mg/dL.
• Unconjugated bilirubin: 0.2 – 0.6 mg/dL.
• Conjugated bilirubin: 0 – 0.25 mg/dL.
• If the plasma bilirubin level exceeds 1mg/dL, the condition is called hyperbilirubinemia.
• Levels between 1 - 2 mg/dL are indicative of latent jaundice.
• When the bilirubin level exceeds 2 mg/dL, it diffuses into tissues producing yellowish
discoloration of sclera, conjunctiva, skin and mucous membrane resulting in jaundice.
• Icterus is the Greek term for jaundice.

8. Van den Bergh Test for bilirubin:-
• It is a specific test for identification of increased serum bilirubin levels.
• Normal serum gives a negative van den Bergh reaction.
Mechanism of the reaction:
• Van den Bergh reagent is a mixture of equal volumes of sulfanilic acid (in dilute HCL)
and sodium nitrite.
Principle:
• Diazotised sulfanilic acid reacts with bilirubin to form a purple colored azobilirubin.
Direct and indirect reactions:
• Bilirubin is insoluble in water while the conjugated bilirubin is soluble.
• Bilirubin shows direct, indirect and mixed reactions according to its unconjugated and
conjugated state.

9. • Van den Bergh reagent reacts with conjugated bilirubin and gives a purple colour
immediately (normally within 30 seconds).
• This is direct positive van den Bergh reaction.
• Addition of methanol (or alcohol) dissolves the unconjugated bilirubin and gives the van
den Bergh reaction (normally within 30 minutes) positive.
This is indirect positive van den bergh reaction.
• lf the serum contains both conjugated and unconjugated bilirubin in high concentration,
the purple color is produced immediately (direct positive) which is further intensified by
the addition of alcohol (indirect positive).
- This type of reaction is known as biphasic.

10. Van den berg test and Jaundice
• Useful in understanding the nature of jaundice.
• This is due to jaundice is characterized by increased serum concentration of unconjugated
bilirubin (hemolytic), conjugated bilirubin (obstructive) or both of them (hepatic).
• Indirect positive - Hemolytic jaundice
• Direct positive - Obstructive jaundice
• Biphasic - Hepatic jaundice.
Bilirubin in Urine:
• Normally bilirubin is absent in urine.
• Conjugated bilirubin being water soluble is excreted in urine in obstructive jaundice.
• This can be detected by Fouchet’s test

11. • In pre-hepatic jaundice, when the unconjugated bilirubin is increased in blood, it does
not appear in urine; hence called acholuric jaundice.
• In obstructive jaundice, urine contains bilirubin; hence in old literature, it is called
choluric jaundice.
Urobilinogen (UBG) and bile salts.
• Most UBG is metabolized in the large intestine but a fraction is excreted in urine (less
than 4 mg/day). Urobilinogen is detected by Ehrlich's test.
• Normally bile salts are NOT present in urine.
• Obstruction in the biliary passages causes: Leakage of bile salts into circulation,
Excretion in urine.
• Bilirubin cannot enter in to intestine

12. Note:
• Presence of bilirubin in urine and absence of urobilinogenin urine is seen in obstructive
jaundice.
• Increased urobilinogenin urine and absence of bilirubin in urine is seen in hemolytic
jaundice.
Fecal urobilinogen - Normal about 300mg.
• Increased in Hemolytic jaundice in which color of feces is dark.
• In Obstructive jaundice urobilinogenis not excreted through feces and the color is the
feces is pale.

13. Jaundice:-
Jaundice is yellow discoloration of conjunctiva , mucous membrane and skin due to increased
bilirubin level in the blood.
Clinical jaundice appears when bilirubin concentration is more than 3 mg/dL.
Levels between 1 and 3 mg/dL is sub-clinical jaundice.
Classification of Jaundice:
Jaundice is classified into three types
1. Pre-hepatic or he hemolytic Jaundice
2. Post-hepatic or obstructive Jaundice
3. Hepatocellular or hepatic Jaundice

15. TESTS BASED ON SYNTHETIC FUNCTION OF LIVER
SERUM ALBUMIN, GLOBULINS AND TOTAL PROTEIN AND A/G RATIO
• The most abundant protein synthesized by the liver.
• It constitute large portion of all plasma proteins approximately 50 to 60% and the rest
is Globulins.
• Help to maintain normal distribution of water in the body.
• Transport blood constituents eg. Ions, bilirubin, hormones, enzymes and drugs.
• Normal serum levels: 3.5 – 5.0 g/dL.
• Synthesis depends on the extent of functioning liver cell mass
• Longer half-life: 20 - 25 days
• Its levels decrease in all chronic liver diseases

16. Method of serum albumin estimation :
• Bromocresol Green (BCG)
Principle:
• Albumin bind with Bromocresol Green in an acidic medium to produced a blue-green
colored complex, the intensity of the color produced is directly proportional to the
concentration of albumin in the sample.
• Normal serum levels: 3.5 – 5.0 g/dL.
• Below 3.5 g/dL, the condition is called hypoalbuminemia caused by liver diseases,
malnutrition, malabsorption, diarrhea, genetic variation etc
• While above 5.0 g/dL (hyperalbuminemia) cause by dehydration and in some cases
vitamin A deficiency.

17. Serum Globulin
• Globulins are globular proteins with high molecular weight that albumin
• Insoluble in water but dissolved in dilute salt solution.
• Synthesized by the liver and immune system
• α and β-globulins mainly synthesized by the liver
• They constitute immunoglobulins (antibodies)
• Play a role in blood clotting and fighting infections.
• Normal serum levels 2.5 - 3.5 g/dL
• High serum γ-globulins are observed in chronic hepatitis and cirrhosis:
IgG in autoimmune hepatitis
IgA in alcoholic liver disease

18. Total protein
• Serum protein estimation yields most useful information in chronic liver disease.
• The liver is the site of albumin, fibrinogen and some of α and β-globulin synthesis.
• In advanced liver diseases, the albumin is decreased and globulin is increased so that
albumin-globulin ratio is reversed in liver cirrhosis.
• Serum proteins are decreased in malnutrition and liver damage.
• Low serum albumin is found in severe liver damage due to impairment ability of the
liver to form albumin.
• Reference range:

19. Prothrombin Time (PT)
• Prothrombin: synthesized by the liver, a marker of liver function
• Half-life: 6 hrs. (indicates the present function of the liver) “acute state”
• PT is the time required for the clotting to take place.
• PT is prolonged only when liver loses more than 80% of its reserve capacity.
• Increased PT may indicate liver damage but can also be elevated if you're taking
certain blood-thinning drugs, such as warfarin.
• Vitamin K deficiency also causes prolonged PT
• Intake of vitamin K does not affect PT in liver disease
• Normal range 9.4 to 12.5 seconds.

20. TESTS BASED ON SERUM ENZYMES
1. Alanine Amino Transferase
• ALT or SGPT (serum glutamate pyruvate transaminase)
• ALT is a cytoplasmic enzyme found in the liver,
• It help to convert alanine into pyruvate energy for cellular energy production.
• Normal Range: 10- 35 U/L.
• The test is primarily used to diagnose liver disease, to monitor the course of
treatment for hepatitis, active postnecrotic cirrhosis, and the effect of drug
therapy.

21. • ALT is more liver-specific than AST
• High serum levels in acute hepatitis (300 - 1000U/L)
• Moderate elevation in alcoholic hepatitis and nonalcoholic chronic hepatitis (100-
300U/L) .
• Minor elevation in cirrhosis, chronic hepatitis (50-100U/L)
2. Aspartate Aminotransferase (AST)
• AST or SGOT (serum glutamate oxaloacetate transaminase)
• AST is found in both cytoplasm and mitochondria
• It help to metabolize amino acids like ALT
• Also reflects damage to the hepatic cell
• It is less specific for liver disease
• It may be elevated and other conditions such as a myocardial infarct and muscle disease.

22. AST
• Normal range: 8 – 20 U/L
• A marker of hepatocellular damage
• High serum levels are observed in:- Chronic hepatitis, cirrhosis and liver cancer
3. Alkaline phosphatase (ALP)
• A non-specific marker of liver disease
• Produced by bone osteoblasts (for bone calcification)
• Present on hepatocyte membrane
• Normal range: 40 – 125 U/L
• Moderate elevation observed in:– Infective hepatitis, alcoholic hepatitis and
hepatocellular carcinoma
• High levels are observed in:– Extrahepatic obstruction (obstructive jaundice) and
intrahepatic cholestasis
• Very high levels are observed in:– Bone diseases

23. 4. γ-Glutamyl transpeptidase (GGT)
• It is a membrane bound glycoprotein which catalyses the transfer of γ- glutamyl group
to other peptides and AAS.
• GGT is used by the body to synthesize glutathione tri peptide.
• This is a microsomal enzyme widely distributed in body tissues, including liver.
• Very useful in diagnosis of obstructive jaundice. (not elevated in bone diseases)
• Normal range: 10 – 30U/L
• Moderate elevation observed in:– Infective hepatitis and prostate cancers
• GGT is increased in alcoholics despite normal liver function tests
• Highly sensitive to detecting alcohol abuse.
• In liver diseases, GGT elevation parallels that of ALP.
• In alcoholic liver disease, GGT levels may be parallel to alcohol intake

24. OTHER TESTS:-
• Tests based on metabolic capacity – Galactose tolerance, antipyrine clearance.
• Tests based on detoxification - Hippuric acid synthesis.
Special tests:
• Blood ammonia
• α1- antitrypsin
• Immunoglobulins
• Ceruloplasmin
• Ferritin