Liver function test

1. LIVER FUNCTION TEST
SHUBHAM KUMAR MAURYA

2. Liver Function test
• Liver function test (LFT) includes a group of blood tests commonly
performed to evaluate the function of the liver. This test measures
the level of enzymes and proteins produced by the liver
including bilirubin, albumin, lactate dehydrogenase etc. It is advised in
case of symptoms suggestive of liver problems such as dark urine,
diarrhoea, light stool and jaundice.
• LFT helps in the diagnosis of liver related conditions including liver
cirrhosis, hepatitis and liver damage. It is also advised to patients
undergoing treatment for liver disorders.

3. Liver function test
Test for bilirubin
Direct bilirubin
Indirect bilirubin
Test for Liver enzymes
Test for plasma protein

4. Bilirubin
• Bilirubin is the result of the catabolism of haemoglobins. Structurally,
it is an open-chain tetrapyrrole. The porphyrin rings in the
haemoglobin are cleaved in the red blood cells by oxidation, and
biliverdin is obtained as the product. The biliverdin is then reduced to
bilirubin. It is predominantly found in the liver.
• The chief role of bilirubin is as a cellular antioxidant. It prevents
toxicity in the brain by scavenging free superoxide molecules.
• The bilirubin exists in two forms in the liver: direct bilirubin and
indirect bilirubin.

5. Direct Bilirubin
Direct bilirubin, also known as conjugated bilirubin, is the modified form of the product
obtained after the catabolism of haemoglobin.
The bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase.
This conjugation makes the direct bilirubin less toxic and easy to excrete. Direct
bilirubin is soluble in water.
The total bilirubin of our body is the sum of direct and indirect bilirubin. Normal bilirubin
values for adults are:
Total bilirubin: 0.3 to 1.9 mg/dL
Direct bilirubin: 0.0 to 0.3 mg/dL

6. Indirect Bilirubin
Indirect bilirubin, also known as unconjugated bilirubin, is the direct product of the
breakdown of haemoglobin. The unmodified bilirubin binds to albumin, facilitating easy
transport from blood to the liver.
However, this form of indirect bilirubin is highly toxic; therefore, it is converted to direct
bilirubin in the liver with the help of enzymes, which is less toxic.
Indirect bilirubin is highly soluble in lipids and is lipophilic. It is, however, insoluble in
water.
Higher levels of bilirubin can be caused due to several reasons such as,
Haemolytic anaemia, a condition where our body starts getting rid of too many RBCs.
Bleeding in skin due to some injury.
Bleeding in the lungs
Genetic malfunctioning.

7. Jaundice
Jaundice is a disease that causes the yellowish discolouration of the skin, sclerae
(white part of the eye) and other mucous membranes. Additionally, body fluids may
also change to yellow colour. Technically, it is also called as icterus.

8. Types of jaundice
Hemolytic Jaundice: It occurs when erythrocytes or red blood cells break down at an
accelerated rate, resulting in the buildup of more bilirubin. This occurs due to infectious
diseases such as malaria, anemia etc.
Hepatocellular jaundice: It occurs as a result of liver damage or injury. The
liver generally gets damaged due to infections, excessive consumption of
alcohol and also due to parasitic infections.
Obstructive Jaundice: This occurs when bilirubin is blocked and is unable to
be discharged from the liver.

9. Direct vs Indirect Bilirubin
Direct Bilirubin Indirect Bilirubin
Description
Direct bilirubin is the conjugated form of bilirubin
that is obtained as a catabolism product of
haemoglobin.
Indirect bilirubin is the direct product of the
catabolism of haemoglobin.
Solubility
Highly soluble in water. Highly soluble in lipids.
Toxicity
It is less toxic to the human body. It is very toxic to the human body.
Protein Carrier
It does not require any protein carrier for
transportation.
It binds to albumin for transportation from blood to
the liver.

10. Haemoglobin
Haem(Iron)+ Globin (Protein)
Haem breakdown in Iron and Porphyrin
Porphyrin
Biliverdin
Unconjugated bilirubin (indirect bilirubin ) water insoluble
Blood protein (Albumin ) + UCB
Liver (UCB +Uridine glucuronyl transferase )
Conjugated bilirubin (Direct bilirubin) water soluble
Stored in gallbladder or pass though the duodenum
metabolized by normal intestinal bacteria to urobilinogen
99% urobilinogen convert in stercobilinogen pass though stool
1% Urobilinogen enter in blood and excreted by kindey in form of urine

11. Liver enzymes test
• Liver enzymes are proteins that speed up chemical reactions in your
body. These chemical reactions include producing bile and
substances that help your blood clot,breaking down food and
toxins,and fighting infection.Common liver enzymes include:
• Alkaline phosphatase (ALP).
• Alanine transaminase (ALT).
• Aspartate transaminase (AST).
• Gamma-glutamyl transferase (GGT).

12. Alanine aminotransferase (ALT)
1.This enzyme catalyses the reversible transfer of amino groups
between an amino acid, and α-keto acids are called aminotransferase
or transaminases.
2.One of the aminotransferases is Alanine aminotransferase (ALT), or
the old name was serum glutamate-pyruvate transaminase (SGPT)
which will catalyse the reversible transfer of the amino group
between an amino acid and α-keto acid where vitamin B6 (pyridoxal
phosphate) is the co-factor.

13. Distribution of SGPT (ALT):
1. ALT is an enzyme found predominantly in the liver.
2.It is distributed in many tissues, with a moderate amount in:
1. Kidneys.
2. A small amount in:
3. Heart, skeletal muscles.
3.A minimal amount may be found in the pancreas, spleen, lungs, and RBCs
Age Male
U/L
Female
U/L
Newborn 12
months
13 to
45
13 to
45
one to 60
years
10 to
40
7 to 35
60 to 90 years 13 to
40
10 to
28
>90 years 6 to 38 5 to 24

14. SGOT (Aspartate aminotransferase, AST,
Glutamic oxaloacetic Transaminase)
1.Aspartate transaminase is also known as L-aspartate-2-oxoglutarate
aminotransferase, AST.
2.This enzyme catalyses the reversible transfer of amino groups
between an amino acid, and α-keto acids are called aminotransferase
or transaminases.
3.One of the aminotransferases is Aspartate aminotransferase (AST), or
the old name was glutamic -oxaloacetic transaminase (GOT).

15. Distribution of the SGOT (AST) in the body
This enzyme is distributed in all tissues (primarily all the tissues), but
the highest concentration is found in the liver, heart, and skeletal
muscles.
AST (SGOT) concentration is more in heart >liver> muscles>kidneys>pancreas.

16. The main feature of SGPT (ALT) and SGOT (AST):
Clinical parameters SGPT (ALT) SGOT (AST)
Normal range 5 to 35 IU/L 10 to 40 IU/L
Half-life in blood 35 to 57 hours (3 to 5 days) 12 to 22 hours
Distribution in the body 1.Main is the liver
2.Low concentration in other tissues
1.It is more in the heart than liver
2.It is present in skeletal muscles, brain, and kidneys
Location in the liver cells It is present in the cytoplasm only It is present in cytoplasm and mitochondria
Change with acute inflammatory conditions It is extremely sensitive It is moderately sensitive
The rise in metastatic or primary neoplasm It is moderate or no change It is markedly increased
In cirrhosis It is a mild to moderate increase It is moderately increase
In acute myocardial infarction It is a mild to moderate increase It is markedly increase

17. Alkaline Phosphatase Level (ALP)
1.The body contains many phosphatases. These are classified based on
pH at which they will show maximum activity.
2.ALP shows maximum activity between pH of 9 to 10.
3.Intestinal mucosa shows the greatest activity, followed by kidney,
bone, thyroid, and liver.
4.Regan isoenzymes are observed in 5% of cases with carcinoma. It is
identical to placental ALP isoenzyme.

18. Distribution of the alkaline phosphatase
1.This is an enzyme present in the blood, and its subtypes are present
in the liver, intestine, bones, and placenta.
2.ALP is found in many tissues, at or in the cell membrane.
3.ALP is a nonspecific enzyme capable of reacting with many different
substrates.
4.Liver and bone ALP are predominantly more in the serum.
Normal range : Alkaline phosphatase, serum: 74 - 390 U/L.

19. Gamma-glutamyl Transferase
1.γ-glutamyl-transferase is a membrane-bound enzyme that is mainly
present in the liver and cells lining the bile ductless and bile canaliculi.
2.γ-glutamyl-transferase was formerly called gamma-Glutamyl
transpeptidase, which is mainly present in hepatocytes.
3.Toa lesser extent is present in the kidneys, biliary tract epithelium,
intestine, pancreas, brain, heart, and spleen.
4.GGT activity is also seen in the capillary endothelium.
5.GGT is responsible for the extracellular metabolism of glutathione, and it is
the main antioxidant in the cells.
6.Serum GGT is raised in the new-born and comes to the adult level by 4
months of age.
7.GGT value may be higher in obese patients than in lean people.

20. γ-glutamyl-transferase (GGT) concentration at different sites
1.The main concentration is present in the hepatocytes.
2.GGT is found in the biliary tree’s epithelial cells, mostly in the interlobular
bile ducts and bile ductules. This is the reason that it is susceptible to
biliary injury.
I. GGT is present in the kidney, pancreas, spleen, heart, intestine, brain, and prostate
gland.
II. GGT level is higher in men because of the additional amount due to the prostate.
III.The kidney has a maximum amount, but the liver is considered the normal source of
serum activity.
IV.It is found throughout the hepatobiliary system and other tissues.
3.GGT is present in the microsomes of the cytoplasm and the cell membrane.
The normal range for adults is 5 to 55 U/L. Normal value ranges may vary
slightly among different laboratories.

21. Blood protein
Simple and conjugated proteins that comprise plasma proteins are often referred to as
blood proteins or serum proteins. Their average plasma concentration is not constant
and is influenced by the presence of protein, but usually, it is 7.4% and ranges between
6.5% and 8.4% in a healthy person. As a result, they can be utilized to diagnose and
predict diseases using their concentration as the criterion.
Blood proteins, also termed plasma proteins, are proteins present in blood plasma.
They serve many different functions, including transport of lipids, hormones, vitamins
and minerals in activity and functioning of the immune system.

22. Plasma proteins are classified into albumin, globulin (alpha 1 globulin, alpha 2
globulin, beta globulin), and other important plasma (Bence-jones protein,
fibrinogen).
Albumin helps move many small molecules through the blood, including
bilirubin, calcium, progesterone, and medicines. It plays an important role in
keeping the fluid in the blood from leaking into the tissues. Normal range – 3.4 to
5.4 g/dL (34 to 54 g/L).
Globulins are a family of globular proteins that have higher molecular weights
than albumins and are insoluble in pure water but dissolve in dilute salt
solutions. Some globulins are produced in the liver, while others are made by
the immune system. Globulins, albumins, and fibrinogen are the major blood
proteins. The normal concentration of globulins in human blood is about 2.6-3.5
g/dL.