Liver function tests (LFTs) measure liver enzymes, plasma proteins, and bilirubin to evaluate liver health and detect liver injury or disease. Elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) indicate liver cell damage. ALT is more specific to the liver while AST can also be elevated in other conditions. Albumin levels decrease in advanced liver disease. The AST/ALT ratio helps distinguish between viral hepatitis or toxic injury (ratio <1) versus alcoholic liver disease or cirrhosis (ratio >1). LFTs along with history, exam, ultrasound and CT can help diagnose specific liver disorders.

1. Liver function tests section 5 & 6
(Part 1)

2. Review: Liver
• The liver is the largest organ in the body,
weight 1200-1500 g.
• The working cells of the liver are known as
hepatocytes, which have a unique capacity to
reproduce in response to liver injury.
• Although the liver's ability to react to damage
and repair itself is remarkable, repetitive
insults can produce liver failure and death.
• Liver cells carry out a wide variety of
metabolic functions facilitated by the rich
blood supply derived from the gut as well as
systemic circulation.

3. Liver is a multifunctional organ that is involved
in diverse body functions.

4. What is Purpose of LFTs?
• LFTs alone do not give the physician full information, but used in combination
with a careful history, physical examination (particularly ultrasound and CT
Scanning), can contribute to making an accurate diagnosis of the specific liver
disorder.
• Different tests will show abnormalities in response to
oliver inflammation,
oliver injury due to drugs, alcohol, toxins, viruses
oLiver malfunction due to blockage of the flow of bile
oLiver cancers

5. Hepatic
function tests
Enzymes Plasma
proteins
Bilirubin
• ALT
• AST
• ALP
• GGT
• LDH
• Total protein
• Albumin
• Prothrombin

6. Plasma & Serum

8. Liver enzymes: Aminotransferases
1. Alanine amino transferase (ALT) /Serum Glutamate Pyruvate Transaminase
(SGPT ).
2. Aspartate aminotransferase (AST)/ Serum Glutamate Oxaloacetate
Transaminase (SGOT).
oThey are found normally in blood circulation as a result of turn over of hepatocytes,
but their elevation indicates liver cell damage.
oThey catalyze transamination reaction “Transfer amino group from one amino acid
to another ketoacid”.

9. Alanine amino transferase (ALT) /Serum Glutamate Pyruvate Transaminase
(SGPT).
• ALT transfers an amino group from alanine to α-ketoglutarate. It is present in moderately high
concentration liver, but is low in cardiac and skeletal muscles and other tissues located in the
cytosol of the cell.
• ALT is the most sensitive marker for liver cell damage; since it is only synthesized by liver cells
other enzymes may be also synthesized by other organs.
• If there is a slight liver cell damage, GPT firstly leak into the bloodstream, so that the serum
GPT increased
• Normal values: Up to 45 U/ml.
oInterpretation:
• The increased activity showed in conditions in which hepatocytes are damaged or die such as:-
• Viral hepatitis -Alcoholic hepatitis
• Drug toxicity -Drug induced hepatitis
• Shock

10. Aspartate aminotransferase (AST)/ Serum Glutamate Oxaloacetate Transaminase
(SGOT).
• This enzyme transfers an amino group from aspartate to α-ketoglutarate.
• AST is found in practically every tissue of the body, including red blood cells. It is in particularly has
high concentration in cardiac muscle and liver, intermediate in skeletal muscle and kidney, and in much
lower concentrations in the other tissues. AST located in both mitochondria and cytosol of the cell.
• AST is less specific for liver disease, ALT & AST levels in plasma/serum are sensitive index of
hepatocellular damage.
• The GOT mainly in the "mitochondria“ of liver cells. if there is a slight liver cell damage, GOT don`t
leak into the bloodstream. When the GOT was significantly higher, mitochondria of liver cells are
injured.

11. • Normal values: Up to 40 U/ml
oInterpretation: The serum activity of AST is increased in:
– Alcoholic hepatitis - Myocardial infarction
– Renal infarction - Hemolytic condition
– Trauma (A trauma patient is someone who has suffered serious and life-threatening
physical injury potentially resulting in secondary complications such as shock,
respiratory failure and death)

12. Experiment: Measuring serum ALT level

13. (Fig.1): Standard curve of ALT

14. Experiment: Measuring serum AST level

15. (Fig. 2): Standard curve of AST

16. Albumin; protein related to liver function.
• Albumin is the major protein synthesized in liver, thus can be use to assess hepatic
function. (Long half life 18 – 20 days)
• Albumin is essential for maintaining the:
─ Osmotic pressure
─ It is also transport protein for many endogenous and exogenous substances such as;
thyroid hormones, other hormones particularly fat soluble ones, fatty acids to the
liver, unconjugated bilirubin, and drugs.

17. • Normal value:
– Children: 3.8-4.2 g/dl
– Adults: 3.5- 5.5 g/dl
oInterpretation:
Hypoalbuminemia
– Albumin level decreases in end stage liver disease; Liver cirrhosis ( is a late stage of scarring
(fibrosis) of the liver caused by many forms of disease or conditions, such as hepatitis and chronic
alcoholism)
(Chronic liver disease like cirrhosis, reflects liver damage and decreased albumin synthesis).
– Inflammation.
– Malignant hepatocellular damage.
– Non hepatic cause of low albumin;
– ( Protein malnutrition, Nephrotic syndrome)

18. Experiment: Measuring serum albumin level

19. AST/ALT Ratio
• When ALT & AST are abnormally elevated, AST/ALT ratio can be
calculated.
• Viral hepatitis, and acute hepatotoxicity typically show elevations in
ALT that are greater than AST elevations (AST/ALT<1.0).
• ALT is elevated to a lesser degree than AST in alcoholic liver
disease and cirrhosis, bile duct obstruction, or metastatic tumor to
the liver (AST/ALT >1.0).

20. AST/ALT Ratio
AST/ALT < 1.0
ALT >>AST
AST/ALT > 1.0
AST >>ALT
AST/ALT > 2
AST >>>ALT
• Acute viral
hepatitis (high
levels 10-40
fold increase).
• Acute
hepatotoxicity
• AST & ALT
increase 4 or 5
times in liver
cirrhosis (with
low albumin
level)
• Alcoholic
hepatitis
• Metastatic tumor
to the liver