The document discusses liver function tests presented by Dr. Shruti Gera, detailing the liver's metabolic, synthetic, excretory, detoxification, regulatory, and storage functions. It outlines the various tests used to evaluate liver function, indications for testing, and the interpretation of results, specifically regarding bilirubin metabolism, ammonia detoxification, protein synthesis, and enzyme levels. The document emphasizes the significance of these tests in diagnosing and monitoring liver diseases, including their specific clinical implications.

1. LIVER
FUNCTION
TESTS
PRESENTED BY
DR. SHRUTI GERA
JR PATHOLOGY

3. FUNCTIONS OF
LIVER

4. 1) METABOLIC FUNCTION
Carbohydrate metabolism : glycolysis, glycogen synthesis, breakdown,
gluconeogenesis and HMP shunt
 Lipid metabolism : fatty acid synthesis, ketogenesis, cholesterol synthesis and
excretion, bile acid synthesis, 25- hydroxylation of vitamin D and lipoprotein
synthesis.

5. Protein metabolism : urea synthesis from ammonia, synthesis of plasma
proteins(except immunoglobulins) and some coagulation factor synthesis.
Hormone metabolism : metabolism and excretion of steroid hormones and
metabolism of peptide hormone.

6. 2) Synthesis function : synthesis of plasma proteins, clotting factors, cholesterol,
TAG and lipoproteins.
3) Excretory function : excretion of bile pigments and bile salts into the bile.
4) Detoxification : ammonia is detoxified to urea ; drugs and other xenobiotics are
detoxified and excreted.
5) Regulation of blood glucose levels : by hepatic glycogenolysis and
gluconeogenesis.
6) Storage function : glycogen, vitamins A, D, K, B12 and iron.

9. LIVER FUNCTION
TESTS

10. • Laboratory tests for evaluation of liver disease are based on evaluation of
these normal functions of liver.
• Function tests are the tests carried out to assess whether a particular organ
is functioning normally or not.
• Liver function tests are a group of tests that help in diagnosis, assessing
prognosis and monitoring therapy.

11. INDICATIONS OF LIVER FUNCTION TESTS
Jaundice
Suspected liver metastasis
Alcoholic liver disease
Any undiagnosed chronic illness
Annual check up of diabetic patient
Coagulation disorders
Therapy with statins to check hepatotoxicity

12. • Liver function tests can be classified into five classes according to the function of
the liver.
1) Tests based of excretory function :
1) serum bilirubin
2) Urine bilirubin
3) Urine bile salts
4) BSP dye tests
1) Tests based on detoxification function :
1) Blood ammonia and bilirubin
2) Hippuric acid test

13. 3) Tests based on synthetic function:
 Plasma proteins, albumin and globulins
 Prothrombin time
4) Tests based on metabolic function:
 Galactose tolerance test
 Determination of serum cholesterol and ratio of free to
esterified cholesterol
 Serum protein estimation
 Serum ammonia estimation

14. 5) Determination of serum enzymes:
 Serum alanine transaminase (ALT)
 Serum aspartate transaminase (AST)
 Serum alkaline phosphatase (ALP)

15. SPECIAL TESTS (TESTS FOR METABOLIC LIVER
DISEASE)
 Ceruloplasmin
Ferritin and iron
Alpha-1 antitrypsin
Beta-2 microglobulin
Alpha fetoprotein (AFP)

16. LIVER FUNCTION TEST BASED ON
EXCRETORY FUNCTION

17. TESTS BASED ON BILIRUBIN
METABOLISM
 Bilirubin is the excretory end product of heme.
 It is conjugated to form bilirubin diglucuronide (aka direct bilirubin).
 Bilirubin (unconjugated/indirect) is insoluble in water but bilirubin diglucuronide is
soluble in water.

19. Normal concentration of bilirubin:
• Total serum bilirubin - 0.2 to 1 mg/dl
• Direct serum bilirubin - 0.1 to 0.4 mg/dl
• Indirect serum bilirubin - 0.2 to 0.7 mg/dl
Seum bilirubin estimation by Van Den Bergh reaction.

20. CLINICAL INTERPRETATION
Increase in serum bilirubin occurs due to many causes and results in jaundice.
Bilirubin metabolism is deranged in three important diseases:
• Hemolytic jaundice (pre-hepatic)
• Hepatitis (hepatic)
• Obstructive jaundice (post- hepatic)

22. TESTS BASED ON DETOXIFICATION
FUNCTION
DETERMINATION OF BLOOD AMMONIA
• Liver detoxicates ammonia to form urea.
• In liver disease, ability to remove ammonia may be impaired.
• Normal levels of blood ammonia – 40-70 mg/dl
Clinical interpretation :
• High blood levels of ammonia are found in acute hepatitis and cirrhosis.

23. TESTS BASED ON SYNTHETIC FUNCTION
DETERMINATION OF SERUM ALBUMIN AND GLOBULIN
NORMAL CONCENTRATIONS OF SERUM PROTEINS
 Total serum protein - 6 to 8 gm/dl
 Serum albumin - 3.5 to 5.5 gm/dl
 Serum globulin - 2 to 3.5 gm/dl
 Albumin/ globulin ratio - 1.2 :1 to 1.6 : 1

24. CLINICAL INTERPRETATION
• Hypoalbuminemia may occur in hepatocellular disease e.g. cirrhosis
• Hyperglobulinemia may occur in cirrhosis and infectious hepatitis.
• In advanced stages of liver disease, albumin is decreased and globulins are
increased, so that the A/G ratio may be reversed.

25. DETERMINATION OF PROTHROMBIN TIME
• Various proteins that participate in blood coagulation are synthesised in
liver e.g. fibrinogen, factor II, V, VII, IX & X.
• If any of these factors is deficient, the deficiency causes prolonged
prothrombin time e.g. vit K deficiency.

26. TESTS RELATED TO ENZYMES
• Liver cells contain several enzymes.
• In liver damage, these enzymes are released into blood which leads to
increase in their levels in blood.

27. MOST COMMONLY AND ROUTINELY USED ENZYMES:
• SERUM ASPARTATE TRANSAMINASE (AST)
• SERUM SERUM ALANINE TRANSAMINASE (ALT)
• SERUM ALKALINE PHOSPHATASE (ALP)
OTHER ENZYMES (not used routinely) :
• Serum nucleotidase
• Lactate dehydrogenase
• Isocitrate dehydrogenase
• γ- glutamyl transferase

29. SERUM TRANSAMINASES
• AST OR SGOT - 4-17 IU/L
• ALT OR SGPT - 3-15 IU/L
Although, both AST and ALT are commonly thought of as liver enzymes because of
their high concentrations in liver , only ALT is markedly specific for liver.
AST is widely present in myocardium, skeletal muscle, brain and kidney and may
rise in acute necrosis of these organs besides liver cell injury.

30. AST > ALT is seen in alcoholic liver disease (ratio of AST/ ALT > 2 is quite
suggestive).
Moderate elevation of amino transferases (100-300 U/L) is seen in alcoholic
hepatitis, autoimmune hepatitis, wilson’s disease and non alcoholic chronic
hepatitis.
Minor elevations (<100 U/L) is seen in chronic viral hepatitis(hep C), fatty liver and
non alcoholic steatohepatitis (NASH).

31. CLINICAL SIGNIFICANCE OF AST/ ALT RATIO:
Normal AST:ALT is 0.8
Ratio > 2 is seen in-
• Alcoholic hepatitis
• Hepatitis with cirrhosis
• NASH
• Liver metastasis
• Myocardial infarction
• Erythromycin treatment

32. CLINICAL INTERPRETATION:
• ALT estimations are useful in early diagnosis to evaluate severity and prognosis of
liver disease.
• In hepatitis, the levels of both these enzymes are increased (500-1500 IU/L).
• In obstructive jaundice, also increase occurs but doesnot exceed 200-300 IU/L.
• In hemolytic jaundice, levels of these enzymes are normal.

33. ALKALINE PHOSPHATASE (ALP)
• ALP is produced by many tissues, especially bone, liver, intestine and placenta and
is excreted in the bile.
• In absence of bone disease and pregnancy, the levels are generally increased due
to hepatobiliary disease.
• Normal levels in plasma 3-13 KA units/100ml.
• ALP is normally excreted through bile, so raised levels are seen in obstructive
jaundice.

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