1. LIVER FUNCTION TESTS

2. 2. Distinguish among the different types of liver diseases
1. Detect the presence of liver diseases
2. Distinguish among the different types of liver diseases
3. Gauge the extent of known liver damage
4. Follow response to treatment

3. Liver tests have shortcomings. They rarely
suggest a specific diagnosis rather they
suggest a general category of liver diseases,
such as hepatocellular or cholestatic; which
then further directs the evaluation..

4. AND EXCRETORY FUNCTIONS:
TESTS BASED ON DETOXIFICATIONS
AND EXCRETORY FUNCTIONS:
1. SERUM BILIRUBIN – a breakdown product of porphyrin ring of heme containing proteins
(conjugated,unconjugated)
unconjugated/indirect – insouble in water; bound to albumin in the blood
conjugated/direct – water soluble; excreted in kidneys

5. Normal serum bilirubin concentration: <17 micromol/L (1mg/dl)
Up to 30% of the total is direct-reacting

6. Elevation of unconjugated fraction of bilirubin: rarely due to liver disease
hemolytic disorder
genetic conditions: Crigler-Najjar, Gilbert Syndrome
Elevation of conjugated bilirubin: almost always implies liver or biliary tract disease

7. 2. URINE BILIRUBIN:
presence of bilirubinuria  liver diseases  almost 100% accurate
3. BLOOD AMMONIA: elevated in advanced liver diseases with significant muscle wasting  Hyperammonimea
There is a poor correlation between either the presence or the degree of acute enceph and elevation of blood ammonia
There is a poor correlation of the blood serum ammonia and hepatic function

8. 2 categories of serum enzymes:
Enzymes whose elevation in serum reflects damage to hepatocytes
Enzymes whose elevation in serum reflect cholestasis
Enzymes that do not fit precisely into either patterns

9. ENZYMES THAT REFLECT DAMAGE TO HEPATOCYTES
AMINOTRANSFERASES:
sensitive indicator of liver cell injury and most helpful in recognizing acute hepatocellular diseases such as hepatitis
These enzymes are normally present in the serum in low concentrations. They are released in the blood in greater amounts when there is damage to the liver cell membrane resulting in increased permeability

10. AST (Aspartate aminotransferase): liver, cardiac, skeletal, kidneys, brain, pancreas, lungs, leukocytes and erythrocytes
ALT (Alanine aminotransferase): found primarily in the liver

11. ENZYMES THAT REFLECT CHOLESTASIS
Alkaline phosphatase and 5’ nuleotidase: found near the bile canalicular membrane of hepatocytes
Gamma Glutamyl Transpeptidase: Endoplamic reticulum and in bile duct epithelial cells  lacks specificity

12. Alkaline phosphatase: liver, bone, placenta, less commonly small intestine
Elevation of liver-derived alkaline phosphatase is not totally specific for cholestasis and a less than 3 fold elevation can be seen in any type of liver disease

13. TESTS THAT MEASURE BIOSYNTHETIC FUNCTION OF THE LIVER
SERUM ALBUMIN: synthesized exclusively by hepatocytes
* has a slow turn over
not a good indicator of acute or mild hepatic dysfunction

14. SERUM GLOBULINS: group of proteins made up of gamma globulins (immunoglobulins) produced by B lymphocytes and alpha and beta globulins produced primarily in hepatocytes
Increases in the IgM levels are common in primary biliary cirrhosis
Increases in the IgA levels occur in alcoholic liver diseases

15. COAGULATION FACTORS:
With the exception of Factor VIII, the blood clotting factors are made exclusively in hepatocytes.
Because of their rapid turnover, measurement of the clotting factors is the single best acute measure of hepatic synthetic function and helpful in both the diagnosis and assessing the prognosis of acute parenchymal liver disease

16. Serum prothrombin time: collectively measures factors II, V, VII, and X
Marked prolongation of prothrombin time, >5s above control is a poor prognostic sign in acute in acute viral hepatitis and other acute and chronic liver diseases.

17. THANK YOU!