(PART 3) Gastrointestinal System

Bilirubin

BILIARY SYSTEM
- Is useful in the diagnosis and monitoring of liver disease and hemolytic anemia and in the assessment of the severity of jaundice.
- A patient is generally visibly jaundiced if the this level is higher than 2 mg/dL.

Alkaline Phosphatase Level

BILIARY SYSTEM
Is elevated in biliary cirrhosis, cirrhosis, and intrahepatic bile duct disease

Direct bilirubin

BILIARY SYSTEM
- Is water-soluble conjugated posthepatic bilirubin.
- It is increased in biliary disease (e.g., extrahepatic bile duct obstruction, physical impairment of bile flow, impaired bile transport) and some liver disease (e.g., hepatitis, cirrhosis, hepatic neoplasm).

Delta bilirubin

BILIARY SYSTEM
- Is albumin-bound conjugated bilirubin.
- Its level is a calculated value ([delta bilirubin = total bilirubin – (unconjugated bilirubin + conjugated bilirubin)].
- Is metabolically inactive and is cleared slowly from the body.
- Its level is increased in biliary obstruction and some liver disease.

Indirect bilirubin

BILIARY SYSTEM
- Is unconjugated bilirubin.
- Its level is increased in hemolytic anemia (rapid, severe hemolysis) and some liver disease.

Total bilirubin

BILIARY SYSTEM
- Is the sum of all three forms of bilirubin (direct bilirubin, indirect bilirubin, and delta bilirubin).
- Is increased in hepatic and hemolytic diseases.

Ammonia

HEAPTIC SYNTHETIC FUNCTION
- The liver synthesizes urea from this.
- Is increased if the liver is damaged or if blood flow is compromised.
- Although its serum level is not used as a routine screening test, it is sometimes performed to confirm a diagnosis of hepatic encephalopathy.

Albumin

HEAPTIC SYNTHETIC FUNCTION
- Takes several weeks to clear from the body, a rapidly declining serum protein level indicates greatly impaired hepatic synthetic function.
- Longstanding liver disease is associated with very low serum protein concentrations.

Vitamin K–dependent clotting factors (factors II, VII, IX, and X)

HEAPTIC SYNTHETIC FUNCTION
- Lack of production of this may prolong the prothrombin time (PT) and activated partial thromboplastin time (aPTT).
- The PT is prolonged earlier than the aPTT and often is used as an early indicator of impaired hepatic synthetic function.
- Both the PT and aPTT are prolonged in longstanding severe hepatic dysfunction.

Hepatocellular Enzymes

- Elevations of these enzymes occur in the presence of marked changes in hepatic circulation (e.g., cardiovascular shock) and diseases associated with hepatocellular damage (hepatitis, cirrhosis, inflammatory disease, and infiltrative hepatic diseases).
- However, serum enzyme levels may not be markedly elevated in severe, chronic, end-stage liver disease (because the liver is burned out).

Very high elevations

Hepatocellular Enzymes
(more than 20 times the normal level) are associated with viral or toxic hepatitis.

Moderately High Elevations

Hepatocellular Enzymes
(3 to 10 times normal) are associated with infectious mononucleosis, chronic active hepatitis, extrahepatic bile duct obstruction, and intrahepatic cholestasis.

Modest elevations

Hepatocellular Enzymes
(one to three times normal) are associated with pancreatitis, alcoholic fatty liver, biliary cirrhosis, and neoplastic infiltration.

Alanine aminotransferase (ALT)

HEPATOCELLULAR ENZYMES
Is found in high concentrations in hepatocytes and is considered a specific marker of hepatocellular damage.

Aspartate aminotransferase (AST)

HEPATOCELLULAR ENZYMES
- Is found in hepatocytes, myocardial muscles, skeletal muscle, the brain, and the kidneys.
- It is used as a nonspecific marker of hepatocellular damage.

Gamma glutamyl transpeptidase (GGT)

HEPATOCELLULAR ENZYMES
- Is found in hepatobiliary, pancreatic, and kidney cells.
- It is elevated in most hepatocellular and hepatobiliary disease, although elevations correlate better with obstructive disease than with pure hepatocellular damage.
- An elevated level is an early indicator of alcoholic liver disease.

Lactate dehydrogenase (LDH)

HEPATOCELLULAR ENZYMES
- Is found in the heart, brain, erythrocytes, kidneys, liver, skeletal muscle, and ileum.
- Elevations occur during shock syndrome (marked changes in circulation) and in diseases associated with hepatocellular damage (hepatitis, cirrhosis, inflammatory disease, and infiltrative disease).

Stool

- Is evaluated for color, consistency, and the presence of obvious or occult blood, fat, ova and parasites, microorganisms, and white blood cells (WBCs).
- The color provides important diagnostic and monitoring information.

Black Stools

STOOLS
May indicate upper gastrointestinal tract bleeding; however, iron therapy may produce a similar color.

Gray Stools

STOOLS
Are generally associated with steatorrhea; light gray stools may indicate bile duct obstruction.

Watery Stools

STOOLS
Are indicative of rapid gastrointestinal tract transit and malabsorption syndromes.

Hard Stools

STOOLS
May indicate dehydration.

Occult Blood

STOOLS
Present in both upper and lower gastrointestinal tract bleeding, may be detected for several weeks after gastrointestinal tract bleeding.

Stool Fat

STOOLS
Is increased in diseases associated with altered bacterial flora, increased gastrointestinal tract motility, decreased enzyme and bile acid content, and loss of absorptive surfaces.

Alpha fetoprotein

MISCELLANEOUS
- Is the major protein produced by the fetus in the first 10 weeks of life.
- It also is produced by rapidly multiplying hepatocytes and is used as a marker of hepatocellular carcinoma.

Carcinoembryonic antigen (CEA)

MISCELLANEOUS
- Is a tumor marker found in the blood.
- It is associated with rapid multiplication of digestive system epithelial cells and is used to monitor tumor recurrence