INTERPRETATION OF LABORATORY & DIAGNOSTIC TESTS GI SYSTEM Nora A.Kalagi, MSc. 326 PHCL April 2016

Objectives 1.Identify the clinical application of laboratory & diagnostic tests specific to the GI, and endocrine systems. 2.Solve patient cases that involve assessing common laboratory & diagnostic test results pertaining to the GI,, and endocrine systems

GASTROINTESTINAL (GI) SYSTEM

Liver: Defining Terms  Hepatitis: refers to any swelling, inflammation, or irritation of the liver  Inflammation that lasts long enough will create fibrosis  Extreme fibrosis is called cirrhosis

Liver We can assess liver function and disease state by measure: Biliary system (Liver enzymes and bilirubin) Liver synthetic ability

Laboratory Tests ◦ 1)Biliary System ◦ Product of hemoglobin breakdown  Total Bilirubin ◦ Sum of direct + indirect + delta bilirubin ◦ Useful in diagnosis & monitoring of liver disease & hemolytic anemia & in the assessment of the severity of jaundice ◦ Total bilirubin ( mg/dl) ◦ A patient is generally visibly jaundiced if the bilirubin level is greater than 2 mg/dl

Laboratory Tests (Biliary System)  Direct Bilirubin ◦ Water-soluble conjugated post hepatic bilirubin ◦ Increased in biliary disease (e.g. extrahepatic bile duct obstruction, impaired bile transport) ◦ Increased in some liver diseases (e.g. hepatitis, cirrhosis)  Indirect Bilirubin ◦ Unconjugated bilirubin ◦ Increased in hemolytic anemia (rapid severe hemolysis) & some liver diseases

Laboratory Tests (Biliary System)  Delta Bilirubin ◦ Albumin-bound conjugated bilirubin ◦ Calculated value (= total bilirubin-(unconjugated + conjugated)) ◦ Increasd in biliary obstruction & some liver diseases  Alkaline Phosphatase (ALP) ◦ Not a specific test for liver dysfunction ◦ Present in liver, intestine and bone ◦ Elevated in biliary cirrhosis, cirrhosis,intrahepatic bile duct disease

Laboratory Tests ◦ 2) Hepatic Synthetic Function ◦ One way of assessing liver's ability to metabolize drugs is to assess it’s synthetic function by evaluating the quantity of specific products produced by the liver A.Ammonia ◦ The liver synthesizes urea from ammonia ◦ Serum ammonia is increased if the liver is damaged or if blood flow is compromised ◦ Not used as a routine screening test, but used to confirm a diagnosis of hepatic encephalopathy

Laboratory Tests (Hepatic Synthetic Function) B.Protein Production  Albumin ◦ Circulating albumin takes several weeks to clear from the body ◦ A rapidly declining level indicates greatly impaired hepatic function ◦ Long-standing liver disease is associated with very low concentrations

Laboratory Tests (Hepatic Synthetic Function) B.Protein Production  Vitamin K-dependent clotting factors (factors II, VII, IX,X) ◦ Lack of production of these factors prolongs the prothrombin time (PT) & activated partial thromboplastin time (aPTT) ◦ The PT is prolonged earlier than the aPTT & often is used as an early indicator of impaired hepatic synthetic function ◦ Both the PT & aPTT are prolonged in long-standing severe hepatic dysfunction

Laboratory Tests ◦ 3) Hepatocellular Enzymes Hepatocytes contain numerous enzymes that leak into the serum when liver cells die or are damaged Elevations occur in the presence of marked changes in hepatic circulation (e.g. cardiovascular shock) & diseases associated with hepatocellular damage (hepatitis, cirrhosis, inflammatory diseases) Serum enzymes may not be markedly elevated in severe, chronic, end-stage liver disease (liver is burned out)

Laboratory Tests (Hepatocellular Enzymes) Very high elevations (>20 X normal) are associated with viral or toxic hepatitis Moderately high elevations (3 to 10 X normal) are associated with infectious chronic active hepatitis, extrahepatic bile duct obstruction, & intrahepatic cholestasis Modest elevations (1-3 X normal) are associated with pancreatitis, alcoholic fatty liver, biliary cirrhosis, & neoplastic infiltration

Laboratory Tests (Hepatocellular Enzymes) ◦ Alanine Aminotransferase (ALT) ◦ ALT is found in high concentrations in hepatocytes & is considered a specific marker of hepatocellular damage ◦ Aspartate Aminotransferase (AST) ◦ AST is found in hepatocytes, myocardial muscles, skeletal muscle, the brain, & the kidneys ◦ It is used as a nonspecific marker of hepatocellular damage

Laboratory Tests (Hepatocellular Enzymes) ◦ Gamma Glutamyl Transpeptidase (GGT) ◦ GGT is found in hepatobiliary, pancreatic, & kidney cells ◦ It is elevated in most hepatocellular & hepatobiliary diseases ◦ Elevations correlate better with obstructive disease ◦ An early indicator of alcoholic liver disease ◦ Lactate Dehydrogenase (LDH) ◦ LDH is found in the heart, brain, erythrocytes, kidneys, liver, skeletal muscle, & ileum (LDH5 specific to liver) ◦ Elevations occur during shock syndrome & diseases associated with hepatocellular damage (hepatitis, cirrhosis)

Laboratory Tests ◦ 4) Pancreatic Tests Amylase ◦ Secreted by pancreas, bowel ◦ Not specific but easier to measure than lipase ◦ A screening & monitoring parameter for acute pancreatitis Lipase ◦ Specific marker for acute pancreatic disease ◦ Parallels increase in serum amylase ◦ In chronic pancreatitis the pancreas may be "burned out" & unable to secrete lipase

Laboratory Tests ◦ 5) Stool ◦ Evaluated for color; consistency; & the presence of obvious or occult blood, fat, ova & parasites, microorganisms, & white blood cells (WBCs)  Color of stool provides important diagnostic & monitoring information ◦ Black: upper gastrointestinal tract bleeding or iron therapy ◦ Gray stools: Steatorrhea ◦ Light gray stools: bile duct obstruction

Laboratory Tests (Stool) – Watery stools: rapid GI transit & malabsorption syndromes – Hard stools: dehydration – Obvious blood: colonic bleeding – Occult blood: upper or lower GI tract bleeding, may be identified for several weeks after GI bleeding – Stool fat is increased in diseases associated with altered bacterial flora, increased GI motility, decreased enzyme & bile acid content – WBCs are associated with a variety of infectious processes & IBD

Diagnostic Tests & Procedures ◦ Ascitic Fluid Analysis ◦ Abdominal paracentesis is used to obtain ascitic fluid for analysis. It is then assessed for: ◦ Color ◦ Cell count ◦ Protein ◦ Others content

Diagnostic Tests & Procedures ◦ Abdominal Radoigraphy ◦ The abdominal radiograph includes the kidneys, ureter & bladder ◦ Used to identify intestinal obstruction & other organ-specific structural abnormalities

Diagnostic Tests & Procedures ◦ Barium Studies Oral barium solution: The patient swallows contrast material, such as barium sulfate, & x-ray films are taken to visualize the esophagus, stomach, & small intestine Barium enemas are used to visualize the large intestine Double-contrast barium enema: technique uses barium & air to visualize the large intestine & is considered a more precise procedure

GI Diagnostic Test & Procedure Single contrast barium enema study showing an 'apple core' narrowing in the sigmoid colon Double contrast barium enema - normal study

Diagnostic Tests & Procedures ◦ Capsule Endoscopy ◦ Patient swallows a disposable capsule about the size of a large vitamin tablet that contains a miniature video camera, a light source, a miniature transmitter, & a battery ◦ Images are transmitted to an external receiver in a belt worn around the patient's waist ◦ Peristalsis moves the capsule through the GI & it is excreted rectally

Diagnostic Tests & Procedures ◦ Cholescystography ◦ Used to evaluate gallbladder function & anatomy ◦ Orally administered iopanoic acid concentrates in the gallbladder, opacifying it for visualization ◦ Sigmoidscopy ◦ An endoscope is used to evaluate GIT from anus to about 60 cm into the terminal colon ◦ Used to screen for rectosigmoid cancer and obtain biopsies

Diagnostic Tests & Procedures ◦ Schilling test Used to detect malabsorption of vitamin B12 D-Xylose test Is used to screen for carbohydrate malabsorption.