Stomach and Intestines: Lab Evaluation

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Stomach and Intestines: Lab Evaluation by Mind Map: Stomach and Intestines: Lab Evaluation

1. Diseases

1.1. H. Pylori

1.1.1. Biopsy Positive Culture? pH change

1.1.2. Breath test Breath in 13C-labeled urea Monitor breath for 13C-labeled CO2 Sensitivity 94% Specificity 95 %

1.1.3. IgG

1.2. Zollinger-Ellison Syndrome

1.3. Gastritis, Pernicious anemia

1.3.1. Gastritis Acute Transient Caused by Chronic H. Pylori Autoimmune Chronic Gastritis Chemical Gastropathy Inflammatory processes leading to Labs Achlorhydria / hypochlorhydria

1.4. Malabsorption

1.4.1. Characterized by amylorrhea excess starch Steatorrhea Excess fat Creatorrhea Meat fibers, protein

1.4.2. May be due to Pancreatic dieases Chronic pancreatitis Carcinoma Cystic Fibrosis Trauama ZES Liver disease with blockage of bile flow Intestinal diseases Celiac disease Crohn's disease Whipple's disease Lymphoma Intestinal resection Blind loop syndrome Carcinoid Syndrome

1.4.3. Treatment Resin Bile-acid sequestering agents

1.4.4. Fat Malabsorption Fecal fat excretion Quantiative Qualitative Fat malabsoprtion Fecal Fat determination 14C-triolein breath test Serum Beta-Carotene levels Beta-carotene is fat soluble precursor to vitamin A Adequately present in most diets Decreased serum levels suggest fat malabsoprtion Can't make Vitamin A if you can't absorb Ffat Other Labs affected by Malabsorption Serum calcium Serum ALP Serum Proteins Serum Urea nitrogen Hypocholesterolemia Prothrombin Time Glucose Vitamin A

1.5. Colorectal cancer

1.5.1. Screening FOBT Guaiac Test Presence of Heme in feces catalyzes oxidation of guaiac Three consecutive stools should be sampled False Negatives False Positives

1.5.2. Confirmatory Test Blood - Tumor Markers CEA - Carcinoembryonic antigen CEA CA19-9 Colonoscopy - Tumor Tissue MSI - Microsatellite instability Oncogene BRAF mutation Tumor suppressor gene mutations Tumor M2-PK

1.6. Diarrhea

1.6.1. Acute Diarrhea Evaluation of Acute Diarrhea Schema 2 Schema 1

1.6.2. Chronic Diarrhea Evaluation of Chronic Diarrhea Rule out Fecal Calprotectin and Lactoferrin Endoscopy with mucosal biopsy

1.6.3. Pathophysiologic Mechanisms 1. Decreased absorption of fluid and electrolytes 2. Increased secretion of fluids and electrolytes

1.6.4. Frequent Passage of Loose watery stool Exudative Diarrhea Blood and pus present in stool Inflammatory bowel diseases Severe infections

2. Lab Tests

2.1. Fecal occult blood

2.2. Gastrin and Secretin

2.2.1. Serum Gastrin levels are used to diagnose Zollinger-Ellison Syndrome Pathophysiology Testing Algorithm Autoimmune Gastritis Pathophysiology of Hypergastrinemia Markedly increased gastric acid secretion Increased gastric acid output leads to Increased acid in intestine leads to

2.2.2. Secretin Stimulation Test Measures ability of the pancreas to respond to secretin Normal Secretin ↓ Gastrin Confirmatory Test Gastrinoma / ZES May be abnormal in Pancreatic diseases Secretin Secreted by Stimulated by Stimulates

2.3. Gastric Acid Testing

2.3.1. Measurements Initial Resting / Basal measurement amt. HCl produced by stomach under basal / fasting conditions, without exposure to visual, auditory, olfactory stimuli (cephalic digestion I guess) Maximal stimulation follows basal measurement

2.3.2. Demographics Young > Old M > F

2.3.3. Decreased in gastric carcinoma gastric ulcer females aging persons

2.3.4. Hyperacidity (Increased) in dudodenal ulcer jejunal ulcer

2.3.5. Achlorhydria pernicious anemia advanced carcinoma of the stomach Other anemias hypochromic anemia aplastic anemia hypothyroidism nutritional megaloblastic anemia

2.4. Schilling Test

2.4.1. B12 Deficiency Test

2.4.2. Absorption of B12 is measured Orally administered radio-labeled B12 quantitated by its appearance in the urine >8% excretion < 7% excretion

2.4.3. B12 essential cofactor DNA synthesis Absorption intrinsic factor Ileum Deficiency Decreased IF Decreased absorption