Gastrointestinal Disease PDF

Gastrointestinal Disease Date: 10/16/2024 Learning objectives:  Identify the primary and  Compare and contrast acute secondary organs of the versus chronic diarrhea as to gastrointestinal system possible disease corre...

Gastrointestinal Disease Date: 10/16/2024 Learning objectives:  Identify the primary and  Compare and contrast acute secondary organs of the versus chronic diarrhea as to gastrointestinal system possible disease correlations  Explain the physiology of the  Discuss the tests used to gastrointestinal system, including diagnose the etiologies of acute carbohydrate digestion, protein or chronic diarrhea digestion, and lipid digestion  Discuss the two main divisions of  Compare the various tests for inflammatory bowel disease and identifying Helicobacter pylori how they differ with regard to infection and how H. pylori disease presentation infection is associated with  Discuss the tests to diagnose gastric and duodenal ulcers diverticulitis and diverticulosis  Explain how the calcium infusion  Compare and contrast other GI test, the octreotide test, and the disease mechanism, laboratory secretin test are used in the tests for diagnosis, and diagnosis of Zollinger-Ellison treatment syndrome Gastrointestinal (GI) system  Turning food into energy  Ingestion, mechanical breakdown, and chemical breakdown  Secretion, absorption, and excretion  Primary organs  mouth, esophagus, stomach, small intestine, and large intestine  Accessory organs  liver, gallbladder, and pancreas Anatomic Review  The GI tract is divided into upper and lower portions:  The upper GI tract includes: the mouth, esophagus, stomach, and part of the small intestine.  The lower GI tract includes: the remaining portion of the small intestine, the large intestine, the rectum, and the anus.  Accessory organs:  The pancreas, liver, and gallbladder are not technically part of the GI tract although they play important roles in digestion and in the absorption of nutrients. Anatomic Review  Mouth  Ingestion and the beginnings of digestion occur here  Salivary glands:  Parotid  Sublingual  Submandibular  Majority of saliva are produced from the submandibular  Saliva:  99.4% water  Amylase and lysozyme  Tongue, teeth, hard palate, and soft palate Jeewanjot S. et. al., 2021  Anatomic Review  Esophagus:  Swallowing food includes:  Tongue, pharyngeal muscles, soft palate, and epiglottis Tracheducation, 2019  The esophagus is posterior to the trachea  Approximately 28 cm long and 2 cm wide  Pass food to stomach through peristalsis movement  No absorption  Major layers:  Mucosa and submucosa,  Muscular and adventitia Ciara Durcan. et. al., 2021 Anatomic Review  Stomach:  The stomach, a hollow organ at the end of the esophagus, receives food from the esophagus.  The stomach is divided into four regions:  Fundus, cardia, body, and pylorus.  The stomach has four layers:  Mucosa, submucosa, muscular, and serosa layers Anatomic Review  Stomach:  There are four different types of cells that line the stomach and secrete various substances  Three exocrine types of cells glands:  Mucosal cells secrete mucus  Parietal cells secrete HCl  Chief cells secrete pepsinogen (pepsin)and chymosin (new borne)  One endocrine cells secrete gastrin:  Gastrin is a hormone that stimulates secretion of gastric acid by the parietal cells of the stomach and aids in gastric motility. Anatomic Review  Small intestine:  The small intestine is approximately 22 ft long and is composed of three main sections:  duodenum, jejunum, and ileum.  Play key role in digestion and absorption Linica Udayet.al., 2017  The small intestine has four layers:  Mucosa, submucosa, muscular, and serosa layers  The mucosa layer has a what is called intestinal villi  Microvilli to increase the surface area  Has additional digestive enzymes needed to further break down oligosaccharides to monosaccharides  Lacteal lymphatic vessel which absorb lipids Anatomic Review  Large intestine:  Cecum is the beginning of the large intestine  Appendix: vestigial structure (appendectomy)  Primary function  The reabsorption of nutrient (less than stomach and small intestine), water and formation of solid feces  Divided into multiple segments:  Ascending colon, Transverse colon, Descending colon, and Sigmoid colon  The large intestine is followed by:  Rectum: storage of feces  Anus: has internal and external anal sphincters Anatomic Review  Accessory organs:  Liver  Gallbladder  Pancreas  All connected to GI tract via ducts that transfer substances to small intestine GI Normal Physiology  Carbohydrate digestion:  Salivary amylase  Starch and glycogen to disaccharides  Chyme  Mixture of food, saliva, and gastric juices  Pancreatic amylase added as the chyme inter the duodenum  Intestinal villi  Most of the carbohydrate digestion occurs in the small intestine  Monosaccharides: Once hydrolyzed to monosaccharides, they are absorbed by the gut and transported to the liver by the hepatic portal venous blood supply.  Glucose is the only carbohydrate able to be used directly for energy or stored as glycogen GI Normal Physiology  Carbohydrate digestion:  Role of liver in Carbohydrate:  Maintenance of normal blood glucose levels over both short (hours) and long (days to weeks) periods is one particularly important function of the liver.  Excess glucose entering the blood after a meal is rapidly taken up by the liver and sequestered as glycogen.  The process of converting glycogen to glucose is glycogenolysis when blood glucose is low.  The process of converting glucose to glycogen is glycogenesis when blood glucose is high (insulin).  The liver can also convert other organic molecules, such as lipids and proteins, into glucose, if needed by the body for energy (gluconeogenesis). GI Normal Physiology  Protein digestion:  Proteins break down to peptides and amino acids  Begins in the stomach:  The chief cells in the stomach secrete pepsinogen, which is converted to pepsin by the hydrochloric acid, followed by series of digestive enzyme (e.g., trypsin, peptidase).  Completed in duodenum  Villi absorb amino acids  Functions of liver:  Deaminating amino acids, forming and excreting urea nitrogen, and synthesizing proteins, including albumin and enzymes. GI Normal Physiology  Lipid Digestion:  Lipids are not soluble in water  Cholecystokinin from small intestine slow motility and enhance fat digestion  Bile emulsifies fat (forms micelles) in the duodenum  Pancreatic and intestinal secrete lipase micelles  Triacylglycerols to monoacylglycerols and fatty acids  Role of the liver:  The liver is the major site for converting excess carbohydrates and proteins into fatty acids and triglyceride, which are then exported and stored in adipose tissue.  liver assists in the transportation process by synthesizing albumin, which helps transport fatty acids, and lipoproteins, which help transport most other lipids GI Normal Physiology  Digestion process: GI Diseases  Peptic Ulcers:  A peptic ulcer is a mucosal break of 3 mm in diameter in the stomach or duodenum.  Some untreated ulcers may continue to erode the mucosal layer and eventually form a hole through the stomach or duodenum.  Duodenal and gastric ulcers can be caused by Helicobacter (H. pylori) pylori. National Cancer Institute  H. pylori stimulates the inflammatory process, thus increasing the chances of intestinal lining erosion GI Diseases  Peptic Ulcers:  Laboratory test:  Gastroscopy: uses an endoscope to view the stomach and take tissue samples from an inflamed area  Breath test: patients drink a urea solution containing radioactively labeled carbon atoms (14C or 13C). If urease- producing H. pylori is present, the urea will be broken down by the bacterial urease, and the 14C or 13C will be incorporated and measured into carbon dioxide molecules  Serology tests: are used to detect antibodies (IgG, IgA, and IgM) to H. pylori  Stool test: is antigen test used to detect active or recent infection by H. pylori.  The American Gastroenterological Association recommend the urease breath and stool antigen tests. GI Diseases  Zollinger-Ellison Syndrome:  Is a condition characterized by benign, non–β-islet cell, gastrin-secreting tumors (gastrinomas)  located in the pancreas or duodenum.  These tumors stimulate excessive hydrochloric acid production by the parietal cells in the stomach, leading to the formation of peptic ulcers in the stomach and duodenum.  Over time, these gastrinomas may become malignant  Symptoms:  Include sever peptic ulcers, massive gastric hypersecretion, diarrhea, and steatorrhea (high fat in the stool). GI Diseases  Zollinger-Ellison Syndrome:  Diagnostic test:  Gastrin level measurement.  The patient must fast for 12 hours prior to the test.  Gastrin levels can be as high as 10 times the reference range (less than 100 pg/mL).  Tubes containing heparin should be used to collect blood specimens.  The specimen should be collected, transported, separated, and frozen within 15 minutes of collection.  Imaging techniques GI Diseases  Diarrhea:  Characterized by loose, watery, and frequent stools.  If persistent, it can lead to dehydration due to large water loss and dangerously low potassium levels resulting in serious complications or even death  Acute:  Short lived and self-limiting  The causes of acute diarrhea are divided into bacterial, viral, or parasitic causes  Broad-spectrum antimicrobials can destroy the normal gut bacteria and allow opportunistic bacteria to multiply, causing diarrhea GI Diseases  Diarrhea:  Chronic:  Chronic diarrhea can persist for weeks (>4), months, or longer; leads to dehydration and low level of K+  The primary causes of chronic diarrhea are ulcerative colitis and Crohn disease, irritable bowel syndrome, celiac disease, malabsorption, food intolerances, and chemotherapy or radiation GI Diseases  Diarrhea:  Laboratory tests:  Many laboratory tests are available to diagnosis diarrhea, including: A. Stool cultures B. immunoassays (ELISAs)  detect the presence of the infectious agent without culturing C. Ova and parasites  detects the presence of parasites and their eggs (ova) in stool GI Diseases  Inflammatory Bowel Disease (IBD):  IBD includes ulcerative colitis and Crohn disease  Ulcerative colitis: produces inflammation of the colon  Crohn disease: produces inflammation primarily in the small intestines, although it can also affect any place in the GI tract  Both ulcerative colitis and Crohn disease exhibit bouts of remission and bouts of exacerbation or “flare-ups.”  The causes of ulcerative colitis and Crohn disease are not known. Both appear to have autoimmune components  Possible autoimmune connection, genetic component, and environmental factors as well  Symptoms:  Both ulcerative colitis and Crohn disease are associated with abdominal pain, cramping, anorexia, bloody diarrhea, and anemia GI Diseases  Inflammatory Bowel Disease:  Diagnostic tests:  Although there are no specific tests to diagnose either ulcerative colitis or Crohn disease, there are assays currently being used:  Complete blood count (CBC):  Showing anemia or an increased white blood cell count.  Fecal examinations:  White blood cells can signify infection or inflammation, whereas red blood cells are indicative of bleeding.  Imaging and endoscopy:  CT and MRI are also used to diagnose IBD conditions GI Diseases  Inflammatory Bowel Disease:  Diagnostic tests:  Reference laboratories offer an IBD panel, which include:  Antineutrophil Cytoplasmic Antibodies (ANCA) assay  Autoantibodies are proteins made by your immune system that mistakenly target normal tissues  Myeloperoxidase (MPO) antibody test  Myeloperoxidase is associated with “classical” inflammatory responses in various inflammatory diseases  Proteinase-3 antibody test  An enzyme released during neutrophilic inflammation  Saccharomyces cerevisiae IgG and IgA antibody tests  The Saccharomyces cerevisiae IgG and IgA antibody tests can be positive in either condition GI Diseases  Malabsorption Syndrome:  The absorption defect can be associated with a single nutrient or all nutrients  Single nutrient deficiency  Lactase deficiency  All nutrients  Celiac disease and Crohn disease  Symptoms:  diarrhea, abdominal discomfort, and weight loss GI Diseases  Malabsorption Syndrome:  Laboratory tests:  A CBC is used to assess anemia; if present, iron studies, vitamin B12 and folate levels may be ordered.  Pancreatic elastase is used to assess pancreatic function  Celiac serology tests can help diagnose the disease. The current protocol is both IgG and IgA antibody testing for tissue transglutaminase (tTG) antibodies and gliadin antibodies  D-xylose absorption test  D-xylose is normally easily absorbed by the intestines. Level is low when is not absorbed by the intestines GI Diseases  Diverticulosis and Diverticulitis:  Diverticulum  Pouches in large intestine  Diverticulosis occurs when small, bulging pouches (diverticula) develop in colon  When one or more of these pouches become inflamed or infected, the condition is called diverticulitis  Diverticulosis and diverticulitis together are called diverticular disease  Diagnostic test:  CBC to detect inflammation  CT scan to visualize GI Diseases  Steatorrhea:  Excess fat in stools  usually associated with a greasy or oily appearance of the stools  Causes  pancreatic enzymes  cystic fibrosis  malabsorption, celiac disease  bacterial overgrowth in the bowel  decrease in bile acids GI Diseases  Steatorrhea:  Laboratory tests:  Fecal fat test  Samples will be stained with Sudan III to stain fat droplets in stool under microscope  Quantitative measurements use a 72-hour stool collection. The stool is well mixed and then analyzed to determine its fat content. The reference range for fecal fat is less than 7 g/day in stool. GI Diseases  Tropical Sprue and Celiac Sprue: Rye  Both lead to malabsorption  Tropical sprue from overgrowth of bacteria  bacterial condition seen in residents of, or visitors to, tropical areas  Celica sprue  an autoimmune disease in which the body produces antibodies to gluten (a component of wheat, barley, rye, and oats)  this results in an inflammatory state leading to malabsorption GI Diseases  Tropical Sprue and Celiac Sprue:  Laboratory tests:  Although the gold standard for diagnosing either disorder is a biopsy, this is left as a test of last resort.  Tropical sprue needs a positive stool culture to aid in the diagnosis.  Serologic testing are used to detect celiac disease.