Intestines Flashcards
3 potential complications of Celiac Disease?
- Refractory Sprue
(persisting symptoms and histological injury despite being on diet for 12 months) - Intestinal Adenocarcinoma
- T cell lymphoma
Gliadin is deaminated by ___a___ in the __b__ of the small intestine which facilitates gliadin’s ability to interact w/ __b__ & __b__ located on the surface of Antigen Presenting Cells
a) Tissue Transglutaminase (TTG)
b) HLA-DQ2 & HLA-DQ8
Celiac Disease: Clinical Presentation?
- Diarrhea
- Weight loss
- Failure to thrive
- Short stature
- Anemia (Iron, Folate, B12 deficiencies)
- Bone disease (vit. D deficiency)
(many patients remain asymptomatic
Celiac Disease: Treatment?
- Gluten-free diet (70-90% respond)
- Vitamins & Minerals (iron, folate, Vitamins D, B12)
- Screen for Bone Injury: densiometry
- Screen Family for Celiac Disease (DQ2, DQ8)
Celiac Disease: Diagnosis
Endoscopy findings?
- Scalloping of duodenal folds
- Flattened/absent villi
- Mosaic appearing surface of mucosa
- May be normal appearing (always take 4-6 biopsies when suspicious)
Celiac Disease: Diagnosis Histopathologic findings?
- Increased intraepithelial lymphocytes
- Increased lymphocytes and plasma cells in the lamina propria
- Absent or blunted villi
- Elongated Intestinal crypts
Celiac Disease: Diagnosis
Serology findings?
- Anti-endomyoseal IgA antibody *
- TTG IgA antibody**
- Anti-gliadin IgA &/or IgG antibody
- Deaminated gliadin peptide
- HLA-DQ2, DQ8
Define the following:
1. Gluten
2. Gliadin
3. Alfa fraction
- Gluten: the protein component of wheat, barley and rye.
- Gliadin: the alcohol soluble portion of digested gluten.
- Alfa fraction: the portion of gliadin able to pass the mucosal barrier of the intestine.
Folic acid deficiency results in _____ anemia.
macrocytic
A gluten free diet results in the resolution of which of the following?
a. patient’s symptoms b. positive serology
c. abnormal histology
All of them
T or F? Iron deficiency may be the only sign of Celiac disease.
True
Vitamin A deficiency results in..?
Night blindness, conjunctival dryness, and keratomalacia
Vitamin D deficiency results in..?
Osteomalacia: Clinically manifests as muscle weakness and musculoskeletal pain
- Osteopenia and osteoporosis
Vitamin E deficiency results in..?
Hemolytic anemia, gait disturbance, and neuropathy
Vitamin K deficiency results in..?
Prolonged prothrombin time, resulting in decreased synthesis of clotting factors II, VII, IX, and X
Sucrose = ____ & ____
Glucose & Fructose
Lactose = ____ & ____
Glucose & gaLACTOSE
Absorbed products of lipolysis, once in the enterocytes, are synthesized into __(a)__ and exit as __(b)__ into lymph lacteals.
a) Triglycerides
b) Chylomicrons
(Chylomicron = Triglyceride + Apolipoproteins)
Once chyme reaches the cecum, _____ is released & this stops the process of CCK release.
What are some effects of this further inhibition of CCK release?
Peptide YY
Decreased:
- Gastric acid secretion & Gastric emptying
- Pancreatic secretion
- Colonic motility
3 functions of intestine in between meals?
- Propulsion- Motilin stimulates migrating motor complexes to move stuff out of SI
- Retention- Luminal distention triggers stretch receptors to initiate the anorectal inhibitory reflex to preserve continence
- Defecation- Involuntary (internal anal sphincter is relaxed) & Voluntary (external relaxed)
D-xylose test is most helpful in distinguishing..?
Maldigestion (pancreatic insufficiency) from Malabsorption (celiac sprue)
How do you interpret a d-Xylose test?
d-Xylose Excretion:
- Normal in Maldigestion
- Dec’d in Malabsorption
Fecal Fat:
- Inc’d in Maldigestion & Malabsorption
Jejunal Biopsy:
- Normal in Maldigestion
- Abnormal/”flat” in Malabsorption
Schilling Test evaluates..?
possible B12 deficiency
Schilling Test, for each step:
What is done?
If B12 corrects @ this step, Dx is..?
- Give parenteral B12 for loading, then radio-labeled B12
Dx = Dietary deficiency - Radio-labeled B12 given w/ Intrinsic Factor
Dx = Pernicious Anemia - Repeat w/ enzymes
Dx = Pancreas problem - Repeat w/ antibiotics
Dx = Bacterial overgrowth - Ileum problem
Diarrhea definition by stool weight or stool water is an increase in how much?
Increase in stool weight or water > 150-200 gm/24hr
WHO definition: “Diarrhoea is the passage of 3 or more loose or liquid stools per day, or more frequently than is normal for the individual.”
Lower GI bleed- dDx?
- Neoplasm (Polyps, Colorectal adenocarcinoma)
- Colitis
- Infectious Diarrhea (E.coli, Shigella, Salmonella, C. jejuni)
- Diverticular Disease
- Hemorrhoids
Diarrhea:
Classification/Types?
- Secretory
- Osmotic
- Exudative
- Malabsorptive
- Abnormal motility
Water absorption occurs due to the osmotic gradient established by __(a)__ - which itself is dependent on absorption of __(b)__ & __(c)__.
a) Sodium
b) Glucose
c) Amino Acids
(primary mechanism of Na+ absorption is cotransport w/ glucose & AAs)
Simplified diarrhea classifications involved in:
- Watery diarrhea
- Bloody diarrhea
- Fatty diarrhea
Watery:
- Osmotic
- Secretory
- Motility Disorders
- Infectious
Bloody:
- Exudative/inflammatory
- Infectious
Fatty:
- Malabsorptive
- Motility disorders
Secretory Diarrhea - Features?
- Stool isotonic w/ plasma
- Large volume diarrhea (>1L/day)
- Diarrhea persists when fasting
- Electrolytes account for most of stool osmolality (which is small, <50)
_______ is the classic secretory diarrhea (etiology)
Vibrio Cholera
Vibrio Cholera - does organism colonize intestinal cells?
No, it sticks to the surface of small bowel cells, w/out ever penetrating the mucosal surface, & produces its enterotoxin
How does Vibrio Cholera cause diarrhea?
- Produces an enterotoxin (protein) that enters enterocytes in the SI
- Irreversibly activates Adenylate Cyclase
- Na/Cl absorption is inhibited & anions are secreted, causing Secretory diarrhea
Does Vibrio Cholera cause intestinal damage?
No, it does not invade cells – its toxin does but does not destroy them
Diagnosis?
Severe “rice water” stool output (>1L/day)
Vibrio Cholera
Tx for Vibrio Cholera that dramatically improves mortality?
Oral solution w/ glucose (& pinch of sodium)
- enhances sodium absorption via sodium-glucose cotransport
Hormone producing tumors that cause secretory diarrhea?
- Carcinoid (5HT, Prostaglandins, Bradykinin)
- VIPoma (VIP)
- Gastrinoma (Gastrin)
- Medullary Carcinoma of Thyroid (Calcitonin, Prostaglandins)
- Ganglioneuroma (probably VIP)
Carcinoid Syndrome- what type of diarrhea can this cause & how?
Secretory diarrhea, caused by increased production & metabolism of Tryptophan, leading to increased 5HT
- 5HT causes secretory diarrhea via anion secretion & Na/Cl inhibition
Osmotic diarrhea- pathophysiology?
Poorly absorbed solutes creates osmotic gradient that draws water into intestinal lumen
- Failure to transport osmotically active solute
Osmotic diarrhea- Causes?
- Magnesium (in laxatives)
- Lactose ingestion w/ lactase deficiency
Osmotic diarrhea- Features?
- Stool volume typically 125
- Acidic stool pH from carbohydrate malabsorption
- Unmeasured non-electrolytes account for most of stool osmolality (which is large, >125)
3 Diagnostic methods of Lactase deficiency?
- Trial of milk produce ingestion w/ & w/out lactase enzyme supplement
- Hydrogen breath test: Lactose hydrogen (H2) absorbed into portal circulation & excreted in breath (rise in exhaled hydrogen >20ppm)
- Lactose Tolerance Test: Ingest 50 mg lactose, blood glucose rises <20 mg/dL
Examples of Motility disorders causing diarrhea?
- IBS
- Scleroderma
- Intestinal surgery predisposing to bacterial overgrowth syndrome
Examples of Edudative diarrhea?
IBD:
- Crohn’s Disease
- Ulcerative Colitis
Infectious:
- Shigella
- Clostridium dificile
- Entamoeba Histolytica
Classic malabsorptive diarrhea symptoms?
Steatorrhea & weight loss
- Large volume stools
- Malodorous & fat droplets
Complications of malabsorptive diarrhea?
- Fat soluble vitamin deficiencies
- Edema &/or ascites
Giardia causes a ______ diarrhea
malabsorptive
Giardia diarrhea- Features?
Trophozoites
- attach via adhesive disk on ventral surface
- reside in proximal small bowel
- no cellular invasion or necrosis
- Inflammatory response causes changes to villous & crypt architecture
- Disruption of microvilli & brush border enzymes
- No cleare enterotoxin
Whipple’s Disease- etiology?
Chronic systemic infection
- Tropheryma whippelii
- PAS-positive, bacteria-laden macrophages in lamina propria of small intestine
- Macrophage infiltration of mucosa & obstruction of mesenteric lymph nodes leads to malabsorption
- SI most commonly affected
- – Joints, CV system, CNS
3 types of diarrhea-causing E. coli?
Bloody diarrhea:
- Enterohemorrhagic E. coli (EHEC)
- – O157:H7 strain in US, usually affects children
- – Shiga-like toxin, can cause HUS
- Enteroinvasive E. coli (EIEC)
- – invades colonic mucosa
Watery diarrhea:
- Enterotoxigenic E. coli
- – Traveler’s diarrhea & Infantile diarrhea
- – Produces ST & LT Toxins
- – Cramps, occasional vomiting, low-grade fever
Causative Organism?
- Bloody diarrhea
- Comma or S-shaped organisms, growth @ 42F
Campylobacter
Causative Organism?
- Bloody diarrhea caused by Protozoan
Entamoeba Histolytica
Causative Organism(s)? - Watery diarrhea caused by Protozoa
- Giardia (cysts in stool, Tx = Metronidazole or Nitazoxanide)
- Cryptosporidium (immunocompromised – must order specific exam for Dx; Tx = Nitazoxanide)
Causative organism?
- Bloody diarrhea
- Day-care outbreaks, psuedoappendicitis
Yersinia enterocolitica
It is appropriate to obtain endoscopic biopsies looking for celiac disease in patients w/ what 4 symptoms/conditions?
- Positive Serologic test
- Iron deficiency Anemia
- Chronic diarrhea
- Weight loss
Villous atrophy is found in a number of GI diseases.
Name 5 of them.
- Celiac Disease
- Whipple’s Disease
- Tropical Sprue
- Intestinal Lymphoma
- Crohn’s Disease
