Snapshot A 25-year-old man presents to his primary care physician for evaluation of diarrhea. He had recently gone to Mexico for spring break, where he stayed in a hostel with his friends. He spent a lot of time on the beach, swimming in caves, and hiking. He reports having onset of watery diarrhea about a week ago. He has not had any fevers, nausea, or vomiting. He does recall eating multiple rounds of raw oysters while in Mexico. He is found to be dehydrated, with poor skin turgor and dry mucous membrane. Introduction Overview acute diarrhea is characterized by acute onset of >3 bowel movements/day lasting <14 days and is often caused by infection persistent diarrhea lasts 2-4 weeks chronic diarrhea lasts >4 weeks and is often caused by underlying conditions such as inflammatory bowel disease or fat malabsorption Epidemiology incidence very common rotavirus is most common cause of infectious diarrhea worldwide vaccine available acute diarrhea is the second cause of childhood mortality in the world demographics viral diarrhea is most common in children especially rotavirus and adenovirus Etiology infections viruses bacteria parasites drug-induced quinidine colchicine cytotoxic agents chemotherapy food allergies toxic ingestions autoimmun small intestine bacterial overgrowth, often secondary to scleroderma or diabetes Pathogenesis types of diarrhea exudative/inflammatory diarrhea frequent, small-volume, and bloody stools indicates disrupted and inflamed mucosa etiologies infectious (i.e., Shigella, Salmonella, E. coli, Campylobacter, amebiasis) idiopathic inflammatory bowel disease (ulcerative colitis, Crohn disease) ischemic colitis fatty diarrhea weight loss and greasy or bulky stools that float that are often chronic etiologies fat malabsorption watery diarrhea osmotic diarrhea due to osmotic pull of water into the intestinal lumen etiologies giardiasis laxatives lactose intolerance secretory diarrhea due to active secretion of water etiologies infectious (i.e., enterotoxic E. coli, Vibrio) carcinoid syndrome gastrinoma drugs (i.e., colchicine) Infectious Bloody vs Watery Diarrhea Bloody Diarrhea Watery Diarrhea Campylobacter E. histolytica Enterohemorrhagic E. coli Enteroinvasive E. coli Non-thypoidal Salmonella Shigella Y. enterocolitica C. difficile C. perfringens Enterotoxigenic E. coli Giardia Cryptosporidium V. cholerae Rotavirus Norovirus Adenovirus S. aureus High Yield Risk Factors Exposure Risk Factors Associated Organisms Daycare Rotavirus, astrovirus, calicivirus, Campylobacter, Shigella, Giardia, Cryptosporidium Food Dairy Campylobacter, Salmonella Eggs Salmonella Beef E. coli Poultry Campylobacter, Salmonella Pork C. perfringens, Y. enterocolitica Seafood Astrovirus, Vibrio Oysters Calicivirus, Vibrio Rice/pasta Bacillus cereus Water exposure Swimming pools Shigella Contaminated water with cysts Giardia, E. histolytica, Cryptosporidium Travel history "Traveler's" diarrhea E. coli, Giardia, Salmonella, Shigella, Campylobacter Camping/hiking Giardia Past medical history Antibiotics/hospitalization C. difficile, rotavirus Pets Dog feces Yersinia enterocolitica Turtles/reptiles Non-typhoidal Salmonella Other animals/pets Campylobacter Presentation Symptoms common symptoms dehydration lethargy feeling of thirst diarrhea foul-smelling along with stools that float bloody diarrhea watery diarrhea other enteric symptoms nausea vomiting abdominal pain/cramping Physical exam inspection dry mucous membranes sunken eyes poor skin turgor delayed capillary refill Studies Acute diarrhea does not routinely require laboratory evaluation, unless clinical presentation includes high fever bloody diarrhea severe abdominal pain requires hospitalization elderly immunocompromised status Serum labs complete blood count Stool studies ova and parasite examination C. difficile toxin leukocyte presence suggests enteroinvasive infection pH <5.5 usually indicates viral illness and can also indicate lactase deficiency culture enzyme immunoassay for rotavirus and adenovirus antigens latex agglutination assay for rotavirus Differential Chronic diarrhea, which lasts 4 weeks or more, suggests other etiologies, such as fat malabsorption syndrome Chronic Diarrhea Malabsorption syndromes Celiac disease Lactose intolerance Pancreatic insufficiency Diabetic neuropathy Inflammatory bowel disease Crohn disease Ulcerative colitis Other gastrointestinal causes Microscopic colitis Irritable bowel syndrome Endocrinological Carcinoid Gastrinoma Drug-induced Quinidine Colchicine Chemotherapy Other Severe combined immunodeficiency Arsenic poisoning Vitamin C toxicity Vitamin B3 deficiency Treatment Medical supportive care modalities oral rehydration intravenous rehydration electrolyte repletion antibiotics indication for bacterial etiologies causing moderate or severe diarrhea and not responsive to rehydration metronidazole or tinidazole for Giardia infections doxycycline for Vibrio cholera oral vancomycin for C. difficile infection anti-motility agents indication not indicated for infectious diarrhea modalities loperamide bismuth salicylate Complications Dehydration
QUESTIONS 1 of 3 1 2 3 Previous Next Lab Values Blood Hematologic Cerebrospinal Sweat, Urine, and BMI Blood, Plasma, Serum Reference Range ALT 8-20 U/L Amylase, serum 25-125 U/L AST 8-20 U/L Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL Calcium, serum (Ca2+) 8.4-10.2 mg/dL Cholesterol, serum Rec: < 200 mg/dL Cortisol, serum 0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h Creatine kinase, serum Male: 25-90 U/LFemale: 10-70 U/L Creatinine, serum 0.6-1.2 mg/dL Electrolytes, serum Sodium (Na+) 136-145 mEq/L Chloride (Cl-) 95-105 mEq/L Potassium (K+) 3.5-5.0 mEq/L Bicarbonate (HCO3-) 22-28 mEq/L Magnesium (Mg2+) 1.5-2.0 mEq/L Estriol, total, serum (in pregnancy) 24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL 28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL Ferritin, serum Male: 15-200 ng/mLFemale: 12-150 ng/mL Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250 pH 7.35-7.45 PCO2 33-45 mmHg PO2 75-105 mmHg Glucose, serum Fasting: 70-110 mg/dL2-h postprandial:<120 mg/dL Growth hormone - arginine stimulation Fasting: <5 ng/mLProvocative stimuli: > 7ng/mL Immunoglobulins, serum IgA 76-390 mg/dL IgE 0-380 IU/mL IgG 650-1500 mg/dL IgM 40-345 mg/dL Iron 50-170 μg/dL Lactate dehydrogenase, serum 45-90 U/L Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL Osmolality, serum 275-295 mOsmol/kd H2O Parathyroid hormone, serume, N-terminal 230-630 pg/mL Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L Phosphorus (inorganic), serum 3.0-4.5 mg/dL Prolactin, serum (hPRL) < 20 ng/mL Proteins, serum Total (recumbent) 6.0-7.8 g/dL Albumin 3.5-5.5 g/dL Globulin 2.3-3.5 g/dL Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h Thyroxine (T4), serum 5-12 μg/dL Triglycerides, serum 35-160 mg/dL Triiodothyronine (T3), serum (RIA) 115-190 ng/dL Triiodothyronine (T3) resin uptake 25%-35% Urea nitrogen, serum 7-18 mg/dL Uric acid, serum 3.0-8.2 mg/dL Hematologic Reference Range Bleeding time 2-7 minutes Erythrocyte count Male: 4.3-5.9 million/mm3Female: 3.5-5.5 million mm3 Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/hFemale: 0-20 mm/h Hematocrit Male: 41%-53%Female: 36%-46% Hemoglobin A1c ≤ 6 % Hemoglobin, blood Male: 13.5-17.5 g/dLFemale: 12.0-16.0 g/dL Hemoglobin, plasma 1-4 mg/dL Leukocyte count and differential Leukocyte count 4,500-11,000/mm3 Segmented neutrophils 54%-62% Bands 3%-5% Eosinophils 1%-3% Basophils 0%-0.75% Lymphocytes 25%-33% Monocytes 3%-7% Mean corpuscular hemoglobin 25.4-34.6 pg/cell Mean corpuscular hemoglobin concentration 31%-36% Hb/cell Mean corpuscular volume 80-100 μm3 Partial thromboplastin time (activated) 25-40 seconds Platelet count 150,000-400,000/mm3 Prothrombin time 11-15 seconds Reticulocyte count 0.5%-1.5% of red cells Thrombin time < 2 seconds deviation from control Volume Plasma Male: 25-43 mL/kgFemale: 28-45 mL/kg Red cell Male: 20-36 mL/kgFemale: 19-31 mL/kg Cerebrospinal Fluid Reference Range Cell count 0-5/mm3 Chloride 118-132 mEq/L Gamma globulin 3%-12% total proteins Glucose 40-70 mg/dL Pressure 70-180 mm H2O Proteins, total < 40 mg/dL Sweat Reference Range Chloride 0-35 mmol/L Urine Calcium 100-300 mg/24 h Chloride Varies with intake Creatinine clearance Male: 97-137 mL/minFemale: 88-128 mL/min Estriol, total (in pregnancy) 30 wks 6-18 mg/24 h 35 wks 9-28 mg/24 h 40 wks 13-42 mg/24 h 17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 hFemale: 2.0-8.0 mg/24 h 17-Ketosteroids, total Male: 8-20 mg/24 hFemale: 6-15 mg/24 h Osmolality 50-1400 mOsmol/kg H2O Oxalate 8-40 μg/mL Potassium Varies with diet Proteins, total < 150 mg/24 h Sodium Varies with diet Uric acid Varies with diet Body Mass Index (BMI) Adult: 19-25 kg/m2 Calculator ( ) xy AC 7 8 9 ÷ 4 5 6 × 1 2 3 - 0 . = + You have 100% on this question. Just skip this one for now. Take This Question Anyway (M1.GI.80) A 22-year-old female presents to your office with gas, abdominal distention, and explosive diarrhea. She normally enjoys eating cheese but has been experiencing these symptoms after eating it for the past few months. She has otherwise been entirely well except for a few days of nausea, diarrhea, and vomiting earlier in the year from which she recovered without treatment. Which of the following laboratory findings would you expect to find during workup of this patient? Review Topic | Tested Concept QID: 101137 Type & Select Correct Answer 1 Decreased stool osmolar gap 15% (10/66) 2 Decreased stool pH 70% (46/66) 3 Positive fecal smear for leukocytes 3% (2/66) 4 Positive stool culture for Rotavirus 5% (3/66) 5 Positive stool culture for T. whippelii 8% (5/66) M1 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 You have 100% on this question. Just skip this one for now. Take This Question Anyway (M1.GI.100) A 30-year-old male visits you in the clinic complaining of chronic abdominal pain and diarrhea following milk intake. Gastrointestinal histology of this patient's condition is most similar to which of the following? Review Topic | Tested Concept QID: 101157 Type & Select Correct Answer 1 Celiac disease 13% (9/71) 2 Crohns disease 0% (0/71) 3 Tropical sprue 3% (2/71) 4 No GI disease 83% (59/71) 5 Ulcerative colitis 0% (0/71) M1 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 You have 100% on this question. Just skip this one for now. Take This Question Anyway (M1.GI.7) A 24-year-old patient presents to your gastroenterology practice on a referral from her primary care provider. The patient has been experiencing postprandial bloating and abdominal pain for one year. Symptoms occur following the ingestion of milk products. Which of the following drugs has a mechanism of action that is similar to the pathophysiology of this patient's disease? Review Topic | Tested Concept QID: 101064 Type & Select Correct Answer 1 Omeprazole 4% (7/197) 2 Bismuth 10% (20/197) 3 Ranitidine 6% (11/197) 4 Octreotide 11% (21/197) 5 Magnesium hydroxide 66% (131/197) M1 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5