Snapshot A 12-year-old boy is brought to the clinic for diarrhea and vomiting. He has no fever but complains of intermittent, cramping, and abdominal pain. They just returned from a family picnic, where about two hours ago the child ate potato salad. The mother reports other family members had become ill after the meal as well. Introduction Definitions stool with increased water content, volume, or frequency (> 250 grams/day of stool) cause of 2.5 million deaths per year worldwide in US, an estimated 48 million foodborne diarrheal illnesses occur annually Classifications timecourse acute diarrhea lasts less than 14 days persistent diarrhea lasts 2 - 4 weeks chronic diarrhea lasts > 4 weeks types invasive/inflammatory non-invasive, non-inflammatory osmotic diarrhea secretory diarrhea Differential diagnosis depends on both time course and type of diarrhea infectious causes include: viruses bacteria parasites for full list of bugs causing diarrhea, see Microbiology topic noninfectious causes include: medication adverse effects acute abdominal processes gastroenterologic disease endocrine disease General approach - 5 criteria to consider does the patient really have diarrhea? beware of fecal incontinence and impaction rule out medications as a cause of diarrhea (drug-induced diarrhea) distinguish acute from chronic diarrhea. categorize the diarrhea as inflammatory, fatty, or watery. consider factitious diarrhea. Pathophysiology Invasive, inflammatory diarrhea history characterized by frequent, small-volume, bloody stools may be accompanied by tenesmus, fever, or severe abdominal pain fundamentally indicates disrupted and inflamed mucosa causes infectious processes (i.e., Shigella, Campylobacter jejuni, Entamoeba histolytica, Salmonella enterensis, Entero-hemorrhagic E. coli, Clostridium difficile, cytomegalovirus, tuberculosis) idiopathic inflammatory bowel disease (i.e., Crohn's, Ulcerative Colitis) ischemic colitis Fatty diarrhea history of weight loss, greasy or bulky stools that are difficult to flush, and oil in the toilet bowl that requires a brush to remove results from: fat malabsorption (inadequate mucosal transport) i.e., celiac disease fat maldigestion (defective hydrolysis of triglycerides) pancreatic exocrine insufficiency (i.e., chronic pancreatitis) inadequate duodenal bile acid concentration (i.e., small intestinal bacterial overgrowth [SIBO] or cirrhosis) Watery diarrhea osmotic diarrhea loss of large volumes of diarrhea without inflammation of the enterocytes osmotically active substance drawing hypotonic solution into the lumen caused by ingestion of poorly absorbed ions or sugars stool volume decreases with fasting causes: giardiasis laxatives (e.g., magnesium containing products) lactose intolerance (e.g., lactase deficiency) Secretory diarrhea loss of large volumes of isotonic, watery diarrhea without inflammation of the enterocytes caused by disruption of epithelial electrolyte transporters stool volume continues unabated with fasting causes infection enterotoxin production by ETEC, Vibrio cholera stimulates Cl- channel via ↑ cAMP non-osmotic laxative use phenanthracene use can cause melanosis coli peptide-secreting endocrine tumors carcinoid syndrome increased production of 5-HT by tumor Presentation Symptoms abdominal pain and cramping frequent and profuse stools Evaluation In the vast majority of cases, work-up of acute diarrheal illness is not necessary, as most causes of diarrhea are self-lmited Indications for increased severity requiring further evaluation: profuse watery diarrhea with signs of hypovolemia bloody diarrhea temperature ≥ 38.5ºC (101.3ºF) passage of ≥ 6 unformed stools per 24 hours or a duration of illness > 48 hours severe abdominal pain hospitalized patients or recent use of antibiotics elderly (≥ 70 years of age) immunocompromised systemic illness with diarrhea, especially in pregnant women Invasive diarrhea findings stool culture stool smear (+) for fecal leukocytes CRP, ESR often elevated low serum albumin level Fatty diarrhea findings Sudan stain - positive test indicates presence of steatorrhea endoscopy or CT scan may be required to identify structural problem involving the small intestine or pancreas Osmotic diarrhea findings stool osmotic gap > 50 consistent with osmotic type stool smear (-) for fecal leukocytes decreased stool pH seen in lactase deficiency Secretory diarrhea findings stool osmotic gap < 50 excludes osmotic type stool smear (-) for fecal leukocytes look for ↑ 5-HIAA as a degradation product of 5-HT in carcinoid syndrome if positive, further imaging will be required microscopy no abnormal morphology evidenced Treatment Pharmacologic oral rehydration therapy components include water, glucose, sodium in most diarrheal illnesses, intestinal glucose absorption via sodium-glucose cotransport remains intact antidiarrheal agents loperamide and bismuth salicylate dietary modifications boiled starches and cereals (e.g., potatoes, noodles, rice, wheat, oats) with salt avoidance of foods with high-fat content antimicrobials consider empiric treatment for patients with severe illness (as described under Evaluation) if organism identified, can tailor treatment, i.e.,: TMP-SMX for severe E. coli diarrhea metronidazole for G. lamblia Prevention consistent hand-hygiene techniques prudent selection of food and drink while traveling food that has been thoroughly cooked and served hot fruits that the traveler peels just prior to eating pasteurized dairy products water sanitation
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 . = + (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 QID: 101157 1 Celiac disease 25% (5/20) 2 Crohns disease 0% (0/20) 3 Tropical sprue 5% (1/20) 4 No GI disease 70% (14/20) 5 Ulcerative colitis 0% (0/20) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (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 QID: 101064 1 Omeprazole 3% (4/129) 2 Bismuth 9% (11/129) 3 Ranitidine 7% (9/129) 4 Octreotide 11% (14/129) 5 Magnesium hydroxide 67% (87/129) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (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 QID: 101137 1 Decreased stool osmolar gap 24% (4/17) 2 Decreased stool pH 59% (10/17) 3 Positive fecal smear for leukocytes 0% (0/17) 4 Positive stool culture for Rotavirus 12% (2/17) 5 Positive stool culture for T. whippelii 6% (1/17) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 2