Diarrhea I/ Summary Diarrheal diseases are very common and, in most cases, self-limiting Diarrhea is defined either as the presence of more than three bowel movements per day, water content exceeding 75%, or a stool quantity of at least 200–250 g per day Acute diarrhea lasts for no longer than 14 days and is typically caused by viral or bacterial infection or food poisoning Chronic diarrhea is often caused by underlying gastrointestinal or endocrinological conditions, such as inflammatory bowel disease or hyperthyroidism Further symptoms may include fever, bloody stools, abdominal pain, and nausea and vomiting in cases of gastroenteritis Diagnostic tests for acute diarrhea are usually unnecessary, but they may include CBC, stool samples, or colonoscopy for severe or chronic cases Most cases of diarrhea only require symptomatic treatment, such as oral rehydration, while severe cases may necessitate administration of antibiotics and hospitalization for IV fluid replacement II/ Definition  Diarrhea is present if one of the following criteria is fulfilled: Frequent defecation: ≥ three times per day Altered stool consistency: water content > 75% Increase in stool quantity: more than 200–250 g per day  Acute diarrhea: lasting ≤ 14 days  Persistent diarrhea: lasting > 14 days  Chronic diarrhea: lasting > 30 days III/ Etiology Infectious causes Noninfectious Risk factors and disease transmission  Transmission by direct contact and droplets  Day care attendance, nursing home residency, hospitalization  Contaminated food and water (see traveler's diarrhea)  Animal exposure IV/ Classification Pathophysiology Associated disorders Exudativeinflammatory diarrhea  Damage to the intestinal mucosa may cause cytokineinduced water hypersecretion, impair absorption of osmotically active substances or fat, or disrupt water and electrolyte absorption  Mucus, blood, and leukocytes present in stool  Shigellosis, salmonellosis, enteroinvasive E coli, enterohemorrhagic E.coli, campylobacteriosis, amebiasis  Ulcerative colitis, Crohn disease Secretory diarrhea  Active secretion of water into the intestinal lumen via inhibition/activation of enzymes (e.g., ↑ cAMP activity)      Osmotic diarrhea  Water is drawn into the intestinal lumen by poorly absorbed substances (e.g., salt, sugar, laxatives)  Laxatives, citrate of magnesia  Malabsorption, lactose intolerance Motor diarrhea  Rapid intestinal passage due to increased bowel movements  Hyperthyroidism  Carcinoid syndrome  Drugs (e.g., erythromycin) !!! (Foodborne) infections (cholera, enterotoxigenic E coli) Endocrine tumors (e.g., carcinoid tumors, gastrinoma) Impaired absorption of bile acids/salts Malabsorption disorders or history of ilealresection Drugs (e.g., colchicine) The loss of bicarbonate-rich fluid in severe diarrhea may cause non-anion gap metabolic acidosis! V/ Clinical features  Acute or chronic diarrhea (see “Definition” above)  Further possible symptoms  Fever  Abdominal pain and cramping  Blood in stool  Nausea and vomiting in cases of gastroenteritis  Signs of dehydration in severe cases  Chronic cases: malnutrition and, in children, failure to thrive  Disease courses can range from mild to severe with need of hospitalization VI/ Subtypes and variants Traveler's diarrhea  Infections which typically occur in patients with a history of recent travel  Very common while traveling in Asian (“Delhi belly”), African, and Latin American countries ("Montezuma's Revenge")  A major cause of diarrhea among children in developing countries  May be exudative-inflammatory diarrhea or secretory diarrhea  Most commonly caused by enterotoxigenic Escherichia coli (ETEC)  Other pathogens: Campylobacter jejuni, Shigella spp., Salmonella spp., other E coli strains (e.g., EAEC), protozoa (e.g., Giardia), viral diarrhea (norovirus, rotavirus, astrovirus) Factitious diarrhea  Definition: self-induced diarrhea, usually by laxative abuse; often occurs in individuals with factitious disorders  Epidemiology  Most prevalent in women  Patients are usually employed in the health field  History of multiple hospital admissions  Clinical findings: chronic watery diarrhea without identifiable cause  Diagnosis  Laboratory tests: metabolic alkalosis, hypokalemia, hypermagnesemia  Colonoscopy: may show melanosis coli in cases of anthraquinone abuse  Treatment  Correction of electrolyte disturbances and dehydration  Referral to psychotherapy Laxative abuse  Substances  Bulking agent: flaxseed  Osmotic laxatives: lactulose, macrogols (polyethylene glycol), magnesium sulfate, sodium sulfate  Diphenolic laxatives: bisacodyl, sodium picosulfate  Anthraquinones: senna, aloe vera, rhubarb  Clinical features  Osmotic diarrhea, meteorism  Dehydration  Hypokalemia  Melanosis coli: benign hyperpigmentation of the colonic mucosa caused by anthraquinone abuse  Colonoscopy: dark brown pigmentation of the colon, interspersed with pale patches reflecting lymph follicles  Biopsy: lipofuscin-laden macrophages on PAS staining VII/ Diagnostics The workup for diarrhea includes a detailed patient history (e.g., recent travel), physical examination, and laboratory tests to assess severe cases Laboratory tests Laboratory tests are usually not required in acute cases and are instead reserved for diagnosis of severe or chronic disease  Indications  Diarrhea lasting > days  High fever  Blood in stools  Suspicion of IBD  Immunosuppression  Tests  CBC: may show anemia or leukocytosis  Stool samples: leukocytes; ova and parasites  Bacterial stool culture  Indications: suspicion of invasive bacterial enteritis, moderate to severe illness  C difficile toxin assay Imaging  Colonoscopy: in patients with chronic diarrhea without identifiable cause  CT: if diverticulitis or IBD is suspected VIII/ Treatment Since most cases of acute diarrhea are self-limited, treatment is mostly symptomatic, focusing on oral rehydration, and rarely requires medication  Rehydration (especially in children)  Mild to moderate dehydration: oral administration of electrolyte-containing fluids (e.g., apple juice or Pedialyte®)  Severe cases: consider hospitalization; hydration with IV sodium chloride at 0.9%  Antidiarrheal agents (e.g., loperamide): may be given in mild to moderate cases; should be avoided if there is fever or blood in stools (indicative of systemic disease)  Antibiotics: are generally not indicated  Treatment of the underlying condition in cases of chronic diarrhea QUESTION Q1 A 28-year-old man comes to the physician because of diarrhea and crampy abdominal pain for weeks He has had up to bowel movements per day Several times he noticed mucoid strings with the stool He has abdominal bloating Over the past month, has had a 3.2kg (7-lb) weight loss He has not had fever, cough, or bloody stools He had a painful rash on his lower extremity weeks ago that resolved spontaneously He works as a pharmacy technician His temperature is 37.3°C (98.8°F), pulse is 85/min, and blood pressure is 115/77 mm Hg The abdomen is soft and nontender His hemoglobin concentration is 11.9 g/dL, MCV is 79 fL, ferritin is 106 ng/dL, and platelet count is 410,000/mm3; serum concentrations of glucose, creatinine, and electrolytes are within the reference range This patient's condition is most likely associated with which of the following findings? A Mucosal lactase deficiency B Increased serum VIP C Stool leukocytes D Accelerated colon transit E Melanosis coli F Normal intestinal mucosa Q2 A 4-week-old male infant is brought to the physician because of a 1-week history of refusing to finish all his bottle feeds and becoming irritable shortly after feeding He has also spit up sour-smelling milk after most feeds Pregnancy and delivery were uncomplicated, with the exception of a positive vaginal swab for group B streptococci weeks ago, for which the mother received one dose of intravenous penicillin The baby is at the 70th percentile for length and 50th percentile for weight His temperature is 36.6°C (98°F), pulse is 180/min, respirations are 30/min, and blood pressure is 85/55 mm Hg He appears lethargic Examination shows sunken fontanelles and a strong rooting reflex The abdomen is soft with a 1.5-cm (0.6-inch) nontender epigastric mass Examination of the genitals shows a normally pigmented scrotum, retractile testicles that can be pulled into the scrotum, a normal-appearing penis, and a patent anus Which of the following interventions would have been most likely to decrease the patient's risk of developing his condition? A Feeding of soy milk formula B Breastfeeding only C Avoiding penicillin administration to the mother D Treating the infant with glucocorticoids E Performing cesarean section Q3 A 62-year-old man is brought to the emergency department with fatigue, dry cough, and shortness of breath for days He reports a slight fever and has also had episodes of watery diarrhea earlier that morning Last week, he attended a business meeting at a hotel and notes some of his coworkers have also become sick He has a history of hypertension and hyperlipidemia He takes atorvastatin, hydrochlorothiazide, and lisinopril He appears in mild distress His temperature is 102.1°F (38.9°C), pulse is 56/min, respirations are 16/min, and blood pressure is 150/85 mm Hg Diffuse crackles are heard in the thorax Examination shows a soft and nontender abdomen Laboratory studies show: Hemoglobin 13.5 g/dL Leukocyte count 15,000/mm3 Platelet count 130,000/mm3 Serum Na+ 129 mEq/L Cl100 mEq/L K+ 4.6 mEq/L HCO322 mEq/L Urea nitrogen 14 mg/dL Creatinine 1.3 mg/dL An x-ray of the chest shows infiltrates in both lungs Which of the following is the most appropriate next step in diagnosis? A Direct immunofluorescent antibody test B Stool culture C Lung biopsy D Serum immunoglobulin testing E Polymerase chain reaction F CT Chest G Urine antigen assay Q4 A 19-year-old woman comes to the physician because of a 1-year history of severe abdominal pain, bloating, and episodic diarrhea She has also has a 10-kg (22-lb) weight loss over the past 10 months Physical examination shows a mildly distended abdomen, diffuse abdominal tenderness, and multiple erythematous, tender nodules on the anterior aspect of both legs There is a small draining lesion in the perianal region Further evaluation of this patient's gastrointestinal tract is most likely to show which of the following findings? A Villous atrophy B Crypt abscesses C No structural abnormalities D Melanosis coli E Neuroendocrine tumor cells F Transmural inflammation Q5 A 38-year-old woman comes to the physician because of persistent diarrhea and fatigue for month She has had up to 12 watery stools per day Sometimes she awakens at night because she has to defecate She has abdominal bloating and cramps She has had a 2-kg weight loss in the past month She returned from a trip to Costa Rica weeks ago She has a history of bronchial asthma and bulimia nervosa She works as a nurse She does not smoke and drinks 1–2 beers on the weekend Current medications include fish oil, a multivitamin, and a salbutamol inhaler Her temperature is 36.8°C (98.2°F), pulse is 65/min, and blood pressure is 100/75 mm Hg Examination shows dry mucous membranes Abdominal and rectal examinations are unremarkable Laboratory studies show: Hematocrit 46% Leukocyte Count 6,500/mm3 Platelet Count 220,000/mm3 Serum Na+ 136 mEq/L K+ 3.2 mEq/L Cl- 102 mEq/L HCO3- 33 mEq/L Mg2+ 2.3 mEq/L Urea nitrogen 14 mg/dL Creatinine 0.8 mg/dL Abdominal ultrasound shows no abnormalities Colonoscopy shows dark colored mucosa with interspersed white spots Biopsies of colonic mucosa are obtained and sent for pathological evaluation Which of the following is the most likely underlying cause of this patient's symptoms? A Celiac disease B Carcinoid tumor C Gastrointestinal stromal tumor D VIPoma E Irritable bowel syndrome F Enterotoxigenic Escherichia coli G Medication abuse H Amebiasis ANSWER: 1C 2B 3G 4F 5G ... countries ("Montezuma's Revenge")  A major cause of diarrhea among children in developing countries  May be exudative-inflammatory diarrhea or secretory diarrhea  Most commonly caused by enterotoxigenic... strains (e.g., EAEC), protozoa (e.g., Giardia), viral diarrhea (norovirus, rotavirus, astrovirus) Factitious diarrhea  Definition: self-induced diarrhea, usually by laxative abuse; often occurs... Colonoscopy: in patients with chronic diarrhea without identifiable cause  CT: if diverticulitis or IBD is suspected VIII/ Treatment Since most cases of acute diarrhea are self-limited, treatment