Acute diarrhea and weight loss differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]

Differential Diagnosis of Acute Diarrhea and Weight Loss from other diseases

The following table outlines the major differential diagnoses of acute diarrhea and weight loss.

Abbreviations: GI: Gastrointestinal, CBC: Complete blood count, WBC: White blood cell, RBC: Red blood cell, Plt: Platelet, Hgb: Hemoglobin, ESR: Erythrocyte sedimentation rate, CRP: C–reactive protein, IgE: Immunoglobulin E, IgA: Immunoglobulin A, ETEC: Escherichia coli enteritis, EPEC: Enteropathogenic Escherichia coli, EIEC: Enteroinvasive Escherichia coli, EHEC: Enterohemorrhagic Escherichia coli, EAEC: Enteroaggregative Escherichia coli, Nl: Normal, ASCA: Anti saccharomyces cerevisiae antibodies, ANCA: Anti–neutrophil cytoplasmic antibody, DNA: Deoxyribonucleic acid, CFTR: Cystic fibrosis transmembrane conductance regulator, SLC10A2: Solute carrier family 10 member 2, SeHCAT: Selenium homocholic acid taurine or tauroselcholic acid, IEL: Intraepithelial lymphocytes, MRCP: Magnetic resonance cholangiopancreatography, ANA: Antinuclear antibodies, AMA: Anti-mitochondrial antibody, LDH: Lactate dehydrogenase, CPK: Creatine phosphokinase, PCR: Polymerase chain reaction, ELISA: Enzyme–linked immunosorbent assay, LT: Heat–labile enterotoxin, ST: Heat–stable enterotoxin, RT-PCR: Reverse–transcriptase polymerase chain reaction, CD4: Cluster of differentiation 4, HIV: Human immunodeficiency virus, RUQ: Right-upper quadrant, VIP: Vasoactive intestinal peptide, GI: Gastrointestinal, FAP: Familial adenomatous polyposis, HNPCC: Hereditary nonpolyposis colorectal cancer, MTP: Microsomal triglyceride transfer protein, Scl‑70: Anti–topoisomerase I, TSH: Thyroid-stimulating hormone, T4: Thyroxine, T3: Triiodothyronine, DTR: Deep tendon reflex, RNA: Ribonucleic acid

Cause		Clinical manifestation									Lab findings									Extra intestinal findings	Cause/Pathogenesis	Gold standard diagnosis
		Symptoms								GI signs
		Duration		Diarrhea			Fever	Abdominal pain	Weight loss
											Stool exam					CBC			Other lab findings
		Acute	Chronic	Watery	Bloody	Fatty					WBC	RBC	Ova/Parasite	Osmotic gap	Other	WBC	Hgb	Plt
Ischemic colitis		+	+	+	+	–	+	+	+	Hyperactive then absent bowel sounds Abdominal tenderness	+	+	–	Nl	–	↑	↓	↑	Elevated CRP Elevated ESR Elevated serum lactate Elevated lactate dehydrogenase (LDH)  Elevated creatine phosphokinase (CPK) Elevated amylase Hypoalbuminemia	IgA vasculitis	Hypercoagulability  Nonocclusive colonic ischemia Embolic and thrombotic arterial occlusion Mesenteric vein thrombosis	Abdominal CT scan
Tropical sprue		+	+	+	–	+	+	+	+	Angular stomatitis Oral mucosal lesion	+	–	–	Nl	Positive stool culture	Nl	↓	Nl	Fat soluble vitamins deficiency Vitamin B12 deficiency Folate deficiency Hypokalemia	Myalgia Neuropathy Edema	Escherichia coli Klebsiella pneumoniae Enterobacter cloacae	Diagnosis of exclusion
Cause		Duration		Diarrhea			Fever	Abdominal pain	Weight loss	GI signs	Stool exam					CBC			Other lab findings	Extra intestinal findings	Cause/Pathogenesis	Gold standard diagnosis
		Acute	Chronic	Watery	Bloody	Fatty					WBC	RBC	Ova/Parasite	Osmotic gap	Other	WBC	Hgb	Plt
Pseudomembranous enterocolitis		+	–	+	±	–	+	+	±	Generalized abdominal tenderness Abdominal distention Rebound abdominal tenderness	+	+	–	Nl	Enzyme–linked immunosorbent assay (ELISA) Polymerase chain reaction (PCR) assay or C. difficile antigen	↑	↓	↓	Elevated serum creatinine Hypoalbuminemia Elevated lactic acid	Dehydration Acute kidney injury Bacteremia Reactive arthritis Necrotizing fasciitis	Clostridium difficile Recent antibiotics use Recent surgery	Stool exam Pseudomembranes on colonoscopy
Escherichia coli enteritis	EPEC	+	+	+	+	–	+	+	+	Diffuse abdominal tenderness	+	+	–	Nl	Positive stool culture	↑	Nl	Nl	–	–	Enteropathogenic E. coli	DNA probe or polymerase chain reaction (PCR) of the EPEC adherence factor Stool culture
Food poisoning Staphylococcus aureus Bacillus cereus Clostridium perfringens		+	–	+	±	–	+	+	±	Abdominal distention	+	±	–	Nl	Positive stool culture	↑	Nl	Nl	–	History of travel or ingestion of infected food	Enterotoxins	Stool culture
Cause		Duration		Diarrhea			Fever	Abdominal pain	Weight loss	GI signs	Stool exam					CBC			Other lab findings	Extra intestinal findings	Cause/Pathogenesis	Gold standard diagnosis
		Acute	Chronic	Watery	Bloody	Fatty					WBC	RBC	Ova/Parasite	Osmotic gap	Other	WBC	Hgb	Plt
Isospora		+	+	+	–	+	+	+	+	Abdominal distention Diffuse abdominal tenderness	+	+	+	Nl	Positive stool microscopy Positive fecal fat	↑	Nl	Nl	Elevated eosinophils  Hypokalemia Increased creatinine	Chronic illness in immunocompromised patients	Isospora	Detecting oocysts in the feces
VIPoma		+	+	+	–	+	–	+	+	Abdominal distention Abdominal RUQ tenderness Nausea Vomiting	–	–	–	↓	–	Nl	Nl	Nl	Elevated VIP level Hypokalemia Hypochlorhydria or achlorhydria Low osmotic gap (<50 mOsm/kg)	Rash Facial flushing Dehydration Lethargy Muscle weakness	Primary secretory tumor	Blood VIP levels Followed by imaging
Medications ACE inhibitors Digoxin Cephalosporins Statins Thiazide diuretics Triptans Lactulose Anti retroviral agents Chemotherapeutic agents Antifungals Magnesium		+	+	+	–	±	±	+	+	Abdominal distention Dehydration	–	–	–	↑/↓	–	↑	Nl	Nl	Elevated plasma level of drug	–	Inflammation Pseudomembranous colitis	Clinical evaluation after discontinuation of the drugs
Cause		Duration		Diarrhea			Fever	Abdominal pain	Weight loss	GI signs	Stool exam					CBC			Other lab findings	Extra intestinal findings	Cause/Pathogenesis	Gold standard diagnosis
		Acute	Chronic	Watery	Bloody	Fatty					WBC	RBC	Ova/Parasite	Osmotic gap	Other	WBC	Hgb	Plt
Factitious diarrhea		+	+	+	–	–	–	+	+	Abdominal distention	–	–	–	↑/↓	–	Nl	Nl	Nl	Hypokalemia  Metabolic alkalosis Hypermagnesemia	Malabsorption Lethargy Generalized weakness Acute renal failure	Medications	Clinical evaluation after discontinuation of the drugs
Short bowel syndrome		+	+	+	–	+	–	–	+	Abdominal distention Abdominal tenderness	–	–	–	Nl	Positive fecal fat	Nl	↓	↑	Hypoalbuminemia High level of acute phase reactant Abnormal liver function tests	Prior intestinal surgery Malabsorption Crohn's disease Malignancy Peripheral edema Muscle atrophy	Surgical bowel resection	Clinical diagnosis following bowel resection
Radiation enteritis		+	+	+	+	+	–	+	+	Abdominal tenderness	+	+	–	Nl	Positive fecal fat	Nl	↓	Nl	Vitamin B12 deficiency Hypoalbuminemia	Prior history of malignancy and radiation therapy Malabsorption Telangiectasias	Radiation	Segmental bowel inflammation on endoscopy or colonoscopy