Sandbox: malabsorption

Abbreviations: WBC: White blood cells; Plt: Platelets, Hgb: Hemoglobin, IgE: Immunoglobulin E, IgA: Immunoglobulin A

	Cause	Clinical manifestation							Lab findings				Additional findings	Cause/Pathogenesis	Gold standard diagnosis
		Symptoms						Signs
		Diarrhea			Fever	Abdominal pain	Weight loss
		Watery	Bloody	Fatty					WBC	Hgb	Plt	Other lab findings
	Whipple's disease	+	-	+	±	+	+	Abnormal extraocular movement Lymphadenopathy Hyperpigmentation Decreased breathing sound	↓	↓	↓/↑	Hypoalbuminemia	Uveitis Endocarditis Encephalitis Dementia Hepatosplenomegaly Ascites Pleural effusion	Tropheryma whipplei HLA-B27	Small intestine biopsy for Tropheryma whipplei testing PCR testing
	Celiac disease	±	-	±	-	+	+	Abdominal distention Tetany Mouth ulcers	-	↓	-	IgA endomysial antibody Anti-tissue transglutaminase antibody Anti-gliadin antibody	Signs of the fat-soluble vitamins A, D, E, and K deficiency Dementia Hepatosplenomegaly Ascites Dermatitis herpetiformis Must follow Gluten-free diet	HLA-DQ2 HLA-DQ8 Innate responses to wheat proteins	IgA endomysial antibody IgA tissue transglutaminase antibody
	Tropical sprue	+	-	+	+	+	+	Pallor Angular stomatitis Mouth ulcers Edema	-	↓	-	Low vitamin B12 Low folic acid Hypokalemia		Unknown Bacteria including Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae	Diagnosis of exclusion
	Crohns disease	+	+	+	+	+	+	Abdominal tenderness Tachycardia Hypotension	↑	↓	↑	Iron deficiency Vitamin B12 deficiency Elevated ESR Elevated CRP	Blood seen on rectal exam	Abnormal immune response to self antigens	Colonoscopy with biopsy
	Ulcerative colitis	+	+	+	+	+	+	Abdominal tenderness Tachycardia Hypotension Skin rash Aphthous ulcers Clubbing of the fingers	↑	↓	↑	Hypoalbuminemia Hypokalemia Hypomagnesemia Iron deficiency Elevated ESR Elevated CRP	Iritis Uveitis Seronegative arthritis Erythema nodosum	Abnormal immune response to self antigens	Colonoscopy with biopsy
	Cystic fibrosis	-	-	+	±	+	+	Digital clubbing Abnormal breathing sounds Cyanosis	-	↓	-	Positive DNA analysis for CFTR Evaluated nasal transepithelial potential difference (NPD)	Diabetes Recurrent upper and lower respiratory tract infections Infertility	Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein	Elevated sweat chloride ≥60 mmol/L
	VIPoma	+	-	+	-	+	+	Tachycardia Rash Facial flushing Abdominal distention Abdominal RUQ tenderness	-	-	-	Elevated VIP level Hypokalemia Hypochlorhydria or achlorhydria Low osmotic gap (<50 mOsm/kg)	Dehydration Lethargy Muscle weakness Nausea Vomiting	Primary secretory tumor	Elevated VIP levels Followed by imaging
	Zollinger-Ellison syndrome	+	-	+	-	+	+	Abdominal tenderness	-	↓	-	Positive secretin stimulation test Elevated serum chromogranin A	Heartburn	Gastrin producing tumor mainly in duodenum	Elevated basal or stimulated serum gastrin> 120 pg/mL
	Eosinophilic gastroenteritis	+	-	+	-	+	+	Abdominal distention	↑	-	-	Elevated serum IgE levels Eosinophilia Elevated ESR Hypoalbuminemia	Other allergic disorders Associated with an identifiable dietary antigen	Autoimmune allergic response to food antigens	Eosinophilic infiltration of the gastrointestinal tract on biopsy
	Primary bile acid malabsorption	+	-	+	-	+	+		-	↓	-	Low vitamins A, D, E, and K		Genetic defects in SLC10A2 (solute carrier family 10 member 2 gene)	Elevated total and specific bile acids in stool Positive SeHCAT
	Abetalipoproteinemia	+	-	+	-	+	+	Abdominal distension Visual field defect Dysarthria	-	-	-	Low triglyceride Low total cholesterol levels  Acanthocytes Low vitamin E levels	Visual impairment Ataxia	Autosomal recessive disorder caused by mutations encoding the microsomal triglyceride transfer protein (MTP)	Clinical findings and low triglyceride and cholesterol level
	Microscopic colitis	+	+	-	-	+	+	Abdominal tenderness	-	↓	-	Elevated autoantibodies include: RF ANA AMA ANCA	Fecal urgency Fecal incontinence Arthralgia Arthritis Uveitis	Mucosal immune responses to luminal factors in a genetically predisposed individual	Colonoscopy with mucosal biopsy with mononuclear infiltrates: Collagenous colitis is characterized by a colonic subepithelial collagen band >10 micrometers in diameter Lymphocytic colitis is characterized by ≥20 intraepithelial lymphocytes (IEL) per 100 surface epithelial cells
	Hyperthyroidism	+	-	-	±	+	+	Lump in the neck Proptosis Tremor Increased DTR	-	-	-	Elevated T4 Elevated T3 Decreased TSH	Lid lag Sweating Hyperpigmentation	Graves' disease Hashimoto's thyroiditis Toxic adenoma	TSH
	Lactose intolerance	+	-	-	-	+	-	Abdominal tenderness Hypotension Tachycardia Nausea and vomiting	-	-	-	Hydrogen breath test	Bloating Flatulence Symptoms begin mainly after ingestion of lactose	Reduction of lactase enzyme activity or inability to produce persistent lactase Congenital lactase deficiency	Lactase activity assay
	Irritable bowel syndrome	±	-	±	-	±	-	Abdominal tenderness Flatulence Hard stool in the rectal vault	-	-	-				Diagnosis of exclusion
	Chronic pancreatitis	+	-	+	-	+	+								Secretin stimulation test
	Cirrhosis	+	-	+	+	+	+
	Short bowel syndrome		-
	Intestinal lymphoma
	Agammaglobulinemia
	Intestinal lymphangiectasia
	Amyloidosis
	Mastocytosis
	Small intestinal bacterial overgrowth
	Drug induced enteritis
Infection	HIV infection
	Giardiasis
	Strongyloidiasis
	Tuberculosis