Sandbox: malabsorption

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

Cause	Peak age of onset	History					Physical exam	Lab findings				Additional findings	Cause/Pathogenesis	Gold standard diagnosis
		Fever	Abdominal pain	Diarrhea		Weight loss
				Watery	Fatty			WBC	Hgb	Plt	Other lab findings
Whipple's disease	40-60	+/-	+	+	+	+	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	Childhood Adult	-	+	+/-	+/-	+	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
Cystic fibrosis	Childhood	+	+	-	+	+	Digital clubbing Rales, wheeze, and crackle Cyanosis				Positive DNA analysis for CFTR multimutation method 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
Crohns disease	Young adults (20th)	+	+	+	+	+	Abdominal tenderness Tachycardia Hypotension	↑	↓		Iron deficiency Vitamin B12 deficiency Elevated erythrocyte sedimentation rate Elevated CRP	Blood seen on rectal exam	Abnormal immune response to self antigens	Colonoscopy with biopsy
Laxative overuse	After childhood	+	-		+/-	+/-	Enhanced gastrointestinal motility and gastrointestinal sound Mild abdominal tenderness Abdominal bloating				Hypokalemia  Metabolic alkalosis Hypermagnesemia(in case of magnesium laxative usage)	-	Laxative drug abuse	Laxative screening on a stool for: Diphenolic laxatives (eg, bisacodyl) Polyethylene glycol-containing laxatives
Hyperthyroidism	Any age	+	-		+	+/-	Lump in the neck Proptosis Tremors Increased DTR				Elevated T4 Elevated T3 Decreased level of TSH	Lid lag Sweating Hyperpigmentation	Graves' disease Hashimoto thyroiditis Toxic adenoma	TSH
Irritable bowel syndrome	Between 30 and 50	+	-		-	+	Abdominal tenderness Hard stool in the rectal vault				-	Bloating Flatulence	Postinfectious Inflammatory	Clinical diagnosis ROME III criteria Pharmacologic studies based criteria
VIPoma	Between 30 and 50	+	-		+	+/-	Tachycardia Rash Facial flushing Abdominal distention Abdominal tenderness in the right upper abdominal quadrant				Hypokalemia Hypochlorhydria or achlorhydria Low osmotic gap (<50 mOsm/kg)	Dehydration Lethargy, muscle weakness Nausea, vomiting Flushing	Primary secretory tumor	Elevated VIP levels Followed by imaging
Gastrinoma (Zollinger-Ellison syndrome)	Between the ages of 20 and 50	+	-		+	+	Mild to moderate upper abdominal tenderness				Positive secretin stimulation test Elevated serum chromogranin A	Heartburn	Gastrin producing tumor mainly in duodenum	Elevated basal or stimulated serum gastrin more than 1000 pg/mL
Lactose intolerance	Any age	-	+		+	+/-	Abdominal tenderness when palpated in severe disease Fever Hypotension Tachycardia Nausea and vomiting				Lactose breath hydrogen test	Bloating Flatulence Symptoms begin mainly after ingestion of lactose	Reduction of lactase enzyme activity or in ability to produce persistent lactase Congenital lactase deficiency	Lactase activity assay
Allergic enteropathy/Food protein-induced enterocolitis syndrome (FPIES)	Infancy	+	-		+/-	+	Nausea Vomiting Abdominal distention				Stool examination: Blood-tinged and mucusy Polymorphonuclear leukocytes presence	Triggered by cow milk protein Profuse, repetitive vomiting	Autoimmune/allergic response to food antigens	Oral food challenge (OFC)
Eosinophilic gastroenteritis	30th	+	-		+/-	+	Nausea Vomiting Abdominal distention				Elevated serum IgE levels Abnormal D-xylose test	One-half of patients have other allergic diseases Associated with an identifiable dietary antigen	Autoimmune/allergic response to food antigens	Eosinophilic infiltration of the gastrointestinal tract on biopsy
Primary bile acid malabsorption	Childhood Adolescents	+	+/-		+	+/-	-				Low vitamins A, D, E, and K Anemia	Disease hetergenicity lead to varying presentation from chronic diarrhea without significant fat malabsorption to severe watery diarrhea and steatorrhea with malnutrition	Genetic defects in SLC10A2 (solute carrier family 10 member 2 gene)	Total and specific bile acids from stool Gamma emitter selenium-75-homocholic acid taurine (SeHCAT)
Abetalipoproteinemia	Infancy	-	+		+	+	Abdominal distention Impaired visual acuity and visual field defects Dysarthria				Low triglyceride Low total cholesterol levels  Acanthocytes Low vitamin E levels	Clumsiness Vision 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	60th	+	-		+	+	Abdominal tenderness				Elevatedautoantibodies include: RF ANA AMA ANCA	Fecal urgency Incontinence May be associated with extraintestinal symptoms, such as: Arthralgia Arthritis Uveitis	Mucosal immune responses to luminal factors in a genetically predisposed individual	A 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
Grain allergy	Childhood	-	+	+	-	+	Vomiting Abdominal distension				Elevated IgE	Atopic dermatitis Dysphagia	Abnormal immune response to wheat antigens	Measurement of grain-specific immunoglobulin E (IgE)