Tropical sprue differential diagnosis

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

Overview

Tropical sprue should be differentiated from diseases causing chronic diarrhea and malabsorption such as celiac disease, osmotic diarrhea and secretory diarrhea.

Differentiating Tropical Sprue from other Diseases

Tropical sprue is a diagnosis of exclusion therefore it must be be differentiated from other diseases causing malabsorption such as:

• Infectious causes
• Celiac disease
• Pancreatic insufficiency
• Osmotic diarrhea
• Secretory diarrhea

Approach to a Patient with Chronic Diarrhea

The following is an algorithm describing the approch to a patient with chronic diarrhea:

Classify diarrhea by the results of the stool analysis

Stool osmotic gap >50 mOsm/kg

Stool osmotic gap <50 mOsm/kg

Fecal occult blood (+), WBC (+), lactoferrin (+), calprotectin(+)

Fecal fat (+)

Osmotic diarrhea

Secretory diarrhea

Inflammatory diarrhea

Fatty diarrhea

• Check the pH of the stool

Low pH • Evaluate for carbohydrate malabsorption

High pH • Evaluate for ingestion of magnesium or antacids • Evaluate for laxative abuse

1. Exclude infection by any/combination of the following tests: • Stool culture • Microscopic evaluation for ova and parasites • Stool antigen test for Giardia • Small bowel aspirate or breath H2 test to rule out bacterial overgrowth

1. Exclude structural disease by any/combination of the following tests: • Small bowel radiographs • Sigmoidoscopy or colonoscopy with biopsy • CT abdomen • UGI scopy and small bowel biopsy

1. Exclude structural disease by any/combination of the following tests • Small bowel radiographs • CT abdomen • Small bowel biopsy and aspirate for quantitative culture

• Take a careful dietary history • Order breath H2 test (lactose), OR • Order lactase measurement in a mucosal biopsy

• Order stool alkanization test • Order chromatographic and chemical tests

2. Exclude structural disease by any/combination of the following tests: • Small bowel radiographs • Sigmoidoscopy or colonoscopy with biopsy • CT abdomen • Biopsy of the proximal small bowel mucosa

2. Exclude infection by any/combination of the following tests: • Stool culture: Standard Aeromonas, Plesiomonas, Tuberculosis etc • Stool for ova and parasites • Clostridium toxin assay • Other specific test (Serology, ELISA, immunofluorescence to rule out virus and parasites)

2. Exclude exocrine pancreatic insufficieny by any/combination of the following tests: • Secretin test • Stool chymotrypsin activity • Bentiromide test • Others (D-xylose absorption tests / Schilling test)

3. Order selective testing: • Cholestyramine test for bile acid diarrhea • Plasma peptides (Gastrin, calcitonin, vasoactive intestinal polypeptide or somatostatin) • Urine (5-hydroxyindole acetic acid, metanephrine or histamine) • Others (TSH, ACTH stimulation test, serum protein electrophoresis or serum immunoglobulins)

Confirmatory diagnosis

Yes

Specific treatment per results and symptomatic treatment

Suspect Tropical sprue and initiate antibiotic therapy and folate supplementation

Tropical sprue must be differentiated from other diseases that may cause chronic diarrhea, weight loss, and abdominal pain especially in immunocompromised patients.

Disease	Prominent clinical findings	Laboratory or radiological findings
Chronic giardiasis	Chronic giardiasis may develop after acute episode of giardiasis or without any acute events. Loose foul smelling stools Flatulence Fatigue Weight loss Steatorrhea Some patients develop acquired lactose intolerance (manifested by exacerbation of symptoms following ingestion of dairy products)	Microscopic identification of the organism in the stool Hypoalbuminaemia Vitamin B12 and folate deficiencies (as the organism inhabits the duodenum)
Cryptosporidiosis	Incubation period is 7-10 days. In immunocompetent patients: Disease might be asymptomatic or cause gastroenteritis (but without any biliary involvement) Gastroenteritis usually resolves spontaneously within 14 days. In immunocompromised patients: Disease is usually more severe and prolonged (especially in severly immunocomprmised patients with CD4 count < 100 cells/microL). Cryptosporidiosis may involve the biliary tract and the liver. Weight loss Abdominal RUQ tenderness might be present if biliary or hepatic involvement is present.	Microscopic identification of the organism in the stool: The oocysts appear red on staining with modified acid fast staining PCR: Most specific and sensitive diagnostic tool. PCR is expensive and used in limited cases.
Cystoisosporiasis (isosporiasis)	Cystoisosporiasis is usually seen in immunocompromised patients. Incubation period can last up to 2 weeks Watery diarrhea that is profuse and foul smelling Constitutional symptoms (headache, low grade fever, myalgia and malaise)	Isospora ova or parasites can be visualized on stool microscopic examination. Upper GI endoscopy may used for excluding other esophageal or gastric disease and obtaining specimens for histopathology.
Tropical sprue	History of travel to a tropical region (for a period more than a month) Chronic diarrhea Steatorrhea Examination may show signs of vitamin deficiencies (eg glossitis)	Megaloblastic anemia that might progress into pancytopenia Hypoalbuminaemia Vitamin D defeciency and hypocalcemia

Abbreviations: RUQ= Right upper quadrant of the abdomen, LUQ= Left upper quadrant, LLQ= Left lower quadrant, RLQ= Right lower quadrant, LFT= Liver function test, SIRS= Systemic inflammatory response syndrome, ERCP= Endoscopic retrograde cholangiopancreatography, IV= Intravenous, N= Normal, AMA= Anti mitochondrial antibodies, LDH= Lactate dehydrogenase, GI= Gastrointestinal, CXR= Chest X ray, IgA= Immunoglobulin A, IgG= Immunoglobulin G, IgM= Immunoglobulin M, CT= Computed tomography, PMN= Polymorphonuclear cells, ESR= Erythrocyte sedimentation rate, CRP= C-reactive protein, TS= Transferrin saturation, SF= Serum Ferritin, SMA= Superior mesenteric artery, SMV= Superior mesenteric vein, ECG= Electrocardiogram, US = Ultrasound

Classification of pain in the abdomen based on etiology Disease Clinical manifestations Diagnosis Comments Symptoms Signs Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Abdominal causes Inflammatory causes Pancreato-biliary disorders Acute suppurative cholangitis RUQ + + + + − − − − + + + N Abnormal LFT WBC >10,000 Ultrasound shows biliary dilatation/stents/tumor Septic shock occurs with features of SIRS Acute cholangitis RUQ + − − + − − − − − − − N Abnormal LFT Ultrasound shows biliary dilatation/stents/tumor Biliary drainage (ERCP) + IV antibiotics Acute cholecystitis RUQ + − + + − − − − − − − Hypoactive Hyperbilirubinemia Leukocytosis Ultrasound shows: Gallstone Inflammation Murphy’s sign Acute pancreatitis Epigastric + − + ± − − + − ± − − N Increased amylase / lipase Ultrasound shows evidence of inflammation CT scan shows severity of pancreatitis Pain radiation to back Chronic pancreatitis Epigastric − − ± ± − + + − − − − N Increased amylase / lipase Increased stool fat content Pancreatic function test CT scan Calcification Pseudocyst Dilation of main pancreatic duct Predisposes to pancreatic cancer Pancreatic carcinoma Epigastric − − + + − + + − − − − N ↑ Alkaline phosphatase ↑ serum bilirubin ↑ gamma-glutamyl transpeptidase ↑ CA 19-9  MDCT with  PET/CT MRI Skin manifestations may include: Bullous pemphigoid Cicatricial pemphigoid Migratory superficial thrombophlebitis (classic Trousseau's syndrome) Pancreatic panniculitis Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Primary biliary cirrhosis RUQ/Epigastric − − − + − − − − − − − N Increased AMA level, abnormal LFTs ERCP Pruritis Primary sclerosing cholangitis RUQ + − − + − − − − − − − N Increased liver enzymes Increased IgM, IgG4 Anti-neutrophil cytoplasmic antibody (p-ANCA) Anti-nuclear antibody (ANA) Anti-smooth muscle antibody (Anti-Sm) Anti-endothelial antibody Anti-cardiolipin antibody ERCP and MRCP shows Multiple segmental strictures Mural irregularities Biliary dilatation and diverticula Distortion of biliary tree The risk of cholangiocarcinoma in patients with primary sclerosing cholangitis is 400 times higher than the risk in the general population. Cholelithiasis RUQ/Epigastric ± − ± ± − − − − − − − Normal to hyperactive for dislodged stone Leukocytosis Ultrasound shows gallstone Fatty food intolerance Gastric causes Peptic ulcer disease Diffuse ± − + − − − + Gastric ulcer- melena and hematemesis Duodenal ulcer- melena and hematochezia Positive if perforated Positive if perforated Positive if perforated N Ascitic fluid LDH > serum LDH Glucose < 50mg/dl Total protein > 1g/dl Air under diaphragm in upright CXR Upper GI endoscopy for diagnosis Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Gastritis Epigastric ± − + − − − Positive in chronic gastritis + − − − N H.pylori infection diagnostic tests Endoscopy H.pylori gastritis guideline recommendation Gastroesophageal reflux disease Epigastric − − ± − − − − − − − − N N Gastric emptying studies Esophageal manometry Endoscopy for alarm signs Gastric outlet obstruction Epigastric − − ± − − − + − − − − Hyperactive Complete blood count Basic metabolic panel Abdominal x-ray- air fluid level Barium upper GI studies- narrowed pylorus Succussion splash Gastroparesis Epigastric − − + − − − + − ± − − Hyperactive/hypoactive Hemoglobin Fasting plasma glucose Serum total protein, albumin, thyrotropin (TSH), and an antinuclear antibody (ANA) titer HbA1c Scintigraphic gastric emptying Succussion splash Single photon emission computed tomography (SPECT) Full thickness gastric and small intestinal biopsy Gastrointestinal perforation Diffuse + ± - ± − − − + + + ± Hyperactive/hypoactive WBC> 10,000 Air under diaphragm in upright CXR Hamman's sign Dumping syndrome Lower and then diffuse − − + − − + + − + − − Hyperactive Glucose challenge test Hydrogen breath test Upper GI series Gastric emptying study Postgastrectomy Intestinal causes Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Acute appendicitis Starts in epigastrium, migrates to RLQ + Positive in pyogenic appendicitis + − − ± − − Positive in perforated appendicitis + + Hypoactive Leukocytosis Ct scan Ultrasound Positive Rovsing sign Positive Obturator sign Positive Iliopsoas sign Acute diverticulitis LLQ + ± + − + ± − + Positive in perforated diverticulitis + + Hypoactive Leukocytosis CT scan Ultrasound History of constipation Inflammatory bowel disease Diffuse ± − − ± − + + + − − − Normal or hyperactive Anti-neutrophil cytoplasmic antibody (P-ANCA) in Ulcerative colitis Anti saccharomyces cerevisiae antibodies (ASCA) in Crohn's disease String sign on abdominal x-ray in Crohn's disease Extra intestinal findings: Uveitis Arthritis Irritable bowel syndrome Diffuse − − − − ± ± + − − − − N Normal Normal Symptomatic treatment High dietary fiber Osmotic laxatives Antispasmodic drugs Whipple's disease Diffuse ± − − ± − + + − ± − − N Thrombocytopenia Hypoalbuminemia Small intestinal biopsy for Tropheryma whipplei Endoscopy is used to confirm diagnosis. Images used to find complications Chest and joint x-ray CT MRI Echocardiography Extra intestinal findings: Uveitis Endocarditis Encephalitis Dementia Hepatosplenomegaly Arthritis Ascites Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Toxic megacolon Diffuse + − − − − + − − + ± + Hypoactive Anemia Leukocytosis especially in patients with Clostridium difficile infection Hypoalbuminemia Metabolic alkalosis associated with a poor prognosis Metabolic acidosis secondary to ischemic colitis CT and Ultrasound shows: Loss of colonic haustration Hypoechoic and thickened bowel walls with irregular internal margins in the sigmoid and descending colon Prominent dilation of the transverse colon (>6 cm) Insignificant dilation of ileal bowel loops (diameter >18 mm) with increased intraluminal gas and fluid Tropical sprue Diffuse + − − − − + + − − − − N Fat soluble vitamin deficiency Hypoalbuminemia Fecal stool test Barium studies: Dilation and edema of mucosal folds Steatorrhea- 10-40 g/day (Normal=5 g/day) Celiac disease Diffuse − − − − − + + − − − − Hyperactive IgA endomysial antibody IgA tissue transglutaminase antibody Anti-gliadin antibody Small bowel biopsy US: Bull’s eye or target pattern Pseudokidney sign Gluten allergy Infective colitis Diffuse + − ± − − + − + Positive in fulminant colitis ± ± Hyperactive Stool culture and studies Shiga toxin in bloody diarrhea PCR CT scan Bowel wall thickening Edema Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Colon carcinoma Diffuse/ RLQ/LLQ − − − − ± ± + + ± − − Normal or hyperactive if obstruction present CBC Carcinoembryonic antigen (CEA) Colonoscopy Flexible sigmoidoscopy Barium enema CT colonography  PILLCAM 2: A colon capsule for CRC screening may be used in patients with an incomplete colonoscopy who lacks obstruction Hepatic causes Viral hepatitis RUQ + − + + − Positive in Hep A and E + − Positive in fulminant hepatitis Positive in acute + N Abnormal LFTs Viral serology US Hep A and E have fecal-oral route of transmission Hep B and C transmits via blood transfusion and sexual contact. Liver abscess RUQ + + + + − ± + − + + ± Normal or hypoactive CBC Blood cultures Abnormal liver function tests US CT Hepatocellular carcinoma/Metastasis RUQ + − − + − − + − − − − Normal Hyperactive if obstruction present High levels of AFP in serum Abnormal liver function tests US CT Liver biopsy Other symptoms: Splenomegaly Variceal bleeding Ascites Spider nevi Asterixis Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Budd-Chiari syndrome RUQ ± − − ± − − − Positive in liver failure leading to varices − − − N Elevated serum aspartate aminotransferase and alanine aminotransferase levels may be more than five times the upper limit of the normal range. Elevated serum alkaline phosphatase and bilirubin levels, decreased serum albumin level. Findings on CT scan suggestive of Budd-Chiari syndrome include: Early enhancement of the caudate lobe and central liver around the inferior vena cava Delayed enhancement of the peripheral liver with accompanying central low density (flip-flop appearance) Peripheral zones of the liver show reversed portal venous blood flow In the chronic phase, there is caudate lobe enlargement and atrophy of the peripheral liver in affected areas Ascitic fluid examination shows: Total protein more than 2.5 g per deciliter White blood cells are usually less than 500/μL. Hemochromatosis RUQ − − − − − − − Positive in cirrhotic patients − − − N >60% TS >240 μg/L SF Raised LFT Hyperglycemia Ultrasound shows evidence of cirrhosis Extra intestinal findings: Hyperpigmentation Diabetes mellitus Arthralgia Impotence in males Cardiomyopathy Atherosclerosis Hypopituitarism Hypothyroidism Extrahepatic cancer Prone to specific infections Cirrhosis RUQ − − − + − − + + + − − N Hypoalbuminemia Prolonged PT Abnormal LFTs Hyponatremia Thrombocytopenia US Nodular, shrunken liver Ascites Stigmata of liver disease Cruveilhier- Baumgarten murmur Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Peritoneal causes Spontaneous bacterial peritonitis Diffuse + − − Positive in cirrhotic patients − + − − ± + + Hypoactive Ascitic fluid PMN>250 cells/mm³ Culture: Positive for single organism Ultrasound for evaluation of liver cirrhosis Renal causes Pyelonephritis Unilateral + ± + − − − − − + − − Hypoactive Urinalysis Urine culture Blood culture CT MRI CVA tenderness Renal colic Flank pain − − + − − − − − − − − N Hematuria Ultrasound CT scan Colicky abdominal pain Dysuria Hollow Viscous Obstruction Small bowel obstruction Diffuse + − + − + − + − + + ± Hyperactive then absent Leukocytosis with left shift indicates complications Abdominal X ray Dilated loops of bowel with air fluid levels Gasless abdomen "Target sign"– , indicative of intussusception Venous cut-off sign" – suggests thrombosis Volvulus Diffuse - − + − + − − − Positive in perforated cases + + Hyperactive then absent Leukocytosis CT scan and abdominal X ray U shaped sigmoid colon "Whirl sign" Biliary colic RUQ − − + + − − − − − − − N ↑ bilirubin and alkaline phosphatase Ultrasound Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Vascular Disorders Ischemic causes Mesenteric ischemia Periumbilical Positive if bowel becomes gangrenous − + − − + + + Positive if bowel becomes gangrenous Positive if bowel becomes gangrenous − Hyperactive to absent Leukocytosis and lactic acidosis Amylase levels D-dimer CT angiography SMA or SMV thrombosis Also known as abdominal angina that worsens with eating Acute ischemic colitis Diffuse + ± + − − + + + + + + Hyperactive then absent Leukocytosis Abdominal x-ray Distension and pneumatosis CT scan Double halo appearance, thumbprinting Thickening of bowel May lead to shock Hemorrhagic causes Ruptured abdominal aortic aneurysm Diffuse ± − + − − − + + + − − N Fibrinogen D-dimer Focused Assessment with Sonography in Trauma (FAST)  Unstable hemodynamics Intra-abdominal or retroperitoneal hemorrhage Diffuse ± − ± − − − − + + − − N ↓ Hb ↓ Hct CT scan History of trauma Disease Abdominal Pain Fever Rigors and chills Nausea or vomiting Jaundice Constipation Diarrhea Weight loss GI bleeding Hypo- tension Guarding Rebound Tenderness Bowel sounds Lab Findings Imaging Comments Gynaecological Causes Tubal causes Torsion of the cyst/ovary RLQ / LLQ − − + − − − − − − ± ± N ↑ ESR ↑ CRP Ultrasound Sudden onset & severe pain Acute salpingitis RLQ / LLQ + ± − − − − − − − ± ± N Leukocytosis Pelvic ultrasound Vaginal discharge Cyst rupture RLQ / LLQ − − + − − − − − + ± ± N ↑ ESR ↑ CRP Ultrasound Pregnancy Ruptured ectopic pregnancy RLQ / LLQ − − + − − − − − + + + N Positive pregnancy test Ultrasound History of Missed period Vaginal bleeding Extra-abdominal causes Pulmonary disorders Pleural empyema RUQ/Epigastric + ± − − − − + − − − − N Thoracentesis Chest X-ray Pleural opacity Localization of effusion Physical examination Crackles Egophony Increased tactile fremitus Pulmonary embolism RUQ/LUQ ± − − − − − − − ± − − N ABGs D-dimer CXR V/Q scan Spiral CT pulmonary angiogram Dyspnea Tachycardia Pleuretic chest pain Pneumonia RUQ/LUQ + + + − − ± − − + − − Normal or hypoactive ABGs Leukocytosis Pancytopenia CXR CT chest Bronchoscopy Shortness of breath Cough Cardiovascular disorders Myocardial Infarction Epigastric ± − + − − − − − Positive in cardiogenic shock − − N Cardiac enzymes ECG Echocardiogram Wall motion abnormality Wall rupture Septal rupture Chest pain, tightness, diaphoresis Complications: Arrythmias Mitral regurgitation Ventricular wall rupture Septal rupture