Diagnostic Tests for Diarrhea

Diagnostic Test list for Diarrhea:

The list of diagnostic tests mentioned in various sources as used in the diagnosis of Diarrhea includes:

• Physical examination
  • Abdominal examination for tenderness and a mass e.g. a mass in the right lower abdomen may suggest bowel cancer or diverticulitis; a mass on right, left or upper abdomen may also suggest bowel cancer; tenderness in the left lower abdomen, with or without a significant mass may suggest ulcerative colitis, diverticulitis or irritable bowel syndrome
  • Examine rectum for hemorrhoids and anal fissure that may be causing a positive occult blood test
  • Examine for signs of systemic diseases that may cause diarrhea e.g. tremor and increased heart rate of hyperthyroidism; considerable flushing of carcinoid syndrome; hyperpigmentation of the skin in Addison's disease; and dermatitis and dementia of pellagra
• Blood tests
  • Full blood count and ESR, Electrolytes and thyroid function tests - if systemic disease is suspected to be the cause of diarrhea.
  • Salmonella antibodies - not useful in acute situation.
  • Amoeba antibodies - not useful in acute situation.
  • HIV test - if suspected on history.
  • Gastrin level - if suspect a gastrinoma (Zollinger-Ellison syndrome).
• Stool tests
  • Test for occult blood (if positive may suggest infectious disease of the large intestine or small intestine, ulcerative colitis, bowel cancer, diverticulitis, Zollinger-Ellison syndrome)
  • Stool microscopy for ova, parasites and culture for bacteria
  • Giardia antigen
  • Clostridium difficile toxin B - if history of antibiotic use.
  • 24 hour Stool analysis of fecal fat - if steatorrhea is present (i.e. fatty, pale colored, extremely smelly stools that float in the toilet and are difficult to flush away due to excess fat in the stool).
• Urine tests
  • 5-HIAA - if suspect Carcinoid syndrome.
• Radiological investigations
  • Barium enema
• Sigmoidoscopy and/or colonoscopy with or without a small bowel aspiration and biopsy - if diarrhea persists or if blood is present ( may be required to detect bowel cancer, bowel polyps, celiac disease, Giardia infection.

Home Diagnostic Testing

These home medical tests may be relevant to Diarrhea causes:

• Colon & Rectal Cancer: Home Testing
  • Home Colorectal Cancer Tests
  • Home Fecal Occult Bleeding Tests
• Food Allergies & Intolerances: Home Testing:
  • Home Food Allergy Tests
  • Home Food Intolerance Testing
  • Home Water Testing
  • Home Lead Poisoning Tests
  • Home Heavy Metal Poisoning Tests
• Digestive-Related Home Testing:
  • Home Stomach Ulcer Tests
  • Home Colorectal Cancer Test Kits
  • Home Fecal Occult Bleeding Test Kits

Tests and diagnosis discussion for Diarrhea:

Diagnostic tests to find the cause of diarrhea include the following:

• Medical history and physical examination. The doctor will need to know about your eating habits and medication use and will examine you for signs of illness.

• Stool culture. Lab technicians analyze a sample of stool to check for bacteria, parasites, or other signs of disease or infection.

• Blood tests. Blood tests can be helpful in ruling out certain diseases.

• Fasting tests. To find out if a food intolerance or allergy is causing the diarrhea, the doctor may ask you to avoid lactose (found in milk products), carbohydrates, wheat, or other foods to see whether the diarrhea responds to a change in diet.

• Sigmoidoscopy. For this test, the doctor uses a special instrument to look at the inside of the rectum and lower part of the colon.

• Colonoscopy. This test is similar to sigmoidoscopy, but the doctor looks at the entire colon.