Differentiating Lactose intolerance from other diseases

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

Overview

Lactose intolerance must be differentiated from other diseases that cause diarrhea such as pancreatic insufficiency, irritable bowel syndrome, small intestinal bacterial overgrowth, celiac disease, and inflammatory bowel disease

Differentiating lactose intolerance from other Diseases

• Lactose intolerance must be differentiated from other diseases that cause diarrhea such as pancreatic insufficiency, irritable bowel syndrome, small intestinal bacterial overgrowth, celiac disease, and inflammatory bowel disease
• Lactose intolerance must be differentiated from other causes that produce bloating and flatulence such as beans that contain stachyose and raffinose, two indigestible sugars.

References

Template:WH Template:WS The table below summarizes the findings that differentiate watery causes of chronic diarrhea

Cause			Osmotic gap		History	Physical exam	Gold standard	Treatment
			< 50 mOsm per kg	> 50 mOsm per kg*
Watery	Secretory	Crohns	+	-	Abdominal pain followed by diarrhea	Abdominal tenderness when palpated in severe disease Blood seen on rectal exam Fever Tachycardia Hypotension	Colonoscopy with biopsy	Topical mucosamine and corticosteroids are preferred Mesalamine and sulfasalazine are used for remission
		Hyperthyroidism	+	-	Excessive sweating Heat intolerance Increased bowel movements	Lump in the neck Proptosis Tremors Increased DTR	TSH with T3 and T4	Carbimazole and methimazole Beta blockers like propylthiouracil Iodine-131
		VIPoma	+	-	Watery diarrhea Dehydration (thirst, dry skin, dry mouth, tiredness, headaches, and dizziness) Lethargy, muscle weakness Nausea, vomiting Crampy abdominal pain Weight loss Flushing	Tachycardia Rash Facial flushing Abdominal distention Abdominal tenderness in the right upper abdominal quadrant	Elevated VIP levels Followed by imaging	Sandostatin or chemotherapy for malignant tumors Surgical removal of the tumor
	Osmotic	Lactose intolerance	-	+	Abdominal pain Bloating Diarrhea Flatulence	Abdominal tenderness	Intestinal biopsy	Avoidance of dietary lactose Substitution to maintain nutrient intake Regulation of calcium intake Use of enzyme lactase
		Celiac disease	-	+	May be asymptomatic Vague abdominal pain Diarrhea Weight loss Malabsorption / steatorrhea Bloatedness	Abdominal pain and cramping Abdominal distention Tetany Mouth ulcers Dermatitis herpetiformis Signs of the fat-soluble vitamins A, D, E, and K deficiency	IgA tissue transglutaminase Ab	Gluten-free diet
	Functional	Irritable bowel syndrome	-	-	Abdominal pain or discomfort recurring at least 3 days per month in the past 3 months and associated with 2 or more of the following: Improves with defecation Onset associated with change in frequency of stool Onset associated with change in appearance of stool 25% of bowel movements are loose stools History of straining is also common	Abdominal tenderness Hard stool in the rectal vault	Clinical diagnosis ROME III criteria Pharmacologic studies based criteria	High dietary fiber Osmotic laxatives such as polyethylene glycol, sorbitol, and lactulose Antispasmodic drugs (e.g. anticholinergics such as hyoscyamine or dicyclomine)

The table below summarizes the findings that differentiate fatty causes of chronic diarrhea

Cause	Osmotic gap		History	Physical exam	Gold standard	Treatment
	< 50 mOsm per kg	> 50 mOsm per kg*
lactose intolerance	-	+	Bloating, Flatulence Abdominal pain, and/or chronic diarrhea after ingestion of lactose	Abdominal tenderness when palpated in severe disease Fever Hypotension Tachycardia Nausea and vomiting	Lactose breath hydrogen test	Restriction of lactose and maintain calcium and vitamin D intake.
Celiac sprue	-	+	Diarrhea with bulky, foul-smelling stools Growth failure in children, Weight loss, Anemia, Neurologic disorders Osteopenia	Neuropsychiatric disease Dermatitis herpetiformis Arthritis Iron deficiency Metabolic bone disease Hyposplenism Kidney disease Idiopathic pulmonary hemosiderosis	Immunoglobulin A (IgA) anti-tissue transglutaminase (TTG) antibody followed by upper endoscopy with biopsy.	Dietary counseling, elimination of gluten in the diet.
Whipple disease	-	+	Arthralgias Weight loss Diarrhea Abdominal pain	Leukocytopenia Thrombocytopenia Skin hyperpigmentation	Upper endoscopy with biopsies of the small intestine for T. whipplei testing (histology with PAS staining, polymerase chain reaction [[[PCR]]] testing, and immunohistochemistry)	Doxycycline and hydroxychloroquine are bactericidal

Lactose intolerance must be differentiated from diseases that cause abdominal pain and chronic diarrhea. The table below summarizes the findings that differentiate watery causes of chronic diarrhea:

Cause	Osmotic gap		History	Physical exam	Gold standard for diagnosis
	< 50 mOsm per kg	> 50 mOsm per kg*
Zollinger-Ellison syndrome	+	-	Abdominal pain and diarrhea Dyspepsia Upper or Lower gastrointestinal bleeding	Abdominal tenderness Hematochezia Hematemesis Tachycardia Hypotension	Gastrin levels
Crohn's disease	+	-	Abdominal pain followed by diarrhea	Abdominal tenderness when palpated in severe disease Blood seen on rectal exam Fever Tachycardia Hypotension	Colonoscopy with biopsy
Hyperthyroidism	+	-	Excessive sweating Heat intolerance Increased bowel movements	Lump in the neck Proptosis Tremors Increased DTR	TSH with T3 and T4
VIPoma	+	-	Watery diarrhea Dehydration (thirst, dry skin, dry mouth, tiredness, headaches, and dizziness) Lethargy, muscle weakness Nausea, vomiting Cramping abdominal pain Weight loss Flushing	Tachycardia Rash Facial flushing Abdominal distention Abdominal tenderness in the right upper abdominal quadrant	Elevated VIP levels Followed by imaging
Lactose intolerance	-	+	Abdominal pain Bloating Diarrhea Flatulence	Abdominal tenderness	Intestinal biopsy
Celiac disease	-	+	May be asymptomatic Vague abdominal pain Diarrhea Weight loss Malabsorption/steatorrhea Bloatedness	Abdominal pain and cramping Abdominal distention Tetany Mouth ulcers Dermatitis herpetiformis Signs of the fat-soluble vitamins A, D, E, and K deficiency	IgA tissue transglutaminase Ab
Irritable bowel syndrome	-	-	Abdominal pain or discomfort recurring at least 3 days per month in the past 3 months and associated with 2 or more of the following: Improves with defecation Onset associated with change in frequency of stool Onset associated with change in appearance of stool 25% of bowel movements are loose stools History of straining is also common.	Abdominal tenderness Hard stool in the rectal vault	Clinical diagnosis ROME III criteria Pharmacologic studies based criteria