Lecture
Patient will present as → a 27-year-old female who has been experiencing postprandial bloating, flatulence, diarrhea, and abdominal pain for one year. Symptoms occur following the ingestion of milk products
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Lactose intolerant individuals have insufficient levels of lactase, an enzyme that catalyzes the hydrolysis of lactose into glucose and galactose, in their digestive system.
- In most cases, this causes symptoms that may include abdominal bloating and cramps, flatulence, diarrhea, nausea, borborygmi (rumbling stomach), or vomiting after consuming significant amounts of lactose
- Clinical symptoms typically appear within 30 minutes but may take up to two hours, depending on other foods and activities
- Patients may need calcium supplementation
The diagnosis of lactose intolerance should be considered in patients with bloating, flatulence, abdominal pain, and/or chronic diarrhea
- A presumptive diagnosis of lactose intolerance can be made in patients with mild symptoms that occur with significant lactose ingestion (eg, >2 servings of dairy/day or >1 serving in a single dose that is not associated with a meal) and resolve after five to seven days of avoidance of lactose-containing foods, with recurrence on rechallenge
Definitive diagnosis is with lactose breath hydrogen test
- The patient drinks a liquid that has lactose in it. Then they breathe into a special machine every 30 minutes. The machine measures how much hydrogen they breathe out.
- People who have lactose intolerance breathe out more hydrogen than normal
- The hydrogen breath test is positive for lactose malabsorption if the post-lactose breath hydrogen value rises greater than 20 ppm over the baseline measurement
Stool acidity test (Fecal PH Test)
- Human feces are normally alkaline. An acidic stool can indicate a digestive problem such as lactose intolerance or a contagion such as E. coli or rotavirus, or overgrowth of the acid-producing bacteria
Treatment focuses on the avoidance of dairy products, the use of lactose-free products, or the use of lactase supplements
 Osmosis |
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Lactose intolerance is due to lactase deficiency, which leads to a decrease in lactose absorption and increased osmotic load. This can manifest as abdominal pain, flatulence, and diarrhea. Lactose intolerance can be diagnosed with a positive hydrogen breath test and decreased stool pH. It can be treated by avoiding dairy products and lactase supplementation.
Play Video + QuizQuestion 1 |
Giardiasis Hint: Is due to ingestion of contaminated water. Can cause lactose intolerance.v | |
Celiac disease Hint: Causes chronic diarrhea. Usually due to sensitivity to gluten containing food. Can also cause lactose intolerance. | |
Lactose intolerance | |
Gastrinoma Hint: In addition to diarrhea, patient will also have ulcer symptoms. Can cause lactose intolerance. |
Question 2 |
urea breath test Hint: Urea breath test is used in diagnosing H. pylori infection. | |
hydrogen breath test | |
endoscopy Hint: Endoscopy and biopsy of the small intestine is done to diagnose celiac disease. | |
ileocolonoscopy Hint: Ileocolonoscopy is the diagnostic tool of choice to diagnose Crohn’s disease. |
Question 3 |
Osteopenia is a possible complication. Hint: See C for explanation | |
Hydrogen breath test is the diagnostic test of choice. Hint: See C for explanation | |
The congenital form is inherited as an autosomal dominant trait. | |
May be secondarily due to Crohn’s disease. Hint: See C for explanation |
Question 4 |
Supplemental calcium Hint: See D for explanation | |
Lactase enzyme preparations Hint: See D for explanation | |
Pre-hydrolyzed milk Hint: See D for explanation | |
Promethazine |
Question 5 |
Glucose and galactose | |
Glucose and sucrose Hint: See A for explanation | |
Fructose and galactose Hint: See A for explanation | |
Glucose and fructose Hint: See A for explanation |
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References: Merck Manual · UpToDate