PANCE Blueprint GI and Nutrition (9%)

Lactose intolerance

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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What constitutes a positive hydrogen breath test?
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

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 which 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 is 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 avoidance of dairy products, use of lactose-free products, or the use of lactase supplements

Lactose Intolerance Osmosis

Question 1
A 9-year old boy was brought to the clinic by his mother on account of 5-month history of abdominal cramps, bloating, diarrhea and flatulence that occur usually about 2 hours after ingesting milk. What is his most likely diagnosis?
A
Giardiasis
Hint:
Is due to ingestion of contaminated water. Can cause lactose intolerance.v
B
Celiac disease
Hint:
Causes chronic diarrhea. Usually due to sensitivity to gluten containing food. Can also cause lactose intolerance.
C
Lactose intolerance
D
Gastrinoma
Hint:
In addition to diarrhea, patient will also have ulcer symptoms. Can cause lactose intolerance.
Question 1 Explanation: 
Lactose intolerance typically present with abdominal cramps, bloating, and flatulence that occur from about 1 hour to a few hours following ingestion of milk or dairy products.
Question 2
Which of the following is the diagnostic test of choice for lactose intolerance?
A
urea breath test
Hint:
Urea breath test is used in diagnosing H. pylori infection.
B
hydrogen breath test
C
endoscopy
Hint:
Endoscopy and biopsy of the small intestine is done to diagnose celiac disease.
D
ileocolonoscopy
Hint:
Ileocolonoscopy is the diagnostic tool of choice to diagnose Crohn’s disease.
Question 2 Explanation: 
Hydrogen breath test is the diagnostic test of choice for lactose intolerance/lactase deficiency. Subjects are administered 50 g of lactose after an overnight fast, a rise in breath hydrogen of >20 ppm within 90 minutes is a positive test, indicative of bacterial carbohydrate metabolism.
Question 3
Which of the following statements regarding lactose intolerance is incorrect?
A
Osteopenia is a possible complication.
Hint:
See C for explanation
B
Hydrogen breath test is the diagnostic test of choice.
Hint:
See C for explanation
C
The congenital form is inherited as an autosomal dominant trait.
D
May be secondarily due to Crohn’s disease.
Hint:
See C for explanation
Question 3 Explanation: 
The congenital form is inherited as an autosomal dominant trait. The congenital form is inherited as an autosomal recessive trait. All other statements are correct.
Question 4
Treatment options for lactose intolerance include all of the following except
A
Supplemental calcium
Hint:
See D for explanation
B
Lactase enzyme preparations
Hint:
See D for explanation
C
Pre-hydrolyzed milk
Hint:
See D for explanation
D
Promethazine
Question 4 Explanation: 
Promethazine is an anti-emetic and anti-allergy. It has no role in the management of lactose intolerance. All other options are correct.
Question 5
Lactase enzyme breaks down lactose into
A
Glucose and galactose
B
Glucose and sucrose
Hint:
See A for explanation
C
Fructose and galactose
Hint:
See A for explanation
D
Glucose and fructose
Hint:
See A for explanation
Question 5 Explanation: 
Lactase enzyme breaks down lactose into glucose and galactose.
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