Gastrointestinal

Question 1

What is the management for intestinal lymphangiectasia?

Answer 1

Dietary modification:
High-protein, low-fat diet.
Medium-chain triglycerides (MCTs) to bypass lymphatic absorption.

Supplementation:
Fat-soluble vitamins (A, D, E, K).
Calcium and vitamin D for bone health.

Medical therapy:
Octreotide for refractory cases (reduces lymph flow).
Diuretics for edema and effusions.

Surgical intervention:
Reserved for localized lymphatic obstruction.

Question 2

How is intestinal lymphangiectasia diagnosed?

Answer 2

Laboratory tests:
Hypoalbuminemia, hypoglobulinemia, and lymphopenia.
Stool alpha-1 antitrypsin clearance (elevated).
Endoscopy:
White-yellow villi due to dilated lacteals.
Histology:
Dilated lymphatic vessels in the intestinal mucosa and submucosa.
Imaging:
Lymphangiography or CT for lymphatic obstruction.

Question 3

What are the clinical features of intestinal lymphangiectasia?

Answer 3

Chronic diarrhea (steatorrhea in severe cases).
Peripheral edema (due to hypoalbuminemia).
Recurrent infections (due to lymphocyte loss).
Ascites or pleural effusion (due to protein leakage).
Failure to thrive in children.

Question 4

What are the types of intestinal lymphangiectasia?

Answer 4

Primary (congenital): Idiopathic or hereditary, often linked to abnormal lymphatic development.
Secondary (acquired): Due to conditions like:
Congenital heart disease.
Lymphatic obstruction from tumors, infections, or fibrosis.
Sarcoidosis or Crohn’s disease.

Question 5

What is the pathophysiology of intestinal lymphangiectasia?

Answer 5

The disorder arises from obstruction or malformation of intestinal lymphatics, causing:

Leakage of protein-rich lymph into the intestinal lumen.
Loss of albumin, immunoglobulins, and lymphocytes.
Hypoproteinemia, lymphopenia, and malabsorption.

Question 6

What is intestinal lymphangiectasia?

Answer 6

Intestinal lymphangiectasia is a rare disorder characterized by dilation of intestinal lymphatic vessels, leading to protein-losing enteropathy, malabsorption, and lymphedema.

Question 7

What is abetalipoproteinemia?

Answer 7

Abetalipoproteinemia is a rare autosomal recessive disorder characterized by the inability to synthesize apolipoprotein B-containing lipoproteins (chylomicrons, VLDL, and LDL), leading to fat malabsorption and systemic complications.

Question 8

What is the genetic mutation responsible for abetalipoproteinemia?

Answer 8

Abetalipoproteinemia is caused by mutations in the MTTP (microsomal triglyceride transfer protein) gene, leading to defective assembly and secretion of apolipoprotein B-containing lipoproteins.

Question 9

What is the pathophysiology of abetalipoproteinemia?

Answer 9

Defective MTTP impairs assembly of apolipoprotein B48-containing lipoproteins in the intestine and liver.
Leads to:
Fat malabsorption (steatorrhea).
Deficiency of fat-soluble vitamins (A, D, E, K).
Very low or absent plasma levels of chylomicrons, VLDL, and LDL.

Question 10

What are the clinical features of abetalipoproteinemia?

Answer 10

Gastrointestinal symptoms:
Diarrhea, steatorrhea, and failure to thrive in infancy.
Neurological symptoms:
Ataxia, muscle weakness, and peripheral neuropathy due to vitamin E deficiency.
Ophthalmologic symptoms:
Retinitis pigmentosa, night blindness.
Hematologic features:
Acanthocytosis (spiky red blood cells) and anemia.

Question 11

How is abetalipoproteinemia diagnosed?

Answer 11

Blood tests:
Very low levels of cholesterol, triglycerides, and apolipoprotein B.
Acanthocytosis on peripheral blood smear.

Vitamin levels:
Deficiency of fat-soluble vitamins (A, D, E, K).

Genetic testing:
MTTP gene mutation.

Biopsy findings:
Intestinal biopsy shows lipid-laden enterocytes in the small intestine.

Question 12

What is the management of abetalipoproteinemia?

Answer 12

Dietary modifications:
High-calorie diet with medium-chain triglycerides (MCTs).
Low-fat diet to minimize steatorrhea.
Vitamin supplementation:
Fat-soluble vitamins: Vitamin A, D, E, and K.
Vitamin E is critical to prevent neurologic damage.
Regular monitoring:
Neurological, ophthalmologic, and nutritional status.

Question 13

What enzyme deficiency causes lactose intolerance?

Answer 13

Lactase (β-galactosidase) deficiency in the brush border of the small intestine.

Question 14

What are the two main substrates produced by lactase?

Answer 14

Glucose and galactose

Question 15

How does undigested lactose lead to symptoms?

Answer 15

Fermentation by gut bacteria produces hydrogen gas, short-chain fatty acids, and osmotic diarrhea.

Question 16

What are the primary types of lactase deficiency?

Answer 16

1. Primary lactase deficiency (age-related decline).
2. Secondary lactase deficiency (due to damage, e.g., celiac disease, infections).
3. Congenital lactase deficiency (autosomal recessive, rare).

Question 17

What are the hallmark symptoms of lactose intolerance?

Answer 17

• Abdominal pain (cramping).
• Bloating.
• Flatulence.
• Watery diarrhea.

Question 18

What is the gold standard test for diagnosing lactose intolerance?

Answer 18

Lactose hydrogen breath test: Elevated hydrogen >20 ppm after lactose ingestion.

Question 19

What is an alternative diagnostic test?

Answer 19

Lactose tolerance test: Blood glucose rise <20 mg/dL after lactose ingestion.

Question 20

Management of lactose intolerance?

Answer 20

1.Avoidance of lactose-containing foods (e.g., milk, soft cheeses)
2.Lactase supplements (taken with meals) 3.Lactose-free milk, plant-based milk (soy, almond), hard cheeses, yogurt
4.calcium and vitamin D supplementation To prevent deficiencies due to dairy restriction.

Question 21

What is celiac disease?
.

Answer 21

An immune-mediated disorder triggered by gluten ingestion in genetically susceptible individuals, leading to small intestinal villous atrophy

Question 22

What are the key genetic associations in celiac disease?

Answer 22

• HLA-DQ2 (95% of cases).
• HLA-DQ8 (5% of cases).

Question 23

What components of gluten trigger the immune response?

Answer 23

Alpha Gliadin peptides (a component of gluten) activate T cells.

Question 24

What enzyme modifies gliadin to make it more immunogenic?

Answer 24

Tissue transglutaminase (tTG)

Question 25

What are the classic gastrointestinal symptoms of celiac disease?

Answer 25

Chronic diarrhea,
steatorrhea,
bloating,
flatulence, and
weight loss

Question 26

What are some extraintestinal manifestations of celiac disease?

Answer 26

• Anemia: Iron deficiency (most common).
• Neurological: Peripheral neuropathy, ataxia, seizures.
• Dermatological: Dermatitis herpetiformis (pruritic, vesicular rash).
• Musculoskeletal: Osteopenia/osteoporosis.
• Endocrine: Amenorrhea, infertility.

Question 27

What should you suspect in a patient with refractory iron-deficiency anemia unresponsive to oral iron therapy?

Answer 27

Celiac disease

Question 28

What conditions are commonly associated with celiac disease?

Answer 28

Dermatitis herpetiformis
Autoimmune diseases: Type 1 diabetes, autoimmune thyroiditis, Addison’s disease.
Down syndrome.
Selective IgA deficiency.
IgA nephropathy
Hypersensitivity pneumonitis/ bird fancier lung
Lymphocytic Colitis
Cerebral calcification with epilepsy