Malabsorption Syndromes

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Malabsorption: Intro & Mechanisms - Gut Feeling Gone Wrong

  • Definition: Impaired intestinal absorption of nutrients, leading to deficiencies & GI symptoms (diarrhea, steatorrhea, weight loss).
  • Mechanisms:
    • Intraluminal Phase: Defective hydrolysis or solubilization.
      • E.g., Pancreatic insufficiency, Zollinger-Ellison syndrome, bacterial overgrowth, bile salt deficiency.
    • Mucosal Phase: Impaired epithelial transport.
      • E.g., Celiac disease, tropical sprue, Whipple's disease, lactase deficiency.
    • Post-mucosal Phase (Transport): Lymphatic obstruction.
      • E.g., Intestinal lymphangiectasia, lymphoma. Intestinal villi & malabsorption mechanisms

⭐ Steatorrhea (bulky, foul-smelling, fatty stools) is a hallmark of generalized malabsorption, particularly of fats due to impaired digestion or absorption across the intestinal mucosa or lymphatic transport issues. It often presents when fat malabsorption exceeds 7g/day (normal <6g/day).

Malabsorption: Clinical Clues & Workup - Spotting the Signs

  • Clinical Clues:
    • GI: Steatorrhea (bulky, greasy stools), weight loss, distension, flatulence.
    • Systemic: Anemia (Fe, B12, folate ↓), bone pain (Ca, Vit D ↓), edema (protein ↓), neuropathy (B12 ↓), bleeding (Vit K ↓).
  • Initial Workup:
    • Stool: Sudan III stain; 72-hr fecal fat (>7 g/day).
    • Blood: CBC, iron studies, B12/folate, albumin, Ca, PT/INR.
  • Diagnostic Approach:

⭐ Steatorrhea (>7 g/24h fecal fat) is a key indicator of malabsorption.

Celiac Disease - Gluten's Gut Grudge

  • Immune-mediated enteropathy triggered by gluten (gliadin in wheat, barley, rye) in genetically predisposed (HLA-DQ2/DQ8) individuals.
  • Pathology: Small intestinal inflammation (esp. duodenum, proximal jejunum) → villous atrophy, crypt hyperplasia, ↑ intraepithelial lymphocytes (IELs).
  • Clinical Features: Chronic diarrhea, steatorrhea, weight loss, abdominal pain, bloating. Children: failure to thrive. Iron deficiency anemia is common.
  • Diagnosis:
    • Serology: IgA anti-tissue transglutaminase (tTG) antibodies (screening); IgA anti-endomysial (EMA) antibodies (highly specific); Anti-deamidated gliadin peptide (DGP) antibodies.
    • Duodenal biopsy: Confirmatory; shows villous atrophy (Marsh classification).
  • Management: Lifelong strict gluten-free diet (GFD).
  • Complications: Malabsorption, osteoporosis, infertility, dermatitis herpetiformis, increased risk of T-cell lymphoma (EATL) & small bowel adenocarcinoma.

⭐ > Dermatitis herpetiformis, an intensely pruritic papulovesicular rash typically on extensor surfaces (elbows, knees, buttocks), is a cutaneous manifestation highly specific for celiac disease.

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Other Key Syndromes - The Malabsorption Medley

  • Whipple Disease:

    • Infection by Tropheryma whipplei (Gram-positive actinomycete).
    • Symptoms: Arthralgia, weight loss, diarrhea, abdominal pain, neurological & cardiac issues. 📌 Mnemonic: "Foamy Whipped cream in a CAN" (Foamy macrophages, Cardiac, Arthralgia, Neurologic).
    • Dx: PAS-positive macrophages in intestinal biopsy; PCR. Rx: Prolonged antibiotics (e.g., Ceftriaxone then TMP-SMX).

    ⭐ PAS-positive, diastase-resistant granules in foamy macrophages within the small intestinal lamina propria are characteristic of Whipple disease.

  • Tropical Sprue:

    • Etiology unclear (?post-infectious); affects residents/visitors of tropical areas.
    • Features: Chronic diarrhea, steatorrhea, weight loss, megaloblastic anemia (folate & B12 deficiency).
    • Biopsy: Villous atrophy (milder than celiac), ↑intraepithelial lymphocytes, chronic inflammation. Rx: Tetracycline & folic acid.
  • Short Bowel Syndrome:

    • Reduced absorptive surface area post-surgical resection (e.g., Crohn's, volvulus).
    • Complications: Malnutrition, diarrhea, electrolyte imbalance, ↑oxalate kidney stones, gallstones.
  • Lactase Deficiency (Lactose Intolerance):

    • Deficiency of lactase enzyme (primary: adult-onset; secondary: mucosal injury).
    • Symptoms: Osmotic diarrhea, bloating, flatulence after lactose ingestion.
    • Dx: Lactose hydrogen breath test; empirical trial of lactose-free diet.

High‑Yield Points - ⚡ Biggest Takeaways

  • Celiac disease: HLA-DQ2/DQ8 linked, anti-tTG IgA positive; villous atrophy, crypt hyperplasia.
  • Tropical sprue: Affects jejunum & ileum; responds to antibiotics, folate.
  • Whipple disease: Tropheryma whipplei infection; PAS-positive macrophages in lamina propria.
  • Lactase deficiency: Osmotic diarrhea; normal villous morphology.
  • Pancreatic insufficiency: Steatorrhea from impaired fat digestion; common in chronic pancreatitis.
  • D-xylose test: Differentiates mucosal disease (abnormal) from pancreatic insufficiency (normal).

Practice Questions: Malabsorption Syndromes

Test your understanding with these related questions

A 35-year-old Caucasian female presents with anemia, malaise, bloating, and diarrhea. Past genetic testing revealed that this patient carries the HLA-DQ2 allele. The physician suspects that the patient's presentation is dietary in cause. Which of the following findings would definitively confirm this diagnosis?

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Flashcards: Malabsorption Syndromes

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The granules in macrophages in Whipple disease stain positive for _____ and are diastase resistant

TAP TO REVEAL ANSWER

The granules in macrophages in Whipple disease stain positive for _____ and are diastase resistant

PAS

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