Malabsorption Syndromes

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Malabsorption Overview - Leaky Gut Saga

  • Definition: Impaired intestinal absorption of nutrients, leading to deficiencies & systemic effects.
  • "Leaky Gut" Concept: Increased intestinal permeability due to compromised tight junctions (e.g., zonulin dysregulation). Allows passage of undigested food particles, toxins, & microbes, triggering inflammation.
  • Mechanisms:
    • Pre-mucosal (Luminal): Defective hydrolysis (e.g., Pancreatic insufficiency, ↓bile salts).
    • Mucosal (Absorptive): Reduced surface area, enzyme defects, transport issues (e.g., Celiac disease, Crohn's disease).
    • Post-mucosal (Obstructive): Lymphatic blockage (e.g., Whipple's disease, intestinal lymphoma).

⭐ The D-xylose test helps differentiate between maldigestion (pancreatic) and malabsorption (small intestinal mucosal disease); it will be normal in pancreatic insufficiency. Intestinal barrier with tight junctions and immune cells

Clinical Manifestations - Telltale Tummy Tales

  • Growth: Failure to thrive (FTT), poor weight gain (<5th percentile), muscle wasting.
  • GI Tract:
    • Chronic diarrhea (>2 wks): watery, fatty.
    • Steatorrhea: bulky, pale, foul, greasy stools.
    • Abdominal distension, pain, borborygmi.
    • Anorexia, vomiting.
  • Nutrient Deficiency Clues:
    • Anemia (Iron, B12, Folate): pallor, glossitis.
    • Bleeding (Vit K): bruising, petechiae.
    • Bone (Vit D, Ca): rickets, tetany.
    • Eyes/Skin (Vit A, Zn): night blindness, xerophthalmia, dermatitis.
    • Protein: Edema. Pediatric Malabsorption Syndromes: Clinical Presentation

⭐ Failure to thrive (FTT), chronic diarrhea, and abdominal distension form a classic triad for pediatric malabsorption.

Celiac Disease Deep Dive - The Gluten Grudge

  • Pathophysiology: Immune response to gluten (gliadin) in HLA-DQ2/DQ8 individuals. Results in villous atrophy, crypt hyperplasia, ↑ Intraepithelial Lymphocytes (IELs).
  • Clinical Features (Peds): Failure to thrive (FTT), chronic diarrhea, abdominal distension, Iron Deficiency Anemia (IDA), short stature. Dermatitis herpetiformis (DH).
  • Diagnosis:
    • Serology:
      • Anti-tTG IgA (Best initial test). Check total IgA.
      • Anti-EMA IgA (Most specific).
      • Anti-DGP IgA/IgG (if IgA deficient or <2 yrs).
    • Duodenal Biopsy (Gold Standard): Marsh classification (e.g., Marsh III: villous atrophy). Celiac disease duodenal biopsy and endoscopy
    • Diagnostic Algorithm:
  • Management: Lifelong strict Gluten-Free Diet (GFD). Nutritional support.
  • Mnemonic (Symptoms - 📌 CELIAC):
    • Chronic diarrhea
    • Emesis
    • Lethargy
    • Irritability
    • Abdominal pain/distension
    • Constipation (sometimes)

⭐ *ESPGHAN: Symptomatic children with Anti-tTG IgA >10x ULN + positive EMA (2nd sample) may avoid biopsy for diagnosis of Celiac Disease.

Key Syndromes & Workup - Suspects & Sleuth Kits

  • Key Syndromes & Primary Clues:

    SyndromeKey Feature(s)Primary Test(s)
    Cystic Fibrosis (CF)Pancreatic insufficiency (steatorrhea), chronic lung diseaseSweat chloride (>60 mEq/L), ↓Fecal elastase, Genetic test
    Lactose IntoleranceOsmotic diarrhea, bloating post-dairyHydrogen breath test, Stool reducing substances (+), acidic pH
    GiardiasisFoul steatorrhea, malabsorption; contaminated waterStool microscopy (O&P - multiple), ELISA
    Short Bowel SyndromePost-surgical resection, nutrient deficienciesClinical Hx, Imaging, ↓D-xylose test
  • General Workup (Sleuth Kit):

    • Stool: Microscopy (Giardia), Sudan stain (fat↑), fecal elastase, pH, reducing substances.
    • Blood: CBC (anemia), albumin, vitamins (A,D,E,K), PT/INR, IgA anti-tTG (Celiac screen).
    • Breath Tests: Hydrogen (lactose intolerance, SIBO).
    • D-xylose Test: Assesses proximal small bowel mucosal integrity.

      ⭐ D-xylose test: Normal in pancreatic exocrine insufficiency (e.g., CF) as absorption is independent of pancreatic enzymes, but abnormal in small intestinal mucosal disease (e.g., Celiac, SBS).

High‑Yield Points - ⚡ Biggest Takeaways

  • Celiac Disease: Gluten-sensitive enteropathy, villous atrophy, anti-TTG/EMA antibodies.
  • Cystic Fibrosis: Pancreatic insufficiency (steatorrhea), meconium ileus, elevated sweat chloride.
  • Lactose Intolerance: Lactase deficiency, osmotic diarrhea, positive hydrogen breath test.
  • Abetalipoproteinemia: AR, absent Apolipoprotein B, acanthocytes, severe fat malabsorption, neurological deficits.
  • Shwachman-Diamond Syndrome: Pancreatic exocrine insufficiency, neutropenia, skeletal abnormalities.
  • Giardiasis: Common parasite, foul-smelling watery diarrhea, diagnosis by stool antigen/microscopy.
  • Short Bowel Syndrome: Post-surgical, reduced absorptive surface, requires TPN, risk of SIBO (Small Intestinal Bacterial Overgrowth).

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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Infant presenting with failure to thrive, steatorrhea, _____ in the peripheral smear is suggestive of _____.

TAP TO REVEAL ANSWER

Infant presenting with failure to thrive, steatorrhea, _____ in the peripheral smear is suggestive of _____.

acanthocytosis; abetalipoproteinemia

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