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MALABSORPTION IN CHILDREN �

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Definition�

Definitions:

  • (a) Clinical problems arising from variety basic small intestinal dysfunction leading change in character of stools – intermittently looser or permanent looser and more frequent stool.

 

  • (b) Malabsorption Syndrome: A number of disorders coeliac disease, cystic fibrosis, tropical sprue, short bowel syndrome.

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      • (a) and (b) lead to failure of small intestine to absorb nutrients e.g. Macronutrients (proteins, carbohydrate, fats). Micronutrients (vitamins and minerals)
  • Specific or general nutritional deficiency may be present

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SIGNS AND SYMPTOMS�

  • Failure to thrive
  • Abdominal distension and cramps
  • Large sticky stools
  • Watery stool
  • Steatorrhoea

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Pancreatic

Bicarbonate

Chymotrypsin

Amylase

Lipase

Bile salts

Mucus cells

Gastric

Pepsin

Hcl

Salivary

Amylase

IN

Carbohydrate, fat, protein, water, Electrolyte, Vitamins

Diet

OUT

Iron

Carbohydrate

Protein

Fat

Water

Sodium

Potassium

Vitamin B

Magnesium

Bile salts

Stool

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Pathophysiology:

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Sites of digestion

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Carbohydrate Digestion and Absorption

Intraluminal

INTESTINAL

Starch

Lactase

Sucrase

Maltose

Maltriose

Dextrins

Maltase

Maltase

Dextrinase

Glucose

Brush Border

Amylase

Cell Transport

Active Transport

Galactose

Glucose

Active Transport

Active Transport

Facilitated

Diffusion

Glucose

Fructose

ɣ

ɣ

Lactose

Sucrose

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Comparative Pathways of mechanisms of absorption of fat, Protein and carbohydrates

Pancreas

Liver

Jejunum

Lymphatics

Blood

TG

Protein

Carbohydrate

  1. Lipolysis

FA

BMG

Peptides

Amino Acids

Oligosaccharides

Disaccharides

2. Micellarization

Mixed micelle with bile Acid

3. Absorption

TG

Chylomicrons

Amino Acids

Monosaccharides

4.Delivery

NB: It is possible to have only malabsorption of fats or all the 3 sources of calories

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NORMAL MECHANISMS OF FAT DIGESTION/ABSORPTION�

  • Luminal Events
  • Pancreatic or Lipolytic Phase
    • Little hydrolys in the stomach lingual lipase
    • Triglyceride hydrolyse by pancreatic lipase end products:
      • glycerol,
      • fatty acids

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  • Luminal events:
  • Micellar Solubilization
  • Fatty acids and β monoglyceride dissolved into micellar structure – bile acids aqueous solution
  • Gets into intimate contact with micro villous boarder

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  • MUCOSAL EVENTS
  • Mucosal Uptake
  • β monoglyceride diffuses across cell membrane
  • FA
  • Re-esterification BMG and FA to TG
  • TG + protein + Lipoprotein + chylomicrons
  • This product released into submucosal tissue of small intestine

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  • Delivery Phase
  • The chylomicrons are released into Central lacteals to the lymph, thoracic duct thence to circulation and sites of utilization, storage etc.

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Localisation of sites of Absorption in GIT

Jejunum

Ileum

Fat

Fats, Proteins

CHO, Vitamins

Bile Acids (passive)

Bile Acids (Active)

B12

NB: Adequate conc of Bile Acids in jejunum is crucial for solubilization

Critical micellar solubilisation

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CAUSES OF MALABSORPTION:

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A. Conditions affecting liminal events (Pancreas Liver)

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B. Brush border – morphologic anatomical/enzymopathies

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C. Miscellaneous

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Conditions Affecting Luminal events�

  • Pancreatic insufficiency
  • Malnutrition
  • Pancreatitis
  • Cystic Fibrosis
  • Juvenile Tropical Pancreatitis Syndrome

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Pancreatic disorders continued �

  • Juvenile Tropical Pancreatitis Syndrome
  • Features
  • Abdominal pain
  • Diabetes mellitus
  • Malabsorption
  • Pancreatic calcification
  • Malnutrition
  • Diagnosis
  • Abdominal x-ray
  • Serum amylase during episodes of pain

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Brush Border Morphological Abnormalities�

  • Protein losing enteropathies – CMA
  • Coeliac disease
  • Kwashiorkor

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Girdiasis

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COELIAC DISEASE�

  • Permanent inability to tolerate dietary wheat and rye gluten
  • Features
  • Impaired intestinal absorption
  • Flat mucosa in the duodenum and jejunum
  • Clinical and histological improvement when diet is free of gluten
  • Clinical and histological relapse following reintroduction of dietary gluten

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DISORDERS OF CARBOHYDRATE ABSORPTION

Intraluminal digestion of starch

    • Neonatal period
    • Pancreatic duct occlusion
    • Transient physiological immaturity

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Brush border digestion

    • Lactase deficiency
      • Acquired
      • Congenital
      • Secondary to mucosal injury

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DISORDERS OF CARBOHYDRATE ABSORPTION

    • Sucrase isomaltase deficiency
    • Trehalase deficiency

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Monosaccharide transport

    • Congenital glucose-galactose malabsorption
    • Acquired glucose-galactose malabsorption

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Miscellaneonus�

  • Deprivation dwarfism
  • Chronic renal disease
  • Chronic upper respiratory infection
  • Asociated with large intestinal dysfunction
  • ulcerative colitis
  • TB

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INVESTIGATIONS�

  • Imaging including contrast study
  • Quantitative and Qualitative stool fat
  • Xylose absorption tests
    • Urine
    • Fasting Blood
  • B12 absorption
  • Small intestinal biopsy

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  • CHO screening tests
    • Stool pH
    • Osmotic gap
      • Measured by
        • Stool osmolality
        • Stool Na, K

Osmolality ≥ 2 x sum of Na and K implies presence of short chain fatty acid