Malabsorption

Malabsorption

1. manifestations of disorders affecting digestion or absorption of nutrients

   • abnormal stools
     • true malabsorption stool
       • hard to flush down the toilet
       • odour pervades whole house
     • colour is poor guide to abnormality
   • failure to thrive or poor growth
     • seen in most but not all cases
     • inapprop to ix kids for malabsorption as a cause of failure to thrive when dietary intake is low & other sx absent
   • specific nutrient deficiencies

2. reliable dietary assessment is important

3. can be pan-malabsorption

   • poor absorption of many nutrients

4. can be highly specific

   • e.g. Zn malabsorption
     • acrodermatitis enteropathica

5. causes of nutrient malabsorption

   • cholestatic liver disease or biliary atresia
     • bile salts no longer enter duodenum in bile
       • -> defective solubilisation of products of triglyceride hydrolysis
         • -> fat and fat-soluble malabsorption
   • exocrine pancreatic dysfunction
     • e.g cystic fibrosis
     • absent lipase, proteases & amylase
       • -> defective triglyceride, protein and starch digestion (pan-malabsorption)
   • small intestinal mucosal disease
     • loss of absorptive surface area
       • e.g. coeliac disease
     • specific enzyme defects
       • e.g. lactase deficiency ff gastroenteritis
         • common in Black & Oriental races
     • specific transport defects
       • e.g. glucose-galactose malabsorption
         • severe life-threatening diarrhoea with 1st milk feed
       • acrodermatitis enteropathica
         • zinc malabsorption
           • erythematous rash of mouth & anus
   • lymphatic leakage or obstruction
     • chylomicrons (containing absorbed lipid) unable to reach thoracic duct & sys circulation
       • e.g. intestinal lymphangiectasia (abnormal lymphatics)
   • short bowel syndrome
     • small intestinal resection
       • due to congenital abnormalities or necrotising enterocolitis
       • -> nutrient, water & electrolyte malabsorption
   • loss of terminal ileal function
     • e.g. resection or Crohn disease
     • absent bile acid and absent B12 absorption