Paediatrics: Malabsorption

Malabsorption

Defined as subnormal intestinal absorption of dietary constituents with excessive faecal nutrient loss. The prognosis depends on the cause. Reduced adult height, teeth enamel defects, and osteoporosis may result from long-term malabsorption. Causes are listed in Box 10.5.

Presentation

•   Diarrhoea.

•   Steatorrhoea.

•   Flatulence.

•   FTT/weight loss.

•   Muscle wasting.

•   Abdominal distension.

•   Peri-anal excoriation.

•   Delayed puberty.

•   Features of underlying illness, e.g. abdominal pain in Crohn’s disease.

•   Signs of nutritional deficiency states, e.g. ascites due to hypoalbuminaemia.

Investigations

Initial screening tests should include: FBC; U&E; creatinine; albumin; total protein; Ca²⁺; PO₄^3– ; LFT; iron status, coeliac antibody screen; coagulation screen, stool M,C&S.

If diagnosis still unclear, consider:

•   Upper GI endoscopy with biopsy to look for an enteropathy, ileocolonoscopy if features suggest colitis (ensure clotting screen normal before procedure).

•   Sweat test.

•   Immune function tests.

•   Faecal fat measurement.

•   Facal elastase.

•   Faecal A₁-antitrypsin.

•   Exocrine pancreatic function tests.

Treatment

•   Treat underlying disease, e.g. metronidazole for giardiasis, gluten-free diet for coeliac disease.

•   Supplemental digestive enzymes, e.g. pancreatic enzymes in cystic fibrosis.

•   Nutritional supplements to correct deficiencies.

•   PN if malabsorption severe or slow to recover.

Box 10.5 Causes of malabsorption

Intraluminal digestive defect

• Carbohydrate intolerance (most commonly lactose intolerance)

• Protein–energy malnutrition

• Cystic fibrosis

• Shwachman–Diamond syndrome

• Chronic pancreatitis

• Cholestasis

• Pernicious anaemia

• Specific digestive enzyme deficiency, e.g. lipase

Mucosal abnormality

• Coeliac disease

• Short bowel syndrome

• Dietary protein intolerance, e.g. milk protein allergy

• Intestinal infection or parasites, e.g. giardiasis

• IBD

• Abetalipoproteinaemia (disorder of lipid metabolism—FTT, steatorrhoea, progressive ataxia, retinitis pigmentosa, acanthocytes on FBC)

• Protein–energy malnutrition; intestinal venous or lymphatic obstruction, e.g. congestive cardiac failure, intestinal lymphangiectasia

Miscellaneous

• Immunodeficiency syndromes, e.g. HIV

•   Drug reaction, e.g. cytotoxics, post-radiation

•   Bacterial overgrowth, e.g. pseudo-obstruction