Paediatrics: Chronic diarrhoea

Chronic diarrhoea

Chronic diarrhoea

Defined as diarrhoea persisting for >14 days. Many of the diseases that cause acute diarrhoea can lead on to chronic diarrhoea.

The pathophysiology may involve:

•   Reduced GI absorptive capacity, e.g. coeliac disease.

•   Osmotic diarrhoea, e.g. lactase deficiency.

•   Inflammatory, e.g. ulcerative colitis.

•   Secretory diarrhoea (rare), e.g. vasoactive intestinal peptide producing tumour.

Causes

Age 0–24mths

•   Malabsorption, e.g. post-infective gastroenteritis syndrome, lactose intolerance, cystic fibrosis, coeliac disease.

•   Food hypersensitivity, e.g. to cow’s milk protein.

•   Chronic non-specific diarrhoea (toddler diarrhoea); child is usually thriving.

•   Excessive fluid intake.

•   Protracted infectious gastroenteritis.

•   Immuno-deficiencies, including HIV.

•   Hirschsprung’s disease.

•   Rarer causes (intractable diarrhoea) include congenital mucosal transport defects and autoimmune enteropathy.

•   Tumours (secretory diarrhoea).

•   Fabricated induced illness.

Older children

•   Inflammatory bowel disease (IBD).

•   Constipation (spurious diarrhoea).

•   Malabsorption—see Causes.

•   Irritable bowel syndrome (IBS).

•   Chronic infections, including giardiasis, bacterial overgrowth, and pseudomembranous colitis.

•   Laxative abuse.

•   Excessive fluid intake.

•   Fabricated induced illness.

History

Nature and frequency of stool, presence of undigested food, relationship to diet changes (e.g. weaning) or travel, stool blood, or mucus, weight loss.

Examination

•   Features of malnutrition or other illness, e.g. peri-anal disease in inflamma-tory bowel disease, or finger clubbing in cystic fibrosis.

Investigations

• Stool: inspection; microscopy for bacteria or parasites, leucocytes, fat globules (pancreatic diseases), fatty acid crystals (diffuse mucosal defects); culture; pH (<5.5 = carbohydrate malabsorption); reducing substances (>0.5% = carbohydrate malabsorption); faecal occult blood (colitis); electrolytes (i Na⁺ and K⁺ = secretory diarrhoea; ‘rise’Cl^– = congenital chloridorrhoea).

Blood: U&E; FBC (d Hb = haematinic deficiency or blood loss; ‘rise’eosinophil = food hypersensitivity or parasites); ‘rise’CRP/ESR (inflammatory); blood gas; radioallergosorbent test (RAST) (food allergy); hormone level (vanillylmandelic acid (VMA), catecholamines, vasoactive intestinal polypeptide (VIP)) for secretory tumours.

Radiology: AXR, ultrasound, barium meal and follow through.

Other: breath hydrogen test (lactose malabsorption or bacterial overgrowth); GI endoscopy biopsy (e.g. upper for coeliac disease, upper and lower for suspected IBD); sweat test/genetic testing (CF); rectal biopsy (Hirschsprung’s disease).

Treatment

• Treat underlying cause.

• Nutritional intervention if deficiencies are present.

• Antibiotics are only useful if systemic illness or prolonged infection is present, e.g. Salmonella, Campylobacter, giardiasis, or amoebiasis.

• Rarely, other drug treatment may be useful, e.g. loperamide or cholestyramine.

Chronic non-specific diarrhoea (toddler diarrhoea)

• Occurs from 6mths to 5yrs.

• Presents with colicky intestinal pain, ‘rise’flatus, abdominal distension, loose stools with undigested food (‘peas and carrots’ stools).

• Child is otherwise well and thriving.

• Examination and investigations are normal.

Treatment 

Reassurance; dietary (i fat intake; normalize fibre intake; ‘fall’ milk, fruit juice, and sugary drink intake); loperamide occasionally may be necessary.

Encopresis

• Voluntary defaecation in unacceptable places, including the child’s pants in older children.

• No organic abnormality is present; it is a symptom of an emotional disorder.

• It is three times more common in boys.

•   Once organic disease or spurious diarrhoea secondary to constipation with loading are excluded, consider behavioural problems and referral to a child and adolescent psychiatrist.