Inflammatory Bowel Disease

Refer under 16s to Paed gastro. Patients prefer cf adult services!

Microbiome pivotal to development of IBD (among other things, eg allergy).  Plus genetic factors – first degree relatives of Crohn’s patients have up to 35x greater risk!  When risk assessed on basis of genotype and smoking, 32% of apparently asymptomatic had evidence of small bowel inflammation (and quite a few had moderate-severe inflammation).

In this study calprotectin over 150microg/g was 95% specific for inflammation (32.6% sensitive). [Poster 2016]

Higher calprotectin in relatives correlates with dysbiosis (ie lower microbial diversity and shifts in composition, including more enterobacteriaceae). [Cell Molec Gastroenterol Hepatol. 2016 Jul 4. doi: 10.1016/j.jcmgh.2016.06.004]

Pathology is leaky tight junctions, innate and adaptive immunity defects.

Types:

  • Crohns  – transmural, skip lesions, mouth to anus.  70% have granulomas.
  • Ulcerative colitis – always involves anorectal region, continuous, more superificial
  • IBDU (undifferentiated)- mucosal only, colon only (cf rectal in UC).  Some evolve into more typical Crohns or UC.

Still rising incidence of Crohns in Scotland (5x in 34 years)!

Presentation

Abdominal pain, diarrhoea (esp bloody), weight loss.  Nocturnal stooling.

Small bowel IBD can present like anorexia nervosa!

Acute/chronic “appendicitis” = terminal ileum Crohns.

Drop in height centile can precede gut symptoms.

Clinical Features

  • Cobblestoning of oral mucosa, buccal tags
  • Swollen joints,
  • Erythema nodosum,
  • Anal fissures or tags.
  • Growth parameters.
  • Ileocaecal mass.
  • Pyoderma gangrenosum is a rare association.

Investigations

Calprotectin is a neutrophil protein.  False pos in infection, polyps, under 5s.  Reduces endoscopy rate by 35%, and earlier diagnosis for some.

200-250 is starting to get specific.  Don’t do under 5yrs!

MR better detail, less radiation for small bowel.  But low availability and expertise.

Treatment

2016 BSPGHAN ArchDisChild guidelines

Emphasis on mucosal healing, not just symptoms eg bloods, calprotectin, imaging.

Crohn’s disease

Exclusive nutritional mx 6-8/52 is preferred for active luminal Crohns, mucosal healing better cf steroids.  Microbiome changes, but not to normal!

Solid food version of Modulen being developed.

Early Azathioprine for maintenance.  (Mercaptopurine more appropriate for young children).  Check TPMT enzyme activity to avoid toxicity, start full dose rather than titrating up (2mg/kg unless enzyme pos).  Check metabolite levels if poor response or side effects. Using “discordant metabolites” (6TG, 6MP) benefit from split dosing.

MTX for failed aza (preferred if arthritis).

Surgery good for local disease – no need to fail medical!

Weighted paed CD activity index (wPCDAI) – app available!  PUCAI app not strictly legal…

Anti-TNF treatment – occ non-responders, check levels first!  First line in US, similar to rheumatology: use best Rx first!  Biosimilars available now, cheaper but more complex to make so higher risk of reactions?  Prescribe by brand name.  So far no concerns.

VEDOLIZUMAB – vs gut-tropic lymphocyte migration.  Approved in adults.

20% Crohns don’t get change in bloods with acute exacerbations!  Check stool cultures and C diff, can start EEN pending results.

See Ulcerative Colitis.

Prognosis

Mean final height in CD 2.4cm below target.

Transition only when completed growth and development and without education/psych issues.

SSPGHAN guidelines 2014

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