crohns
Table of Contents
Crohn's disease
see also:
introduction
- 1st described by Crohn, Ginzberg, and Oppenheimerf in 1932.
epidemiology
- rare, but common in exams as young patients who speak English readily available!
- onset usually between 15-40yrs age
- the age of onset has a bimodal distribution:
- first peak occurs between the ages of 15-30 years
- second peak occurs between the ages of 60-80 years
- M=F
- 3-8x risk in Jewish than non-Jews
- incidence in USA has been doubling every 10yrs for past 30yrs
- in both Europe and North America, higher incidence rates have been characterized in more northern latitudes
- prevalence in US ~7 cases per 100,000 population
- incidence rates in Europe range from 0.7 to 9.8 cases per 100,000 persons
pathology
- chronic granulomatous inflammation extending through ALL layers of bowel wall & involving LNs
- it appears the yeast fungus Debaryomyces hansenii may have a role in impairing healing of gut ulcers in patients with Crohns disease by increasing the levels of a cytokine called CCL5 (chemokine ligand 5)
- important distinguishing features from ulcerative colitis:
- involvement of all layers not just mucosa & submucosa
- skip lesions (lips to anus) rather than continuous lesions
- rectal involvement NOT common BUT anorectal complications such as fistulae/abscesses are common
- characteristic small bowel involvement
clinical features
- being rare, initial presentation usually as a “mask” for other conditions (but features of > 1 mask may be present):
- terminal ileitis presenting as RIF “appendiceal” mass
- chronic diarrhoea, abdo. cramps, fever, anorexia, weight loss
- left colitis presenting with pain and PR bleeding
- anorectal involvement presenting as perianal suppuration (~50% of presentations):
- 1st perianal abscess usually just incised and drained
- 2nd recurrence, one excludes diabetes
- 3rd recurrence, one needs to exclude Crohn's
- regional (segmental) colitis presenting as subacute bowel obstruction
- extragastrointestinal presentations (each occur in 10% of pts) (rarest presentation):
- iritis
- episcleritis
- erythema nodosum
- arthritis - eg. monoarticular, sacroiliitis or ankylosing spondylitis
- aphthous ulcers
other complications of Crohns
- gallstones are found in 35-60%
- malabsorption ⇒ diarrhoea
- bowel strictures
- fistulae ⇒ UTI, etc
- 2-3% develop toxic megacolon
- risk of large & small bowel cancer in prolonged illness (15-20yrs)
- lymphoma of colon may occur
- drug Rx related:
- Cushing's syndrome, adrenal suppression, immunocompromise, etc from steroids
- neuropathy (long term metronidazole)
- nephropathy (cyclosporine)
- bone marrow suppression (azathioprine)
diagnosis of Crohn's disease:
confirmed by:
- sigmoidoscopy
- biopsy of perianal lesions/abscesses, rectum or other granulomatous lesions
- bowel contrast radiology:
- skip lesions
- non-involvement of rectum
- strictures
- 'rose thorn' ulcers
- 'cobblestone' mucosal surfaces
- associated carcinoma
other possible findings
- raised C reactive protein (CRP) is an indicator of disease activity
- 20% have raised liver function tests (LFTs)
- 60% of these patients have mild, transient raised LFTs and many are related to drug-induced cholestasis
- most of those with persistent changes were due to fatty liver disease and had a cholestatic picture 1)
- 10-40% are ANCA positive (cw 50-85% of patients with ulcerative colitis and 50-85% of those with primary sclerosing cholangitis (PCC), a chronic cholestatic liver disease that is strongly associated with IBD) 2)
- persistently high AP levels are suggestive of primary sclerosing cholangitis / primary biliary cirrhosis
differential diagnosis:
younger patients:
- invasive infectious enteritis (eg. Campylobacter, Shigella, C difficile)
- terminal ileitis
- 50-80% are due to Yersinia enterocolitis which may also have extraGIT manifestations:
- erythema nodosum, monoarticular arthritis BUT no perianal or skip lesions
elderly patients:
- infectious colitis - esp. enteropathogenic E.coli 0157:H7 in nursing home pts eating beef
general Mx of Crohn's disease:
- medical Rx is similar to UC but less effective (don't use to delay effective Sx for fistulae, etc):
- prednisolone 20-30mg/day orally provides symptom control but doesnt alter prognosis
- hydrocortisone acetate foam enemas i (125mg) 12-24h PR for 1-2wks then alternate days if rectal disease
- metronidazole 400mg bd o may help non-responders with perianal/colonic disease
- avoid in pregnancy
- courses should be < 3months to avoid neuropathies
- azathioprine (Imuran) 2mg/kg/d o may allow withdrawal of steroid Rx in pts with chronic symptoms
- avoid in pregnancy
- sulphasalazine may be tried, but no help in ileal disease & has no role in maintenance Rx
- cholestyramine 4-8g tds o may help if bile salt malabsorption causes diarrhoea
- cyclosporin 2.5-4mg/kg bd o for 3mths may help without inducing too much nephropathy
- in active disease:
- food intolerance (eg. cereals, milk, yeasts) may be present, so elemental diets may be as good as prednisolone, with re-introduction of foods one at a time maintains improvement without being boring
- if steatorrhoea, then give low fat diet
- if lactose intolerant, then lactose free diet
- only consider TPN if enteral route cannot be used
- surgery:
- surgery is never curative, unlike in UC
- bowel resections
- stricture relief
- aim to control symptoms
ED Mx of exacerbations of Crohn's disease
- exacerbations usually present as increased abdominal pain, anorexia, nausea and, often increased frequency of bowel actions
- iv fluids
- take bloods for FBE, U&E, CRP, ESR and other Ix (eg. HCG, LFT's) as indicated by clinical assessment - don't forget the abdominal pain could be unrelated to the Crohn's disease and thus consider other causes of abdominal pain as well as potential complications of Crohn's as outlined above.
- discuss with gastroenterology unit
- usually require admission and iv hydrocortisone 100mg qid in addition to usual Crohn's Rx
crohns.txt · Last modified: 2022/06/04 01:18 by gary1