Crohn's disease Flashcards
What is Crohn’s disease?
An inflammatory bowel disease that can affect both small and large intestine
Usually, start in the distal portion of the small intestine
Occurs in more developed countries
The incidence is bimodal with a peak in the young age range and one in older people. More common in adolescents and young people, also white people.
Affects the whole intestinal wall, mucosa and muscle layer.
If the disease progresses to the state requiring surgical intervention, 75% of those requiring small bowel resection will have a recurrence within 5 years and further surgery within 15 years
- can relapse even with surgeru
What causes Crohn’s disease?
Usually a combination of several factors
- Genetic –? prevalence is 35% monozygotic pairs which suggest strong links to genetics, over 70 genes have been associated with CD on 17 chromosomes. These include HLAS B27 and NOD2A, but mutations in an of them have been found to be the main cause of the condition. A number of Crohns patients have polymorphisms in these genes so there may be mutations in several genes.
- Environment
- Smoking –> can be a trigger
- Autoimmune response, immunological challenges
- Diet? Low consumption of dietary fibre
Where does Crohn’s affect?
Usually, beginning in the terminal ileum but can also affect other areas.
L1 –> Terminal ileum - 30% cases
L2 –> Colon - 20% cases
L3 –> Ileocolon - 50% cases
L4 –> Upper GI tract
L4 + L3 –> Upper GI tract and distal disease
What is the pathology of Crohn’s?
Deep ulcer type lesions, strictures and fistulation (forming a link between the gut and another structure), very serious complication that requires surgery
What does Crohn’s look like?
The mucosal surface of the damaged segment of the gut has a characteristic ‘cobblestone’ appearance resulting from the combination of deep mucosal ulceration and nodular submucosal thickening.
What are some clinical features of CD?
- Diarrhoea (mucus) –>
- Cramps
- Incontinence
- Abdominal pain (due to strictures)
- Post-prandial pain
- Intestinal infections
- Weight loss –> feeling better when not eating
- Chronic perianal symptoms e.g. skin tags and abscesses
- Symptoms of generalised malabsorption –> check blood markers for nutritional status e.g. iron, B12, VD, hydration, electrolytes
- Fistulae
- Gut perforations and abscesses are common
- Low grade fever –> due to the whole intestinal wall being affected which leads to a change in metabolic demands which can causes an increase in temperature
Crohn’s does slightly increase the risk of bowel cancer but not as much as ulcerative colitis
How can CD cause fat malabsorption?
If the ileum is affected, bile reabsorption can be compromised which can result in fat malabsorption
What is the most common reason for surgery?
Small bowel obstruction
- caused by inflammation and oedema in a section of gut already suffering from a stricture
75% of those who have has small bowel resection will have a recurrence within 5 years and further surgery within 15 years
How is Crohn’s disease diagnosed?
Heamatology:
- Erythrocyte sedimentation –> indicates level of imflammation
- White blood cells
- C-reactive protein
Elevated markers indicate inflammation
Biochemistry:
- Albumin –> low levels can be linked to protein malabsorption
Microbiology:
- Stools –> analysis of bacteria as well to identify blood and immune cells
Blood can be found in stools however difficult to see due to the colour from the location of the bleed
Next approach:
Barium radiography (contrast):
- Identify and strictures or fistilations
Endoscopy:
- Identify areas of damage
- Take biopsies for histological examination
- Look for common Crohn’s features such as ‘cobblestone’ lining of gut wall
Physical examination:
- May be useful in some cases
- Matting of bowel sections appears as right palpable mass with pain and tenderness on examination
- If the gut affected is small, this can continue for years before diagnosis is made
Overall:
- Blood test
- Physical examination
- Radiography (occasionally)
- Colonoscopy and/ or endoscopy
- Biopsy
Why does Crohn’s cause more malabsorption than Ulcerative colitis?
Because Crohn’s affects more areas than Ulcerative Colitis. UC on effects colon and rectum whereas crohns effects both small and large intestine which means that if will affect the malabsorption of more nutrients due to more areas being affected.
linked more to malabsorption and malnutrition, weight loss is common
What categories does Crohn’s fall into, in terms of malnutrition?
Dietary intake
Nutrient losses
The absorptive surface area in Crohns may be decreased by
- inflammation of the small and large bowel
- bacterial overgrowth, shift the composition of the microbiome and may be an opportunity for pathogenic bacteria to grow
- multiple bowel resections (surgery)
This may lead to the malabsorption of essential nutrients
Nutrient requirement
How is fat malabsorption related to Crohn’s?
Bile salts (produced in the liver, and stored in the gall bladder) are excreted into the duodenum through bile ducts where they travel to the ileum to aid fat absorption.
When the ileum is affected by Crohn’s the bile salts are not able to be reabsorbed, or at least not as much. Usually, 95% of bile salts are reabsorbed here. The reabsorption of bile salts also includes the absorption of fat and some fat-soluble vitamins, such as A, D, E, K, and B12.
With both less bile salt reabsorption, the fat is unable to be absorbed leaving it to leave via stools.
This in turn leads to fat malabsorption and in some cases deficiency of fat-soluble vitamins, hence why Crohn’s can lead to malnutrition.
Low levels of B12 can lead to anemia due to B12 being required in the synthesis of red blood cells.
What is the treatment/ management of Crohn’s disease?
Management depends upon the clinical status of the patients
Treatment aims
- induce and prolong periods of remission
- reduce inflammation
Nutritional support
- weight gain?
- deficiencies?
Drug therapy
- Oral steroids
- Antibiotics ( reduce bacteria overgrowth)
- Drugs which moderate specific components of the inflammatory response
- Drugs to treat diarrhoea
- Drugs which combat bile salt mediated diarrhoea
Enteral nutrition
- Reduce gut activity to enhance its healing
- Introduce food very slowly and check tolerance
- May be as effective as corticosteroids to manage crohn’s disease at first and to induce remission and should be the main therapeutic option in children
- Helps manage strictures
Surgeries
- Resection in those patients with stricture
- Abscesses and draining fistulae may require surgical repair
How to check if a patient is in remission:
- Analyse general markers related to the condition and symptoms to be monitored to see if there is improvement in the condition from treatments.
- Analyse changes in symptoms
- Check for changes in weight
- Repeat a scan or scopes (usually only happens 1 or 2 years after diagnosis)
What drug therapies are offered to those with Crohn’s?
Oral steroids
- Not recommended for those with diabetes
- Useful
- These drugs reach their site of action before being absorbed and metabolised
- The reduces systemic side effects
- May also be given rectally in those with rectal and sigmoid colon lesions
- Because of their immunosuppressive effects they need to be used carefully in those suffering gross infections
Antibiotics -> reduce bacterial overgrowth
Drugs that:
- moderate specific components of the inflammatory response
- treat diarrhoea
- combat bile salt mediated diarrhoea
Why is enteral/ parenteral nutrition recommended for those with Crohn’s?
It allows the gut to heal and recover whilst giving the patient good nutrition.
Liquid diet –> foods introduced slowly depending on tolerance and permission from the doctor (if their condition is improving)
Helps with stricture management
Reduces intestinal inflammation
