GASTROINTESTINAL Flashcards
What is it inflammatory bowel disease? What is seen in it?
It’s umbrella term for two main diseases causing inflammation of the GI tract: Ulcerative Colitis and Crohn’s disease.
Mucosal immune system exerts an inappropriate response to luminal antigens (such as bacteria)
which may enter the mucosa via a leaky epithelium
causes fibrous cobblestone scarring
Outline the epidemiology behind Crohn’s disease
Highest incidence and prevalence in Northern Europe, UK and North America
F>M
Presents mostly at 20-40
Where does Crohn’s affect? Where does it most commonly affect?
Affects any part of gut from mouth to anus – commonly ileum and colon
What genetic mutations have been seen to cause Crohns?
CARD15/NOD2 mutation
What pathogens can cause Crohn’s?
Escherichia coli, Mycobacterium avium paratuberculosis, C.Difficile
What are some risk factors for Crohns
- Family history
- Smoking
- NSAIDs may exacerbate
- Stress and depression
Outline the pathophysiology behind Crohn’s
A foreign pathogen triggers the immune system, which are able to get through the gut wall due a defect in the epithelium
This triggers a large and uncontrolled immune response - These immune cells invade deep into the mucosa and organise themselves into granulomas
This leads to ulcers forming throughout all layers, hence Crohn’s being said to be transmural, and cobblestone in appearence
the ileum is the most commonly affected site of crohns
Pathophysiology behind Crohn’s what are immune cells seen in it? In what way are the ulcers arranged at what is this called?
What is the most commonly affected site in Crohns?
T helper cells release cytokines which attract cells such as macrophages which release substances like proteases, platelet activating factor and free radicals
Ulcers occurs in patches known as skip lesions
the ileum is the most commonly affected site of crohns
Normal physiology - what are the layers of the GI tract?
Mucosa
Submucosa
Muscularis Externa
Serosa
(mostly, Sam Makes Eleanor Sick)
picture - taken from macmillan.org
How can Crohn’s lead to
a) Blood in Stool
b) Malabsorption
Blood may appear in stools due to damaged intestinal walls and due to the damage, the intestines lose their ability to absorb water, causing diarrhoea.
If the small intestine is affected, it loses its ability to absorb nutrients, leading to malabsorption.
What are the signs of Crohn’s?
Abdominal tenderness
Fever
Mouth ulcers
Rectal examination will show blood, skin tags, fissures and fistulas
eye problems - uveitis
What are the symptoms of Crohn’s?
Weight loss
Diarrhoea
Abdominal pain (most common in RLQ where the ileum is)
Lethargy and malaise also symptom
What are some first line investigations for Crohn’s?
Faecal calprotectin (released by intestines when inflamed)
C-reactive protein is a good indication of current inflammation
FBC:leukocytosis during a flare;anaemia due to vitamin B12, folate or iron deficiency
Stool sample to rule out infectious diseases
- U&Es: to assess for electrolyte disturbance and signs of dehydration
- Coeliac serology: to exclude coeliac disease
What is the gold standard test of Crohn’s?
What would you see, and what would you see with a biospy?
Colonoscopy will show mucosal inflammation (deep ulcers, skip lesions and cobblestone appearance)
Histology will show transmural inflammation with granulomas and increased number of goblet cells
What are some first line treatment options for Crohns?
Oral corticosteroids e.g. budesonide and prednisolone, as well as an elemental diet - pre-digested nutrients
What are some second line treatments to consider in Crohns, and what would you give in flairups?
IV hydrocortisone in severe flare ups
Add anti-TNF antibodies e.g. Infliximab if no improvement
Consider adding other immunosuppressive drugs
Surgery – doesn’t cure disease
What are some immunosuppressants used to treat Crohn’s?
azathioprine or methotrexate to remain in remission if there are frequent exacerbations.
Thiopurine methyltransferase level should be measured before using
Name some complications of Crohns.
- Peri-anal abscess:
- Anal fissure:a small tear in the lining of the anus
- Anal fistula:an abnormal connection between 2 epithelial surfaces, e.g. from the anal canal to skin surface
- Strictures and obstruction:
- Perforation:chronic inflammation can weaken the bowel wall and predispose to subsequent perforation
- Malignancy: colorectal cancer and small bowel cancer
- Osteoporosis
- Anaemia and malnutrition
What are the key things to remember for Crohn’s?
NESTS
N- No blood or mucus
E- entire GI tract
S- Skip lesions
T- Terminal ileum and transmural
S- Smoking is a big risk factor
What is Ulcerative colitis?
A type of IBD that typically involves the rectum and variable lengths of the colon. Will never spread beyond the ileocecal valve, and does not affect the anus
What age groups/races to ulcerative colitis effect the most?
bimodal age distribution, 15-25 and 55-70 years of age.
- Highest incidence and prevalence in Northern Europe, UK and North America
- Affects caucasians and eastern European Jews most
What are some risk factors (including genes) for getting ulcerative colitis?
- Family history
- HLA-B27 gene - codes for a protein assossicaated with autoimmune conditions like UC
- Caucasian
- Non-smoker
- NSAIDs- associated with flares
- Chronic stress and depression - associated with flares
picture taken from netters illustrated human pathology
Outline pathophysiology behind ulcerative colitis?
High levels of what substance is thought to correlate with exacerbations
Not well understood, however thought to be Autoimmune
Bacteria/dietary antigens pass into lamina propria
Picked up by antigen presenting cells, in lamina propria
Cytotoxic T cells destroy the epithelial lining of the colon, leaving behind ulcers.
UC seen more in people with higher sulphide producing bacteria ==> often high sulphide production is correlated with periods of active inflammation
What antibodies are found in patients with UC?
Antibodies found - p-ANCAs - Perinuclear antineutrophilic cytoplasmic antibodies.
just remember anti neutrophilic antibodies
antibodies that target antigens in the body’s own neutrophil
Maybe party due to immune reaction to gut bacteria that have to structural similarity to own neutrophils == cross react.