16. Crohns Flashcards
normal functions of the colon
- Salvage of water and electrolytes (Flux)
- Absorption of unabsorbed carbohydrates
- Motility and defecation
- Secretion of mucus
Gut flux: salvage of H20
fluid entering GI tract = 8.5L
fluid absorbed from GI tract = 8.4L
Fluid excreted from GI tract = 100ml
Mucus secretion from colonic mucosa
- Goblet cells
- Found in crypts and surface epithelia
- Lubricates the colon
- Bicarbonate rich, so buffers luminal contents
influence of colonic inflammation on this normal function
inflammatory cells aggregate in crypts → cells release inflammatory cytokines → leads to cell death → mucosal hyperplasia
Haemoglobin
Low
Bleeding into the GI tract from inflammation
ESR
High
Marker of inflammation
CRP
High
Marker of inflammation
Platelets
High
Increased inflammation = Thrombocytosis
Albumin
Low
Inverse marker of inflammation
Inflammation = decreased albumin synthesis
Faecal Calprotectin
High
used to measure how much inflammation is in the GI tract
Crohn’s disease
Affects anywhere from mouth to anus Skip lesions Most common site ileum (50%) Deep ulcers Full thickness inflammation to serosa 10% develop fistulae Fibrous shortening of the intestine Stricturing
Ulcerative Colitis
Only affects the large bowel No skip lesions, continuous inflammation Starts in rectum, extends proximally Horizontal superficial ulcers Mucosal and sub-mucosal inflammation Fistulae rare Muscular shortening of the intestine Stricturing
Corticosteroids – prednisolone, hydrocortisone
Used during a “flare”
suppresses inflammation
bind to Glucocorticoid Receptors
inhibit the expression of genes associated with inflammatory cytokines
Azathioprine and mercaptopurine – a purine analogue
reduces the need for steroids
inhibit an enzyme which is required for the synthesis of DNA
reduces mitosis of lymphocytes
- Biological agents: anti-TNF alpha monoclonal antibody therapy (infliximab, adalimumab)
directly inhibit TNF alpha
reduce inflammation
