Crohn’s disease and Ulcerative colitis

	Crohn’s Disease	Ulcerative Colitis
Epidemiology	Younger people Smokers – 3-4 times more common Racial preference: Jewish & Caucasian	Younger people Non-smokers – smoking seems protective for UC (many patients with UC may present after smoking cessation)
age	Peak onset: 15-30 years Can also present in children – FFT and also in those in their 60’s	First peak onset 15-25 years (up to age 40 years) Second peak onset > 50 years
Risk factors	Tobacco Abuse Oral Contraceptives Antibiotics Frequent NSAIDs Urban environment1 ^o relative with Inflammatory Bowel Disease Minimal increased Colon Cancer risk (contrast with Ulcerative Colitis)	Specific Bacterial Gastroenteritis infections (Nontyphoid Salmonella, Campylobacter, ,Clostridioides difficile) Family History confers – Monozygotic twin: 95 fold increased risk Higher risk with refined sugar intake and soda intake, increased meat and fat intake
Regions involved	Transmural disease (Granulomas) that may affect any part of the GIT Commonly – Terminal ileum & colon Can affect mouth to anus Skip lesions	Mucosal disease (no Granuloma)confined to the colon Begins at the rectum and Retrograde extension and Continuous Ulcerative Proctitis 🡪 Proctosigmoiditis 🡪 Pancolitis

Clinical presentation	Adult (strongest associations first): Perianal lesions: fistulae Abscesses Strictures Weight loss in 3 months Abdominal pain >3 months Nocturnal diarrhea Fever Abdominal pain subsides for 30-45 minutes after meals No rectal urgency Mass often at the right lower quadrant (common) Obstruction (due to stricture, fistula, or abscess) Child (strongest associations first): Anemia Hematochezia Weight loss Vitamin malabsorption Malnutrition (common) Abdominal distension (common) Extra-intestinal symptoms (common)	Classic: Intermittent bloody diarrhea (most common presenting complaint) Rectal or fecal urgency Tenesmus Abdominal pain (often in the left lower quadrant) Fever Malaise Weight loss Additional features: No vitamin malabsorption (ileum typically not affected) Malnutrition (occasionally) Abdominal distension (if severe) Extra-intestinal symptoms (rare), such as primary sclerosing cholangitis (PSC) and thromboembolic events

Extra-intestinal symptoms	extraintestinal findings are more common with Crohn’s Disease Joints: – migratory polyarthritis (5-21% of cases) – sacroiliitis – ank spon Skin: – erythema nodosum – pyoderma gangrenosa – Clubbing – Psoriasis – Aphthous Stomatitis, Aphthous Ulcers or Canker Sores (4%) Eyes: – Uveitis – episcleritis – iridocyclitis Liver: – Primary Sclerosing Cholangitis (4-5% co-Incidence) – Hepatic Steatosis – Cholelithiasis Autoimmune: – celiac – thyroid Bones : – osteopenia/osteoporosis – osteomalacia Blood : – anaemia Rare (bronchitis, bronchiectasis, other lung disease, hyperhomocysteinemia, pancreatitis, renal stones, thromboembolism, PSC, cholelithiasis, nephrolithiasis)
Investigations	Bloods: – CRP: shown to correlate with clinical, endoscopic and histologic disease activity persistent elevation is associated with a higher relapse rate and better response to infliximab anemia of chronic disease (normocytic, normochromic) – ESR – WCC – hypoalbuminemia – pANCA +ve 🡪 UC – ASCA +ve 🡪 CD Other: – IS, Mg, B12 (absorption issues), LFT & INR, Coeliac Ab Stool cultures: – to r/o infective causes – Faecal Calprotectin Imaging: – AXR: string sign (due to hypertrophy of intestinal wall  narrowing of GIT) – Abdo USS or CT scan (regions of narrowing & dilation) – CT enteroclysis – contrast is infused via a nasogastric tube – MRI – Colonoscopy & biopsy – never perform in acute presentation/ flare 🡪 +++ pain & risk of perforation Barium enema: – cobble stone, rose thorn ulcers, colon strictures & proximal dilation – now rarely used in IBD and has been replaced by colonoscopy
Complications	Obstruction Fistula Perforation Peritonitis Perianal disease – fissures, fistulas, skin tags, ulcers Other: Cancer (but less common than in UC), Malabsorption	Cancer +++ (increased with duration of UC, extent of UC, concurrent PSC, persistent mucosal inflammation, dysplasia Toxic mega colon (rare)

Faecal Calprotectin

Faecal Calprotectin
- Protein complex formed by S100A8 and S100A9, both members of the S100 family of calcium-binding proteins.
- Binds zinc and calcium, enabling structural changes and biological activity.
- Referred to as calprotectin due to its calcium-binding and protective immune functions.
  
  Cellular Origin and Abundance
- Highly abundant in neutrophils, comprising ~60% of total cytosolic protein in these cells.
- Also found in monocytes, macrophages, and epithelial cells, but to a lesser extent.
  
  Role in Inflammation and Immunity
- Released extracellularly during neutrophil activation or cell death.
- Acts as a biomarker of neutrophilic inflammation, particularly in mucosal surfaces like the GI tract.
- Prominent role in diseases like inflammatory bowel disease (IBD) and rheumatic diseases.

Clinical Utility of Faecal Calprotectin

Diagnostic Role

Non-invasive biomarker to differentiate:
- Organic GI disease (e.g., IBD, infections, neoplasia) → elevated levels.
- Functional GI disorders (e.g., IBS) → normal levels.
Helps reduce unnecessary endoscopies.

Monitoring Role

Tracks disease activity in IBD (Crohn’s, ulcerative colitis).
Can help predict relapse and assess mucosal healing.
Useful in therapy response monitoring.

Sample Analysis

Expressed as μg/g of faeces.
Stable in stool samples stored up to 7 days at 2–8°C.

Reference Intervals (Adults)

Concentration	Interpretation
<50 μg/g	IBD unlikely (but not excluded)
50–100 μg/g	Possible IBD or other inflammation (infection, coeliac, diverticulitis)
>100 μg/g	Strongly suggestive of IBD or significant inflammation

Note: Calprotectin increases with age. Use caution interpreting borderline results in elderly.
For individuals under longitudinal follow-up, use patient as their own baseline reference.

Paediatric Considerations

Faecal calprotectin levels are naturally higher in infants and young children.
Neonates and preterms show variable levels (fall then rise post-birth).
Cut-offs in paediatrics not well-established — interpret using serial monitoring over time.
Studies show:
- Age <6 months: much higher baseline calprotectin.
- Gradual decline with age; by ~4 years, levels begin to approximate adult RIs.

Conditions Associated with Elevated Faecal Calprotectin

Inflammatory	Infective/Malignancy	Drug-induced
IBD (Crohn’s, UC)	GI infections	NSAIDs
Coeliac disease	GI malignancy	Proton pump inhibitors
Diverticular disease
Necrotising enterocolitis

Sensitivity and specificity are increased when combined with CRP.

Limitations

Not IBD-specific — elevated in many inflammatory and non-inflammatory conditions.
Mild elevations can be non-specific.
False positives: NSAIDs, PPIs, infections.
Must be interpreted in clinical context.

Clinical Summary

Safe, reliable, and non-invasive tool in gastroenterology.
Particularly valuable for:
- Triage of diarrhoeal illness.
- Monitoring IBD.
- Minimising invasive investigations when appropriate.
Must be interpreted with patient history, other labs, and imaging findings.

MBS as of 1 November 2021

MBS Item 66522 – Initial Faecal Calprotectin Test

Initial assessment for inflammatory bowel disease (IBD) in patients with persistent gastrointestinal symptoms.

Eligibility Criteria (All must apply):

Patient is <50 years of age.
Has gastrointestinal symptoms suggestive of IBD or functional bowel disease for >6 weeks.
Infectious causes have been excluded.
Likelihood of malignancy is low.
No clinical alarm features present (e.g. GI bleeding, weight loss, anaemia, family history of CRC).

Notes:

Only one rebateable test under this item unless criteria for 66523 are met.
Aimed at reducing unnecessary endoscopy referrals in younger patients.

MBS Item 66523 – Follow-up Faecal Calprotectin Test

Purpose:
Second-line test when the result of item 66522 is inconclusive (50–100 μg/g).