Malabsorption and Small Bowel Disease — Viva Defence

Long case viva — coeliac disease with dermatitis herpetiformis

Candidate's opening statement (SASPOP)

"Doctor, my patient is a 42-year-old woman presenting with coeliac disease. Her problems are: iron deficiency anaemia from proximal small bowel malabsorption (haemoglobin 88, MCV 71, ferritin 4); a 6-kilogram weight loss over 8 months with chronic loose stools; dermatitis herpetiformis on her extensor surfaces; and probable osteoporosis from chronic calcium and vitamin D malabsorption, to be confirmed on DEXA. The diagnosis is confirmed by positive anti-tTG IgA at 14 times the upper limit of normal, positive anti-endomysial antibody, normal total IgA (excluding selective IgA deficiency), and Marsh 3c total villous atrophy on duodenal biopsy. The treatment is a lifelong strict gluten-free diet with nutritional and bone assessment, and dapsone for the dermatitis herpetiformis while the diet takes effect." ^[1]

Problem list

1. Coeliac disease (Marsh 3c) — confirmed by serology and histology.
2. Iron deficiency anaemia (proximal small bowel malabsorption).
3. Dermatitis herpetiformis (cutaneous manifestation of coeliac disease).
4. Probable osteoporosis (chronic calcium and vitamin D malabsorption) — DEXA pending.
5. Nutritional deficiency — weight loss, possible folate and fat-soluble vitamin deficiency. ^[1]

Integrated management plan

The gluten-free diet. A lifelong strict gluten-free diet excluding wheat, barley, and rye is the only treatment. Oats may be introduced cautiously. Dietitian referral for education on label reading, hidden gluten, and cross-contamination. Monitor anti-tTG IgA response (should normalise over 6 to 12 months) ^[1].

Nutritional correction. Iron replacement (oral or intravenous if intolerant), folate, calcium, vitamin D, and fat-soluble vitamins as guided by levels. ^[1]

Bone health. DEXA scan at diagnosis. Calcium and vitamin D supplementation, with a bisphosphonate if osteoporotic. ^[1]

Dermatitis herpetiformis. Dapsone provides rapid control of the rash and pruritus within days by inhibiting neutrophil recruitment, used as a bridge while the gluten-free diet takes effect over months. G6PD must be checked before starting dapsone because of the risk of haemolysis ^[1].

Vaccination. Pneumococcal and influenza vaccination for hyposplenism-associated infection risk. ^[1]

Family screening. First-degree relatives carry a 10 per cent risk and should be tested by serology. ^[1]

Surveillance. Annual review with antibody monitoring, DEXA as indicated, and education on alarm symptoms (new weight loss, worsening diarrhoea, abdominal pain) that would prompt investigation for refractory disease or lymphoma. ^[1]

Examiner probing questions

Examiner: "Why did this patient present with microcytic rather than macrocytic anaemia?" Because iron is absorbed predominantly in the duodenum and proximal jejunum, which are the sites most affected by coeliac enteropathy. Microcytic iron deficiency is therefore the expected haematological pattern and is in fact the single most common adult presentation. Macrocytic anaemia from B12 or folate deficiency would suggest terminal ileum disease (B12) or more diffuse mucosal involvement (folate). The type of anaemia is the single most powerful bedside localiser in the malabsorption workup. ^[1]

Examiner: "What is the significance of checking total serum IgA alongside the anti-tTG IgA?" Selective IgA deficiency is 10 to 40 times more common in coeliac disease than in the general population. Because anti-tTG IgA and anti-endomysial IgA are IgA-class antibodies, an IgA-deficient patient produces a false-negative serological result. The total IgA must always be checked; if low, IgG-based alternatives (anti-tTG IgG or anti-DGP IgG) should be used. This patient's total IgA was normal at 1.2 grams per litre, so the anti-tTG IgA result is reliable ^[1].

Examiner: "What would make you concerned about refractory coeliac disease, and how do you classify it?" Persistent or recurrent malabsorptive symptoms with villous atrophy despite a strict gluten-free diet for over 12 months would raise concern — but first I would always exclude inadvertent gluten ingestion (the most common cause of non-response) by dietitian review and anti-tTG monitoring. Other causes of villous atrophy (tropical sprue, common variable immunodeficiency, olmesartan enteropathy, SIBO) must also be excluded. Refractory disease is then classified by intraepithelial lymphocyte phenotyping and T-cell clonality into type 1 (normal phenotype, low lymphoma risk, responds to budesonide) and type 2 (aberrant clonal IELs, 30 to 50 per cent risk of EATL over 5 years, requires specialist centre management) ^[3].