Anaemia — Systematic Workup: Written Clinical Reasoning

SAQ 1 — Integrated Anaemia Workup and Management (20 marks, 30 minutes)

Prompt: Classify this patient's anaemia, interpret the iron studies, construct a prioritised problem list, and outline an integrated investigation and management plan with justification for each decision. ^[1]

Model Answer

Classification and interpretation of results (5 marks): ^[1]

1. Anaemia, microcytic (MCV 71 fL), hypochromic — the morphological bucket is microcytic, which immediately narrows the differential to iron deficiency, thalassaemia trait, anaemia of chronic disease, sideroblastic anaemia, or lead poisoning.
2. The iron studies confirm iron deficiency. Ferritin is 6 micrograms per litre (markedly low, well below the threshold of 30 for uncomplicated deficiency), transferrin is high at 4.1 g/L (the body upregulates transferrin in iron deficiency), and the transferrin saturation is 7 per cent (critically low). This is the classic iron deficiency pattern and the opposite of anaemia of chronic disease (which would have a normal or high ferritin and a low transferrin).
3. The reticulocyte count is low (1.0 per cent), confirming that the marrow is not responding — consistent with iron-deficient erythropoiesis, not haemolysis or recovery.
4. The CRP is normal (8 mg/L), so the ferritin of 6 is not falsely normalised by inflammation — this is uncomplicated iron deficiency.
5. The clinical context — dark stools positive for occult blood, weight loss, daily NSAID use — points to a gastrointestinal source of blood loss. The daily ibuprofen raises the possibility of an NSAID-induced gastroduodenal ulcer, but the weight loss mandates exclusion of colorectal or gastric malignancy. ^[1]

Problem list (3 marks): ^[1]

1. Severe iron deficiency anaemia (Hb 76 g/L) from chronic gastrointestinal blood loss — symptomatic, with exertional dyspnoea.
2. Likely gastrointestinal pathology — possible malignancy. Weight loss and occult blood in a 68-year-old man mandate urgent endoscopic investigation for gastric or colorectal cancer.
3. NSAID-related gastrointestinal bleeding — daily ibuprofen may be causing or contributing to a gastroduodenal erosion or ulcer.
4. Iatrogenic contribution — the ibuprofen should be ceased immediately. ^[1]

Investigation plan (5 marks): ^[1]

1. Urgent coeliac serology — anti-tissue transglutaminase IgA plus total IgA to exclude IgA deficiency. Coeliac disease is a common, treatable and easily missed cause of iron deficiency in adults ^[1].
2. Urgent oesophagogastroduodenoscopy (OGD) — to identify gastritis, peptic ulcer disease, gastric cancer, or the villous atrophy of coeliac disease (duodenal biopsies taken even if the mucosa appears normal).
3. Urgent colonoscopy — to identify colorectal cancer (the weight loss and occult blood make this the most dangerous possibility), polyps, or inflammatory bowel disease.
4. If both OGD and colonoscopy are negative, capsule endoscopy to examine the small bowel for angiodysplasia, Crohn's disease, or small bowel tumour.
5. Repeat FBC and iron studies after starting iron to confirm a reticulocyte response within 7 to 10 days and a haemoglobin rise of about 20 g/L over three weeks.

Management plan (5 marks): ^[1]

1. Stop the ibuprofen immediately and advise paracetamol-based analgesia. If an NSAID is essential, add a proton pump inhibitor or use a COX-2 selective agent.
2. Start oral iron replacement — ferrous sulfate 200 mg three times daily (or every other day to improve tolerance and absorption), for a minimum of three months to correct the haemoglobin and replete iron stores. Counsel on side effects (constipation, dark stools, nausea) and the expected timeline of response.
3. Urgent gastroenterology referral for OGD and colonoscopy — within two weeks given the suspicion of malignancy. The iron studies confirm the deficiency; the endoscopies find the cause ^[1].
4. Transfusion is not indicated at this time. The patient is chronically anaemic (not acute), is haemodynamically stable, and has no ischaemic features. The restrictive transfusion threshold of 70 g/L in a stable patient applies, and this patient's Hb of 76 g/L does not meet it — treating the iron deficiency is the correct approach. If he develops ischaemic chest pain or heart failure, transfuse a single unit at a time with diuretic cover ^[4].
5. Longitudinal follow-up: after GI management and iron repletion, recheck the FBC and ferritin at three months to confirm correction. If the iron deficiency recurs despite adequate iron and a negative initial workup, reassess for ongoing occult blood loss.

Communication and safety (2 marks): Explain to the patient that his anaemia is from iron loss in the bowel, that the ibuprofen is a likely contributor but the weight loss means a thorough search for a more serious cause is essential, and that the endoscopies will find and, if possible, treat the source. Document the discussion about stopping NSAIDs and the plan for urgent endoscopy. ^[1]