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EXTRA Q02. Iron-deficiency anaemia, weight loss and positive occult blood in an older patient require? A. Colonoscopy with biopsy B. Upper GI manometry C. Serum lipase D. Thyroid scan E. HIDA scan

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"iron deficiency anemia"[MeSH Terms] AND "colonoscopy"[MeSH Terms]

Answer: A. Colonoscopy with biopsy
An older patient with iron-deficiency anaemia, weight loss and a positive faecal occult blood test has gastrointestinal blood loss until proven otherwise. Colorectal cancer, especially right-sided, is the main concern. Weight loss makes malignancy more likely. Colonoscopy lets you see the lesion and biopsy it.
  • Iron deficiency plus occult blood points to chronic GI bleeding. Goldman-Cecil says chronic occult bleeding can cause iron-deficiency anaemia, and that both upper endoscopy and colonoscopy should be done to look for a source. - Goldman-Cecil Medicine, Gastrointestinal bleeding
  • Harrison's says a positive faecal occult blood test needs colonoscopy. - Harrison's Principles of Internal Medicine 22E, Positive Fecal Occult Blood Test
  • Colon neoplasms bleed intermittently, so occult bleeding is often their only sign. - Schwartz's Principles of Surgery, 11th Ed
  • Symptom to Diagnosis notes that many experts recommend evaluating the whole GI tract when iron deficiency is present. Colonoscopy alone is enough only when the occult blood is positive and there is no iron deficiency. - Symptom to Diagnosis, 4th Ed, Evidence-Based Diagnosis
If colonoscopy is negative, the next step is upper endoscopy (EGD), then small-bowel evaluation such as capsule endoscopy.
Why the other options are wrong:
  • B. Upper GI manometry tests motility disorders such as achalasia. It doesn't look for a bleeding source.
  • C. Serum lipase is for pancreatitis.
  • D. Thyroid scan is for thyroid nodules or hyperthyroidism.
  • E. HIDA scan is for biliary disease such as cholecystitis or biliary dyskinesia.
A recent search of the last two years of meta-analyses found nothing that contradicts this. A 2024 meta-analysis (PMID 38977142) found that faecal immunochemical tests can improve colonoscopy triage in iron deficiency. It doesn't change the answer for a patient who already has weight loss and a positive occult blood test.
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