Review Question - QID 104681

This patient has microcytic anemia and a history of chronic NSAID use. His anemia is most likely due to iron deficiency from a chronic upper gastrointestinal (GI) bleed.

Iron deficiency anemia is the most common anemia worldwide. Risk factors include colon cancer, menstruation, pregnancy and lactation, dietary deficiency, and GI blood loss secondary to chronic NSAID use. NSAIDs inhibit the COX-1 and COX-2 enzymes, preventing the production of prostaglandins and leading to increased gastric acid secretion and decreased secretion of protective mucus and bicarbonate. Erosion and ulceration of the gastric mucosa results, leading to acute or chronic upper GI bleeding.

Mitchell at al. review occult and obscure gastrointestinal bleeding, noting that it is usually discovered upon a positive fecal occult blood test or when iron deficiency anemia is detected. The initial workup typically includes colonoscopy and esophagogastroduodenoscopy (EGD). Treatment involves stopping any offending agents, endoscopic ablation of the bleeding site, or angiographic embolization if necessary.

Wallace reviews the mechanisms, prevention, and clinical implications of NSAID induced damage to the small intestine. The author states that injury and associated bleeding of the small intestine is more commonly associated with NSAID use than is injury to the stomach. In addition, proton pump inhibitors used to protect the gastric mucosa can actually worsen NSAID induced damage to the small intestine. Studies in animal models are revealing a highly complex pathogenesis, but trials of novel NSAIDs in these models offer hope for a solution to this adverse effect.

Illustration A is a diagram demonstrating how NSAIDs interfere with the protective mechanisms of the GI tract.

Incorrect Answers:
Answers 1, 2, 4,and 5 could all cause anemia, but none of these is more likely given the patient's history of chronic NSAID use and age.