Why can anemia still occur in gastric ulcers with intermittent bleeding and insignificant blood loss?

Anemia in Gastric Ulcers with Intermittent Bleeding

Anemia can develop in gastric ulcers with intermittent bleeding even when blood loss appears insignificant because chronic occult blood loss depletes iron stores over time, leading to iron deficiency anemia despite the absence of visible bleeding.

Mechanisms of Anemia in Gastric Ulcers with Intermittent Bleeding

1. Chronic Occult Blood Loss

• Even when bleeding is intermittent and appears insignificant, small amounts of blood loss over time can lead to iron deficiency anemia 1
• According to the British Society of Gastroenterology guidelines, occult GI blood loss is a common cause of iron deficiency anemia in adults 1
• The cumulative effect of minimal but persistent blood loss can deplete iron stores before clinical symptoms become apparent

2. Impaired Iron Absorption

• Gastric acid is essential for optimal iron absorption by:
  • Releasing iron from dietary nutrients
  • Converting ferric iron (Fe³⁺) to the more absorbable ferrous form (Fe²⁺)
  • Enhancing iron solubilization at low pH (<3) 1
• Patients with gastric ulcers often have:
  • Reduced gastric acid production due to inflammation
  • Use of acid-suppressing medications (PPIs, H2 blockers) as part of treatment
  • Potential gastric atrophy in chronic cases

3. Inflammation-Related Mechanisms

• Chronic inflammation from ulcers can lead to:
  • Increased hepcidin production, which blocks iron absorption in the intestine
  • Sequestration of iron in macrophages
  • Reduced erythropoiesis
• These mechanisms contribute to anemia of chronic disease that may coexist with iron deficiency 2

Clinical Presentation and Diagnosis

Diagnostic Criteria for Iron Deficiency Anemia

• Serum ferritin <30 μg/L (without inflammation) or <100 μg/L (with inflammation) 2
• Transferrin saturation <20% has high sensitivity for diagnosing iron deficiency 2
• Microcytosis (low MCV) and elevated RDW are characteristic but may be absent in combined deficiencies 1

Common Presentations

• Patients may present with:
  • Fatigue and weakness
  • Pallor
  • Occult blood in stool
  • No overt hematemesis or melena despite ongoing anemia

Management Approach

Diagnostic Evaluation

• Upper GI endoscopy is essential to identify gastric ulcers and assess for active bleeding 1
• Colonoscopy should be considered to exclude lower GI sources of bleeding, especially in men and post-menopausal women 1
• Small bowel evaluation may be necessary if no source is found on bidirectional endoscopy in cases of severe or persistent anemia 1

Treatment Strategy

1. Treat the underlying gastric ulcer:

   • Eradicate H. pylori if present
   • Discontinue NSAIDs if applicable
   • Provide appropriate acid suppression therapy

2. Iron replacement therapy:

   • Oral iron: Ferrous sulfate 200 mg once daily (providing ~65 mg elemental iron) 2
   • Continue treatment for 3 months after normalization of hemoglobin to replenish iron stores 2
   • Consider IV iron if oral iron is ineffective, poorly tolerated, or if there is severe anemia (Hb <10 g/dL) 2

3. Monitor response:

   • Check hemoglobin after 3-4 weeks of therapy (should rise by ~2 g/dL)
   • Complete follow-up iron studies after 8-10 weeks of treatment 2
   • Monitor for recurrence every 3 months for at least a year after successful treatment 2

Special Considerations and Pitfalls

Commonly Overlooked Causes

• Cameron lesions (linear erosions in hiatal hernias) can cause chronic blood loss and anemia 3
• Anastomotic ulcers in patients with prior gastric surgery 4
• Gastric antral vascular ectasia (GAVE) can cause chronic GI bleeding and anemia 5

Important Caveats

• Even with successful treatment of gastric ulcers, iron deficiency anemia may persist if iron stores are not adequately replenished
• Malabsorption of iron may occur in post-gastrectomy patients, requiring parenteral iron administration 6
• Recurrent or refractory anemia despite healing of visible ulcers warrants investigation for other sources of blood loss or malabsorption 7

By understanding these mechanisms, clinicians can appropriately diagnose and manage anemia in patients with gastric ulcers, even when overt bleeding is not apparent.