What is the recommended treatment for a patient with anemia secondary to induced gastritis?

Treatment of Anemia Secondary to Induced Gastritis

Immediately discontinue oral iron supplementation and switch to intravenous iron therapy, as oral iron can cause direct mucosal injury and gastritis that perpetuates bleeding and anemia. 1

Immediate Management Steps

Discontinue the Causative Agent

• Stop oral iron pills immediately if they are the cause of gastritis, as they can cause corrosive mucosal damage leading to gastrointestinal bleeding and worsening anemia 1
• If the patient is on proton pump inhibitors (PPIs), consider switching to an H2-receptor antagonist (such as ranitidine or famotidine), as PPIs can impair iron absorption and may contribute to iron deficiency anemia 2
• PPIs do not cause iron deficiency anemia directly according to guidelines, but individual case reports suggest they may contribute in susceptible patients 3, 2

Switch to Intravenous Iron

• Initiate IV iron therapy as first-line treatment when active gastritis/inflammation is present, as oral iron is poorly absorbed and can worsen mucosal injury 4, 5
• Ferric carboxymaltose is preferred, allowing 750-1000 mg delivery in a single 15-minute infusion 4
• IV iron demonstrates superior efficacy with an odds ratio of 1.57 for achieving a 2.0 g/dL hemoglobin rise compared to oral iron 5
• Monitor for hypophosphatemia with repeat courses and observe for hypersensitivity reactions during and for 30 minutes after infusion 4

Diagnostic Evaluation

Essential Testing

• Screen for celiac disease with anti-endomysial antibodies and IgA measurement, as 2-3% of patients with iron deficiency anemia have celiac disease 3, 6
• Test for H. pylori infection using noninvasive methods (urea breath test or stool antigen test) after endoscopy, as H. pylori is associated with gastritis and impaired iron absorption 3
• Treatment of H. pylori improves hemoglobin by a mean of 2.2 g/dL (95% CI, 1.3–3 g/dL) and ferritin by 23.2 ng/mL (95% CI, 12.2–34.3 ng/mL) when combined with iron replacement 3
• Consider screening for autoimmune atrophic gastritis in refractory cases by measuring fasting gastrin levels and antiparietal cell antibodies, though routine gastric biopsies are not recommended 3, 7, 8
• Autoimmune atrophic gastritis is found in 27% of patients with unexplained iron deficiency anemia and causes refractoriness to oral iron in 71% of affected patients 7

Endoscopic Evaluation

• Perform bidirectional endoscopy (upper endoscopy and colonoscopy) in postmenopausal women and men with iron deficiency anemia to exclude malignancy and identify sources of bleeding 3
• Look specifically for mucosal erythema, ulceration, and pill debris in the gastric fundus if iron pill gastritis is suspected 1
• The presence of erosive gastritis, peptic ulcer disease, or esophagitis should not deter lower GI investigation until colonoscopy is completed 3

Treatment Protocol

Iron Replacement Strategy

• Target ferritin levels above 100 μg/L in the presence of inflammation, as ferritin is an acute-phase reactant that rises artificially during gastritis 5
• Continue IV iron re-treatment whenever ferritin drops below 100 μg/L given the inflammatory state 5
• Expected hemoglobin rise is approximately 2 g/dL after 3-4 weeks of appropriate IV iron treatment 4, 6

H. pylori Eradication (if positive)

• Triple therapy: Omeprazole 20 mg + amoxicillin 1000 mg + clarithromycin 500 mg, all twice daily for 10 days 9
• Dual therapy alternative: Omeprazole 40 mg once daily + clarithromycin 500 mg three times daily for 14 days 9
• H. pylori eradication in previously refractory IDA patients results in significant hemoglobin increase from 9.4±1.5 to 13.5±1.2 g/dL within 3-6 months 7

Gastric Acid Suppression

• If continuing acid suppression therapy for gastritis healing, use the lowest effective dose 9
• Omeprazole 20 mg once daily for 4-8 weeks is appropriate for active benign gastric ulcer 9
• Consider switching from PPI to H2-receptor antagonist once acute gastritis heals to minimize long-term iron malabsorption risk 2

Monitoring and Follow-up

Short-term Monitoring

• Recheck complete blood count, ferritin, and inflammatory markers (CRP) in 3-4 weeks 5
• If no improvement after 4 weeks, evaluate for non-adherence, ongoing blood loss, or malabsorption 6
• Symptom improvement should begin within 2-4 weeks of IV iron initiation 5

Long-term Monitoring

• Monitor hemoglobin and erythrocyte indices every 3 months for the first year after correction, then again after another year 6
• If anemia does not resolve within 6 months despite appropriate therapy, re-evaluate for ongoing occult blood loss and consider hematology consultation 4, 6
• Full resolution requires 3-6 months of treatment to correct anemia and replenish iron stores completely 5

Critical Pitfalls to Avoid

• Never continue oral iron beyond 4 weeks without documented hemoglobin response—switch to IV iron if no improvement 4
• Do not attribute iron deficiency anemia to aspirin, warfarin, or PPIs until complete GI investigation has been performed 3
• Do not use multiple daily doses of oral iron—once-daily dosing has similar efficacy with better tolerability 4
• Do not assume gastritis or peptic ulcer disease is the sole cause of anemia until both upper and lower GI tracts have been evaluated for malignancy 3
• In patients with atrophic gastritis, also check vitamin B12 levels, as 55% of patients with autoimmune atrophic gastritis have low B12 7