What is the appropriate intervention for a patient with iron deficiency anemia, as indicated by low iron saturation and ferritin levels?

Iron Deficiency Anemia Requiring Iron Supplementation

This patient has clear iron deficiency anemia (hemoglobin 11.9 g/dL with ferritin 10 ng/mL and transferrin saturation 9%) and requires immediate iron supplementation, with oral iron as first-line therapy given the mild anemia and absence of information suggesting active inflammation or intolerance. 1

Diagnostic Confirmation

Your patient meets diagnostic criteria for iron deficiency anemia:

• Hemoglobin 11.9 g/dL is below the threshold of 12 g/dL for women (or 13 g/dL for men) 1
• Ferritin 10 ng/mL is well below the diagnostic threshold of <30-45 ng/mL for iron deficiency 1, 2
• Transferrin saturation 9% is markedly reduced (normal >20%), confirming depleted iron stores 1
• B12 1617 is elevated/normal, ruling out B12 deficiency as a cause 2

Immediate Treatment Approach

First-Line: Oral Iron Supplementation

Initiate oral ferrous sulfate 325 mg on alternate days (or daily if alternate-day dosing is not tolerated), as this is the recommended first-line therapy for mild iron deficiency anemia without active inflammatory disease. 1, 2, 3

• Alternate-day dosing (every other day) improves iron absorption and reduces gastrointestinal side effects compared to daily dosing 2, 3
• If daily dosing is preferred, give 100-200 mg elemental iron per day in divided doses 1
• Take with vitamin C or on an empty stomach to enhance absorption; avoid tea, coffee, or calcium supplements within 2 hours 1, 4
• Common side effects include constipation, nausea, and diarrhea—taking with meals can minimize these 4

When to Consider Intravenous Iron Instead

Switch to intravenous iron if any of the following apply:

• Hemoglobin <10 g/dL (100 g/L) 1
• Active inflammatory bowel disease or chronic inflammatory conditions 1, 3
• Previous intolerance to oral iron 1
• Malabsorption disorders (celiac disease, post-bariatric surgery, atrophic gastritis) 2, 3
• Ongoing blood loss that cannot be controlled 3
• Heart failure (where IV iron improves exercise capacity) 2, 3
• Pregnancy (second or third trimester) 3
• Need for rapid correction 1, 3

Evaluation for Underlying Cause

Investigate the source of iron deficiency based on patient demographics:

For Premenopausal Women:

• Assess for heavy menstrual bleeding as the likely cause 2, 3
• If heavy menses is present, treat the bleeding and provide iron supplementation 1
• Consider non-invasive testing for H. pylori and celiac disease 1
• Reserve bidirectional endoscopy for those with gastrointestinal symptoms or inadequate response to treatment 1

For Men and Postmenopausal Women:

• Perform bidirectional endoscopy (upper and lower) as gastrointestinal bleeding accounts for 94% of cases in this population 1, 2, 5
• Test for H. pylori infection and celiac disease non-invasively before endoscopy 1
• Evaluate for occult gastrointestinal malignancy 1, 5

Additional Considerations:

• Review medications: NSAIDs, anticoagulants, antiplatelet agents 3
• Assess dietary intake, particularly in vegetarians/vegans 1, 3
• Consider atrophic gastritis (autoimmune or H. pylori-related) 3, 6

Monitoring Response to Treatment

Reassess hemoglobin and iron studies in 2-4 weeks after initiating oral iron: 2, 3

• Expected response: Hemoglobin increase of 1-2 g/dL within 4 weeks 1, 2
• If no response after 4 weeks, consider:
  • Non-adherence (50% of patients discontinue due to side effects) 2
  • Ongoing blood loss 3
  • Malabsorption 3
  • Incorrect diagnosis 2

If inadequate response to oral iron, switch to intravenous iron (ferric carboxymaltose, iron sucrose, or low-molecular-weight iron dextran). 1, 3

Treatment Goals

• Correct anemia: Normalize hemoglobin to >12 g/dL (women) or >13 g/dL (men) 1
• Replenish iron stores: Target ferritin >100 ng/mL 1
• Continue iron supplementation for 3-6 months after hemoglobin normalizes to fully restore iron stores 1, 5

Common Pitfalls to Avoid

• Do not screen asymptomatic men or postmenopausal women—but once diagnosed, always investigate the cause 5
• Do not assume menstruation is the sole cause in premenopausal women with severe anemia or gastrointestinal symptoms 1
• Do not give oral iron within 2 hours of antibiotics as it interferes with absorption 4
• Do not exceed recommended dosing—higher doses do not improve absorption and increase side effects 4, 2
• Ferritin can be falsely elevated in inflammatory states; use transferrin saturation <20% as an additional marker in these cases 1