What is the recommended treatment for a patient with iron deficiency anemia, given laboratory values of low total iron, low percent saturation, and low ferritin?

Iron Deficiency Anemia Treatment

Start oral iron supplementation immediately with ferrous sulfate 200-325 mg daily (or every other day for better absorption and tolerability), continue for 3 months after hemoglobin normalizes to replenish iron stores, and simultaneously investigate the underlying cause of blood loss. 1

Diagnostic Confirmation

Your laboratory values confirm iron deficiency anemia:

• Ferritin 31 ng/mL is below the diagnostic threshold of 45 ng/mL, confirming depleted iron stores 1
• Transferrin saturation 9% (well below 20%) further confirms absolute iron deficiency 1, 2
• Total iron 39 mcg/dL is markedly low, consistent with severe depletion 1

These values indicate absolute iron deficiency requiring both treatment and investigation of the underlying cause. 1, 3

Immediate Treatment Approach

Oral Iron Therapy (First-Line)

Ferrous sulfate 200-325 mg once daily is the most cost-effective first-line treatment. 1, 4

• Each 325 mg tablet contains 65 mg elemental iron 4
• Alternative dosing: Every-other-day administration improves absorption and reduces gastrointestinal side effects by approximately 50% 3, 2
• Alternative formulations (ferrous gluconate, ferrous fumarate) are equally effective if ferrous sulfate is not tolerated 1
• Adding ascorbic acid (vitamin C) enhances iron absorption when response is suboptimal 1

Expected Response Timeline

• Check hemoglobin in 2-4 weeks: Expect a rise of 1-2 g/dL if treatment is effective 1, 3, 5
• A hemoglobin rise ≥10 g/L within 2 weeks confirms absolute iron deficiency even if initial iron studies were equivocal 1
• Continue iron for 3 months after hemoglobin normalizes to fully replenish iron stores (target ferritin >100 ng/mL) 1

When Oral Iron Fails

Switch to intravenous iron if: 1, 3, 2

• No hemoglobin rise after 3-4 weeks of oral therapy
• Intolerance to at least two different oral iron preparations
• Ongoing blood loss exceeds oral iron absorption
• Malabsorption conditions present (celiac disease, inflammatory bowel disease, post-bariatric surgery)
• Patient has heart failure (IV iron improves exercise capacity) 2

IV iron dose: 1000 mg total dose (given as single or divided doses per product labeling) 1

Mandatory Investigation for Underlying Cause

Recurrent blood loss accounts for 94% of iron deficiency anemia cases and must be identified. 3

For Men and Postmenopausal Women

Perform bidirectional endoscopy (upper and lower) as the primary investigation. 1, 3

• This is a strong recommendation because gastrointestinal malignancy is found in 9% of patients over 65 years with iron deficiency anemia 5
• Before endoscopy: Non-invasive testing for H. pylori and celiac disease (both common, treatable causes) 1
• Reserve endoscopic biopsies for H. pylori/celiac only if non-invasive tests are positive or endoscopic abnormalities are seen 1

For Premenopausal Women

The approach depends on age and clinical context: 1

• Women >45 years: Investigate with bidirectional endoscopy as above (increasing cancer risk with age) 1
• Younger women with obvious menorrhagia: Initial empiric iron supplementation is reasonable, especially if they prioritize avoiding endoscopy risks 1
• However: If iron supplementation fails to maintain normal hemoglobin/ferritin after initial correction, proceed to full gastrointestinal evaluation 1

Additional Testing

• Check for hematuria to exclude urinary tract sources (rare but important) 1
• Hemoglobin electrophoresis if microcytosis persists despite iron repletion (to exclude thalassemia) 1

Follow-Up Monitoring

After hemoglobin normalizes: 1

• Monitor hemoglobin and MCV every 3 months for 1 year, then again at 2 years
• Recheck ferritin if hemoglobin or MCV falls below normal
• Resume oral iron if deficiency recurs
• Further investigation only needed if hemoglobin cannot be maintained with iron supplementation

Critical Pitfalls to Avoid

• Do not rely on ferritin alone in inflammatory conditions: Ferritin is an acute-phase reactant and can be falsely normal up to 100-150 ng/mL in the presence of inflammation 1
• Do not skip investigation in men or postmenopausal women: Empiric iron without endoscopy risks missing gastrointestinal malignancy 1, 5
• Do not stop iron too early: Continue for 3 months after anemia correction to replenish stores, or deficiency will rapidly recur 1
• Do not perform fecal occult blood testing: It is insensitive and non-specific, adding no diagnostic value 1