What is the best course of treatment for a patient with iron deficiency anemia, hypoferritinemia, and low hemoglobin, with laboratory results indicating severe iron deficiency and anemia?

Treatment of Severe Iron Deficiency Anemia

Begin oral iron supplementation immediately with 65 mg of elemental iron daily (ferrous sulfate 325 mg), and simultaneously initiate diagnostic workup to identify the underlying cause of blood loss or malabsorption. 1

Immediate Iron Replacement Therapy

Oral Iron as First-Line Treatment

• Start with oral ferrous sulfate 325 mg daily (65 mg elemental iron), or consider alternate-day dosing if gastrointestinal side effects occur. 1, 2
• Oral iron provides 362% of the U.S. recommended daily intake and should be the initial approach unless specific contraindications exist. 2
• With your ferritin of 5 µg/L and transferrin saturation of 0.03, oral iron absorption should be adequate in the absence of inflammatory conditions or malabsorption. 1
• Reassess hemoglobin after 4 weeks; expect an increase of ≥1.0 g/dL if treatment is effective. 1

When to Use Intravenous Iron

Consider intravenous iron if oral therapy fails after 4 weeks, or if you identify malabsorption, ongoing severe bleeding, or intolerance to oral preparations. 1

• IV iron is indicated when hemoglobin does not increase by ≥1.0 g/dL after 4 weeks of compliant oral therapy. 1
• Total IV iron dose can be calculated using the Ganzoni formula or empirically give 1 gram total, with reassessment afterward. 1
• Regularly-scheduled iron infusions may be needed if chronic bleeding cannot be halted. 1

Mandatory Diagnostic Workup

Essential Testing to Identify the Source

All patients with your laboratory profile require bidirectional endoscopy (upper and lower GI) and celiac disease screening, regardless of symptoms. 1

• Screen for celiac disease with serology (tissue transglutaminase antibody) before endoscopy. 1
• Test for H. pylori non-invasively (stool antigen or urea breath test). 1
• If either test is positive, treat the condition before proceeding with endoscopy. 1

Bidirectional Endoscopy Indications

• With hemoglobin of 100 g/L, ferritin of 5 µg/L, and your degree of iron deficiency, bidirectional endoscopy is strongly recommended. 1
• This applies to all men and postmenopausal women (strong recommendation, moderate quality evidence). 1
• For premenopausal women, endoscopy is conditionally recommended, but those who are younger with plausible menstrual causes may reasonably defer initial endoscopy in favor of empiric iron supplementation. 1
• Only advanced gastric cancer or confirmed celiac disease on upper endoscopy should deter lower GI investigation. 1

Additional Considerations

• Perform urinalysis to exclude urinary blood loss. 1
• In patients over 50 or with marked anemia (your hemoglobin of 100 g/L qualifies), proceed with lower GI investigation even if celiac disease is found. 1
• Avoid routine gastric or small bowel biopsies unless serologies are positive or endoscopic abnormalities are present. 1

Treatment Duration and Monitoring

Replenishing Iron Stores

• Continue iron supplementation for 2-3 months after hemoglobin normalizes to replenish body stores. 1
• Target ferritin >100 µg/L to confirm adequate iron repletion. 1
• If hemoglobin does not respond after 4 weeks despite compliance, perform additional testing including MCV, RDW, and repeat ferritin to evaluate for other causes of anemia. 1

Long-Term Management

• Once the underlying cause is treated and iron stores are restored (ferritin >100 µg/L), continue hemoglobin monitoring. 1
• If chronic bleeding cannot be controlled, expect the need for ongoing iron supplementation, potentially with regularly-scheduled IV iron infusions. 1

Critical Pitfalls to Avoid

• Do not rely on faecal occult blood testing—it has no benefit in investigating iron deficiency anemia. 1
• Do not skip celiac disease screening; it is found in 3-5% of IDA cases and is a treatable cause. 1
• Do not stop investigation after finding one potential source—multiple causes may coexist (e.g., celiac disease plus GI bleeding). 1
• Do not use blood transfusions unless there is cardiovascular instability or hemodynamic compromise—your hemoglobin of 100 g/L does not meet this threshold. 1
• With your severe iron deficiency (ferritin 5 µg/L, transferrin saturation 0.03), failure to identify and treat the underlying cause will result in recurrent anemia despite iron replacement. 1