What treatment is recommended for a low iron level?

Treatment for Low Iron Levels

Start ferrous sulfate 200 mg once daily in the morning on an empty stomach as first-line treatment for iron deficiency. 1

First-Line Oral Iron Therapy

Ferrous sulfate 200 mg once daily is the preferred regimen due to superior tolerability and effectiveness compared to multiple daily dosing, while remaining the most cost-effective option. 2, 1 This represents a shift from older recommendations of divided doses throughout the day. 2

Dosing Strategy

• Take as a single morning dose rather than divided throughout the day 1
• Administer on an empty stomach for optimal absorption, though taking with food is acceptable if gastrointestinal side effects occur 1
• Add vitamin C (ascorbic acid) 500 mg with each iron dose to enhance absorption, particularly when response is suboptimal 2, 1
• Alternate-day dosing may be considered for doses ≥60 mg to maximize fractional iron absorption and reduce side effects 3

Expected Response and Treatment Duration

• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment 2, 1
• Continue oral iron for 3 months after anemia correction to fully replenish iron stores 2, 1
• If no hemoglobin rise occurs within 4 weeks, assess for non-adherence, ongoing blood loss, malabsorption, or misdiagnosis 2, 1

When to Use Intravenous Iron Instead

Switch to IV iron as first-line therapy in the following situations:

• Clinically active inflammatory bowel disease 1
• Hemoglobin <10 g/dL 1
• Previous oral iron intolerance (failed at least two oral preparations) 2, 1
• Malabsorption syndromes including celiac disease or post-bariatric surgery 1
• Chronic inflammatory conditions such as chronic kidney disease, heart failure, or cancer 4
• Second and third trimesters of pregnancy when rapid correction is needed 4
• Ongoing blood loss exceeding intestinal absorption capacity 5

Monitoring Schedule

• Check hemoglobin and red cell indices at 3-month intervals for the first year 2, 1
• Recheck after another year 2, 1
• Provide additional iron supplementation if hemoglobin or MCV falls below normal 2, 1

Special Population Considerations

Pregnant Women

• Start 30 mg/day at first prenatal visit for primary prevention 2
• Increase to 60-120 mg/day for treatment of anemia 2, 1
• Decrease to 30 mg/day when hemoglobin normalizes for gestational stage 2, 1
• Refer to specialist if hemoglobin <9.0 g/dL or hematocrit <27.0% 2, 1

Inflammatory Bowel Disease

• Treat active inflammation first to enhance iron absorption and reduce iron depletion 1
• Use IV iron as first-line in clinically active disease 1

Post-Bariatric Surgery

• Prefer IV iron due to disrupted duodenal absorption mechanisms 1

Critical Pitfalls to Avoid

• Do not prescribe multiple daily doses – once-daily or alternate-day dosing improves tolerability with similar or better efficacy 1, 3
• Do not stop iron when hemoglobin normalizes – continue for 3 months to replenish stores 2, 1
• Do not continue oral iron indefinitely without response – reassess after 4 weeks and switch to IV iron if hemoglobin fails to rise 2, 1
• Do not overlook vitamin C supplementation when oral iron response is suboptimal 2, 1
• Do not use parenteral iron routinely – reserve for specific indications as it is painful, expensive, and carries anaphylaxis risk 2

Investigation of Underlying Cause

While treating with iron supplementation, identify and address the underlying cause of iron deficiency:

• Patients >45 years: Investigate with bidirectional endoscopy (upper GI endoscopy with small bowel biopsy and colonoscopy) due to increasing incidence of significant pathology with age 2, 1
• Patients <45 years: Perform endoscopy only if upper GI symptoms present; otherwise test antiendomysial antibodies to exclude celiac disease 2, 1
• Menstruating women: Consider menorrhagia as primary cause, though those >45 years should still undergo GI investigation 2

Treatment Failure Management

If anemia does not resolve within 6 months despite appropriate iron therapy:

• Reassess for ongoing blood loss, malabsorption syndromes, non-adherence, or misdiagnosis 2, 1
• Consider further gastrointestinal investigation with small bowel evaluation 1
• Consider hematology consultation for complex cases 1
• Further evaluate with MCV, RDW, and serum ferritin if no response after 4 weeks 2
• Consider thalassemia minor or sickle cell trait in women of African, Mediterranean, or Southeast Asian ancestry with mild anemia unresponsive to iron therapy 2