What is the treatment for low iron stores (hypoferritinemia)?

Treatment of Low Iron Stores (Hypoferritinemia)

Start oral ferrous sulfate 200 mg (65 mg elemental iron) once daily as first-line treatment, and continue for 3 months after hemoglobin normalizes to fully replenish iron stores. 1, 2

Initial Oral Iron Therapy

• Ferrous sulfate 200 mg once daily is the recommended first-line treatment because it is the most cost-effective and well-established option 1, 2
• Each 200 mg tablet contains 65 mg of elemental iron 3
• If once daily dosing is not tolerated due to gastrointestinal side effects, switch to alternate-day dosing rather than discontinuing treatment 2
• Alternative formulations include ferrous fumarate or ferrous gluconate, which are equally effective 1, 2
• Avoid modified-release preparations as they have reduced absorption and are less suitable 2

Enhancing Absorption and Tolerability

• Add ascorbic acid (vitamin C) 250-500 mg with each iron dose to enhance absorption, particularly if response is poor 1, 2
• Lower doses of 50-100 mg elemental iron daily may be better tolerated while maintaining reasonable efficacy 2
• Consider preparations with 28-50 mg elemental iron content to prevent reduced compliance from gastrointestinal side effects 4

Duration and Monitoring

• Continue oral iron for 3 months after hemoglobin normalizes to adequately replenish marrow iron stores 1, 2
• Check hemoglobin at 2 weeks to confirm response—expect at least a 10 g/L (1 g/dL) rise 2
• Hemoglobin should increase by 2 g/dL after 3-4 weeks of treatment 1, 2
• Repeat testing at 8-10 weeks to assess treatment success 2, 4
• Monitor hemoglobin and red cell indices every 3 months for one year, then annually 1

When Oral Iron Fails

Failure to achieve expected hemoglobin rise indicates:

• Non-compliance (most common) 1, 2
• Continued blood loss 1, 2
• Malabsorption 1, 2
• Misdiagnosis 1

Indications for Intravenous Iron

Switch to IV iron when: 1, 2, 5

• Intolerance to at least two different oral iron preparations
• No hemoglobin rise ≥10 g/L after 2 weeks of daily oral therapy
• Malabsorption conditions (celiac disease, inflammatory bowel disease, post-bariatric surgery)
• Chronic inflammatory conditions (chronic kidney disease, heart failure, inflammatory bowel disease, cancer)
• Ongoing blood loss that cannot be controlled
• Second and third trimesters of pregnancy
• Severe symptomatic anemia requiring rapid correction

Calculating IV Iron Doses

• Calculate total cumulative IV iron doses based on formulas for body iron deficit to correct hemoglobin and rebuild stores 1
• Administer doses every 3-7 days until total dose is given 1
• Do not exceed maximum single dose per formulation 1
• Monitor serum ferritin and keep below 500 µg/L to avoid iron overload toxicity, especially in children and adolescents 1

Blood Transfusion

• Transfusion is rarely indicated for iron deficiency because most patients adapt to slowly developing anemia 2
• Reserve transfusion only for severe symptomatic anemia with circulatory compromise 2
• If transfused, target hemoglobin 70-90 g/L (80-100 g/L with unstable coronary disease), then follow with iron replacement 2

Investigating Underlying Causes

Always identify and treat the source of iron loss: 1, 2

• Age >45 years: Perform upper endoscopy with small bowel biopsy AND colonoscopy to exclude gastrointestinal bleeding or malignancy
• Age <45 years: Screen for celiac disease (anti-endomysial antibodies with IgA level); perform endoscopy only if upper GI symptoms present
• Menstruating women: Heavy menstrual bleeding is common, but still investigate if age >45 years or symptoms persist
• Exclude urinary tract bleeding by checking for hematuria 1

Critical Pitfalls to Avoid

• Don't stop oral iron when hemoglobin normalizes—continue for 3 months to replenish stores 1, 2
• Don't use parenteral iron as first-line unless specific contraindications exist (painful, expensive, risk of anaphylaxis) 1, 2
• Don't assume dietary deficiency alone—always investigate for pathological blood loss in adults 2
• Don't supplement iron if ferritin is normal or high—this is potentially harmful 2, 4
• Don't use long-term daily iron supplementation in the presence of normal or high ferritin values 4

Long-Term Management

• Patients with repeatedly low ferritin benefit from intermittent oral substitution to preserve iron stores 4
• Monitor with basic blood tests every 6-12 months in patients requiring long-term follow-up 4
• Additional oral iron should be given if hemoglobin or MCV falls below normal 1