What is the treatment for low ferritin (iron deficiency) in a young female?

Treatment of Low Ferritin in Young Females

Start oral iron supplementation immediately with 60-120 mg elemental iron on alternate days, taken in the morning with vitamin C, for 8-12 weeks to replenish iron stores, even if hemoglobin is normal. 1

Diagnostic Confirmation and Thresholds

• Ferritin <15 μg/L has 99% specificity for absolute iron deficiency and definitively confirms the diagnosis 2, 1
• Ferritin <35 μg/L indicates depleted iron stores and warrants treatment regardless of hemoglobin level 1
• Iron deficiency without anemia still causes significant symptoms including fatigue, lethargy, reduced exercise tolerance, restless legs syndrome, and difficulty concentrating 1, 3

Critical caveat: Before interpreting ferritin, rule out inflammation by checking CRP/ESR, as ferritin is an acute-phase reactant that rises with infection or inflammation and can mask true iron deficiency 1, 4. If inflammatory markers are elevated, use transferrin saturation <16% as an additional marker of iron deficiency 1.

Mandatory Screening

• All young women with low ferritin must be screened for celiac disease with tissue transglutaminase antibodies (tTG Ab) 1
• Evaluate for menorrhagia (the most common cause in premenopausal women), gastrointestinal blood loss, dietary inadequacy, and malabsorption 2, 3

First-Line Treatment: Oral Iron Supplementation

Optimal dosing regimen:

• 60-120 mg elemental iron on alternate days (not daily), taken in the morning (not afternoon/evening) 1, 5
• Co-administer with 250-500 mg vitamin C to enhance absorption 1
• Continue for 8-12 weeks to replenish iron stores 1

Rationale for alternate-day dosing: Oral iron doses ≥60 mg stimulate an acute increase in hepcidin that persists 24 hours and blocks iron absorption from subsequent doses; alternate-day dosing maximizes fractional iron absorption and reduces gastrointestinal side effects 5.

Specific formulations:

• Ferrous sulfate 325 mg (65 mg elemental iron) is the standard, cheapest option 2, 6
• Ferrous gluconate 324 mg (38 mg elemental iron) is equally effective 2, 7
• Slow-release ferrous sulfate formulations are recommended as most tolerable 1
• Liquid preparations may be better tolerated when tablets cause side effects 2

After correcting anemia (if present), continue iron supplementation for 3 months to replenish body stores 2.

Dietary Optimization

• Increase dietary iron intake to at least 18-22 mg/day, focusing on heme iron sources (red meat, seafood) 1
• For vegetarians/vegans, consume non-heme iron with vitamin C to enhance absorption 1

When Oral Iron Fails or Is Inappropriate

Consider intravenous iron for:

• Severe iron deficiency with ferritin <12 μg/L and hemoglobin <11.5 g/dL 1
• Documented malabsorption (celiac disease, inflammatory bowel disease, post-bariatric surgery) 1, 3
• Intolerance to at least two oral iron preparations 2
• Failure to respond to adequate oral supplementation after 3-4 weeks (hemoglobin should rise by 2 g/dL) 2

IV iron formulations: Iron sucrose, ferric carboxymaltose, and ferric derisomaltose are safe and effective options 2, 1.

Monitoring and Follow-Up

• Recheck complete blood count and ferritin at 3 months after starting supplementation to confirm response 2, 1
• Target ferritin level should be at least 35-50 μg/L to ensure adequate stores 1, 4
• For menstruating females at high risk, screen twice yearly for iron deficiency 1
• If hemoglobin fails to rise by 2 g/dL after 3-4 weeks, consider poor compliance, misdiagnosis, continued blood loss, or malabsorption 2

Do not check iron parameters within 4 weeks of starting IV iron, as circulating iron interferes with assays and produces spurious results 2.

Age-Specific Investigation Requirements

• Women <45 years with low ferritin should have upper GI endoscopy with small bowel biopsy only if they have upper GI symptoms 2
• All patients <45 years should have antiendomysial antibody testing (with IgA measurement to exclude IgA deficiency) to exclude celiac disease 2
• Colonic investigation in patients <45 years should only be done if there are specific indications 2
• Women >45 years require both upper GI endoscopy with small bowel biopsy and colonoscopy or barium enema to exclude malignancy 2

Common Pitfalls to Avoid

• Do not give iron doses in the afternoon or evening after a morning dose, as the circadian increase in hepcidin is augmented by morning iron and blocks subsequent absorption 5
• Do not use daily dosing with high-dose iron (>60 mg), as this stimulates hepcidin and reduces absorption while increasing side effects 5
• Do not rely on faecal occult blood testing, as it is insensitive and non-specific 2
• Do not use parenteral iron as first-line therapy unless there is documented intolerance or malabsorption, as it is painful, expensive, and carries risk of anaphylaxis 2