Management of Ferritin 11 ng/mL in Adults
An adult with ferritin 11 ng/mL has severe iron deficiency with absent iron stores and requires immediate iron replacement therapy with oral ferrous sulfate 100-200 mg elemental iron daily (or every other day for better absorption and tolerability), continued for 3-6 months to replenish stores, along with investigation of the underlying cause. 1
Diagnostic Confirmation
Ferritin 11 ng/mL is highly specific for iron deficiency (specificity 0.99) and indicates absent bone marrow iron stores, falling well below the diagnostic threshold of <15 μg/L. 1
This level is significantly below the lower limit of normal (15-30 μg/L for most laboratories) and confirms absolute iron deficiency regardless of inflammation status. 1
Check hemoglobin, mean cell volume (MCV), and mean cell hemoglobin (MCH) to assess severity and guide monitoring. 1
Measure transferrin saturation (TSAT) as an additional marker; TSAT <20% confirms inadequate iron availability for erythropoiesis. 1, 2
Investigation of Underlying Cause
All adults with confirmed iron deficiency at this level require evaluation for the source of iron loss or malabsorption:
In men and postmenopausal women: Bidirectional endoscopy (upper and lower GI tract) is mandatory, as recurrent blood loss accounts for 94% of cases and GI malignancy risk is significant. 1, 2
In premenopausal women: If heavy menstrual bleeding provides a plausible explanation and there are no GI symptoms or family history of GI pathology, treat the bleeding source and provide iron supplementation without immediate endoscopy. 1
Screen for celiac disease serologically in all patients, as it is found in 3-5% of iron deficiency cases and represents a treatable cause of malabsorption. 1
Perform urinalysis or urine microscopy to exclude urinary blood loss. 1
Test for Helicobacter pylori infection, which is a common cause of iron deficiency. 2
First-Line Treatment: Oral Iron
Oral iron replacement is the recommended first-line therapy for most patients without contraindications:
Dosing: Ferrous sulfate 100-200 mg elemental iron daily. 3, 2
Every-other-day dosing improves absorption and reduces gastrointestinal side effects compared to daily dosing, which may enhance adherence. 2
Use preparations with reasonable elemental iron content (28-50 mg per dose if using every-other-day strategy, or 100-200 mg daily) to balance efficacy and tolerability. 3
Duration: Continue for 3-6 months after hemoglobin normalizes to replenish iron stores, as correction of anemia precedes store repletion. 3, 2
Common pitfall: Approximately 50% of patients have decreased adherence due to gastrointestinal adverse effects (constipation, nausea, abdominal discomfort). 3, 2
Monitoring Response to Oral Iron
Reassess in 2-4 weeks with complete blood count to confirm hemoglobin response (expected rise of 1-2 g/dL within 4-8 weeks). 4, 2
Repeat ferritin and TSAT at 8-10 weeks to assess store repletion. 3
Target goals: Ferritin ≥50 ng/mL and TSAT >20% to ensure adequate iron stores. 5, 2
If no response occurs after 4 weeks of adequate oral therapy, consider intravenous iron or investigate for ongoing blood loss, malabsorption, or non-adherence. 2
Indications for Intravenous Iron
Switch to intravenous iron if:
Intolerance to oral iron with significant gastrointestinal side effects preventing adherence. 2
Inadequate response to oral iron after 4 weeks of appropriate dosing. 2
Malabsorption is present (e.g., celiac disease, inflammatory bowel disease). 3
Rapid correction is medically necessary. 3
Intravenous Iron Formulation and Dosing
Ferric carboxymaltose (Injectafer) is the preferred formulation for rapid, high-dose repletion: 750 mg IV in two doses separated by at least 7 days (total 1,500 mg per course) for patients ≥50 kg, or 15 mg/kg per dose for patients <50 kg. 4
Alternative: Single dose of 15 mg/kg up to maximum 1,000 mg may be administered. 4
Dilute in 100 mL normal saline and infuse over at least 15 minutes. 4
Do not re-measure iron parameters within 4 weeks of IV iron administration, as circulating iron interferes with assay accuracy. 6, 4
Reassess ferritin and TSAT at 4-8 weeks post-infusion; maximal benefit is expected at 12 weeks. 6, 4
Safety monitoring: Check serum phosphate in patients requiring repeat courses within 3 months, as ferric carboxymaltose carries risk of hypophosphatemia. 6, 4
Hypersensitivity reactions are rare (<1% with modern formulations) but monitor during administration. 2
Repeat Treatment and Long-Term Monitoring
Repeat iron studies every 3-6 months in patients with history of iron deficiency to detect recurrence early. 5
If ferritin remains <50 ng/mL or TSAT <20% at follow-up, repeat iron supplementation. 6, 5
Upper safety limits: Withhold iron when TSAT >50% or ferritin >800 ng/mL to prevent iron overload. 1, 6
Long-term daily oral or IV iron supplementation in the presence of normal or high ferritin is not recommended and is potentially harmful. 1, 3
Dietary Counseling
Integrate heme iron (meat, poultry, fish) and non-heme iron (legumes, fortified cereals) regularly into the diet. 1, 3
Enhance absorption by consuming iron with vitamin C-rich foods. 3
Avoid inhibitors of iron uptake (tea, coffee, calcium supplements) at mealtimes. 3
Dietary modification alone is insufficient to correct established deficiency but supports maintenance after repletion. 3
Critical Pitfalls to Avoid
Do not delay investigation of the underlying cause in men or postmenopausal women, as GI malignancy is a significant risk. 1, 2
Do not stop iron therapy when hemoglobin normalizes; continue for 3-6 months to replenish stores. 3
Do not measure iron parameters within 4 weeks of IV iron, as results will be falsely elevated. 6, 4
Do not supplement iron if ferritin is normal or elevated without confirming deficiency, as excess iron is potentially harmful. 1, 3
Ferritin can be falsely elevated as an acute-phase reactant during inflammation; if clinical suspicion for iron deficiency persists despite ferritin >45 μg/L, measure TSAT or soluble transferrin receptor. 1, 2