What is the treatment for iron deficiency with a ferritin level of 12?

Treatment of Iron Deficiency with Ferritin 12 ng/mL

Oral iron supplementation should be initiated immediately at 100-200 mg elemental iron daily (or on alternate days), as a ferritin of 12 ng/mL indicates depleted iron stores requiring repletion. 1, 2

Diagnostic Confirmation and Context

A ferritin level of 12 ng/mL definitively indicates absolute iron deficiency with depleted or absent iron stores 1. This level falls well below the diagnostic thresholds used across multiple guidelines:

• <15 μg/L confirms iron deficiency in women of childbearing age with 98% specificity 1
• <12 ng/mL indicates no stainable bone marrow iron with 100% specificity 1
• Even the most conservative threshold of <35 μg/L used in athletic populations is exceeded 1

Before initiating treatment, ensure you exclude inflammatory conditions by checking C-reactive protein, as inflammation can falsely elevate ferritin and mask true iron deficiency 2. However, at a ferritin of 12 ng/mL, iron deficiency is present regardless of inflammatory status 1.

First-Line Treatment: Oral Iron Supplementation

Dosing and Administration:

• 100-200 mg elemental iron daily in divided doses is the standard approach 1, 2
• Alternate-day dosing (e.g., ferrous sulfate 325 mg every other day) may improve absorption and reduce gastrointestinal side effects 1, 3
• Administer in the morning on an empty stomach when possible to maximize absorption 4

Specific Formulations:

• Ferrous sulfate 325 mg contains approximately 65 mg elemental iron 3
• Preparations with 28-50 mg elemental iron content may improve compliance by reducing side effects 2

Enhancing Absorption:

• Co-administer with vitamin C to enhance non-heme iron absorption 1
• Avoid tea, coffee, and calcium-containing foods around dosing times as these inhibit absorption 1, 4
• For vegetarians/vegans, emphasize dietary sources with vitamin C co-ingestion 1

When to Consider Intravenous Iron

Intravenous iron should be used as first-line therapy in the following situations 1, 3:

• Active inflammatory bowel disease with compromised absorption 1
• Chronic kidney disease (particularly dialysis-dependent) 1
• Heart failure with ongoing symptoms 3
• Second or third trimester of pregnancy 3, 4
• Celiac disease with malabsorption 1
• Post-bariatric surgery patients 3
• Intolerance to oral iron after adequate trial 1, 2
• Ongoing blood loss that cannot be controlled 1

IV Iron Formulations and Dosing:

• Ferric carboxymaltose allows rapid administration of large single doses (up to 1000 mg) over 15 minutes 1
• Iron sucrose typically dosed at 100-200 mg per session 5
• Test dose of 25 mg is recommended before initiating iron dextran therapy due to anaphylaxis risk 1

Monitoring Treatment Response

Recheck laboratory values after 8-10 weeks of oral iron therapy 1, 2:

• Hemoglobin should increase by 1-2 g/dL 1
• Ferritin should rise significantly (target varies by clinical context)
• Do not recheck ferritin earlier after IV iron as levels will be falsely elevated 1

Treatment Duration:

• Continue oral iron for at least 3 months to replenish stores, targeting ferritin >20-30 ng/mL before discontinuation 2, 4
• In high-risk populations (heavy menstrual bleeding, athletes, vegetarians), consider intermittent maintenance therapy with monitoring every 6-12 months 2

Target Ferritin Levels

The appropriate target ferritin depends on clinical context:

• General population: 30 μg/L for adults >15 years 2
• Athletes: Maintain >35 μg/L to prevent performance decline 1
• Inflammatory bowel disease: Maintain >100 μg/L to prevent anemia recurrence 1
• Chronic kidney disease on dialysis: Maintain >100 ng/mL with transferrin saturation >20% 1
• Pregnancy and menstruating women: Target >30 ng/mL 3

Critical Pitfalls to Avoid

Do not delay treatment waiting for extensive gastrointestinal workup in asymptomatic patients, though evaluation for blood loss sources should occur concurrently 1.

Do not continue iron supplementation indefinitely without monitoring—once ferritin normalizes, reassess need for ongoing therapy as iron overload can be harmful 1, 2.

Do not use ferritin alone in patients with suspected inflammatory conditions; add transferrin saturation (<20% confirms functional iron deficiency) 1.

Gastrointestinal side effects (constipation, nausea, abdominal pain) are common with oral iron and the primary cause of non-adherence 1. Switching to alternate-day dosing or lower elemental iron content preparations can improve tolerance 1, 2.