Treatment of Iron Deficiency with Ferritin of 19 ng/mL
Start oral iron supplementation immediately with ferrous sulfate 200 mg three times daily (or 324 mg once daily to every other day), as a ferritin of 19 ng/mL represents clear iron deficiency requiring treatment to restore iron stores and prevent progression to anemia. 1
Diagnostic Confirmation
A ferritin of 19 ng/mL definitively indicates iron deficiency in the absence of inflammation:
- Without inflammation: Ferritin <30 μg/L confirms iron deficiency 1
- With inflammation: Even ferritin up to 100 μg/L may indicate deficiency, but at 19 ng/mL, iron deficiency is present regardless 1
- Check C-reactive protein (CRP) to exclude false interpretation if inflammation is suspected 1, 2
First-Line Treatment: Oral Iron
Initiate oral iron therapy as the standard first-line approach for patients without contraindications:
Dosing Options
- Ferrous sulfate 200 mg three times daily (most cost-effective) 1
- Alternative: Ferrous sulfate 324 mg (65 mg elemental iron) once daily or every other day for better tolerance with comparable absorption 1, 3
- Other ferrous salts (gluconate, fumarate) are equally effective 1
Optimization Strategies
- Take on empty stomach when possible for maximum absorption 1
- Add vitamin C 500 mg with iron to enhance absorption, especially if response is poor 1
- If gastrointestinal side effects occur, switch to alternate-day dosing (better absorption, fewer side effects) 1
- Taking with meals improves tolerance but reduces absorption 1
Duration
- Continue for 3 months after hemoglobin normalization to replenish iron stores 1
- At ferritin 19 ng/mL, expect treatment duration of 3-6 months minimum 1
When to Use Intravenous Iron Instead
Switch to IV iron as first-line therapy in these specific situations:
- Intolerance to at least two oral iron preparations 1
- Active inflammatory bowel disease with compromised absorption 1
- Hemoglobin <100 g/L (if anemic) 1
- Ongoing blood loss not controlled 1
- Malabsorption conditions (celiac disease, post-bariatric surgery) 1, 4
- Second or third trimester pregnancy 4
- Need for rapid repletion (e.g., preoperative optimization) 1
IV Iron Formulation
- Ferric carboxymaltose 1 gram as single dose over 15 minutes is the best-studied option 1
- Allows rapid single-dose administration with low risk (<1:250,000) of serious reactions 1
Monitoring Response
Recheck labs at 8-10 weeks (not earlier, as ferritin remains falsely elevated after IV iron): 1, 2
- Hemoglobin should rise 2 g/dL after 3-4 weeks of oral therapy 1
- Target: Ferritin >30 ng/mL (some experts recommend >50 ng/mL as physiologic threshold) 1, 5
- If no response, consider: non-compliance, continued blood loss, malabsorption, or misdiagnosis 1
Long-Term Management
After successful treatment:
- Monitor every 3 months for first year, then annually 1
- Restart iron supplementation if ferritin drops below 30 ng/mL or hemoglobin/MCV decline 1
- For recurrent deficiency, consider intermittent oral maintenance therapy 2
- In IBD patients specifically, restart IV iron when ferritin drops <100 μg/L 1
Critical Pitfall to Avoid
Never supplement iron when ferritin is normal or elevated (>100-200 ng/mL depending on context), as this is potentially harmful and provides no benefit 1, 2. However, at ferritin 19 ng/mL, treatment is clearly indicated and safe.
Investigate Underlying Cause
While initiating iron therapy, simultaneously evaluate for:
- Menstrual blood loss in premenopausal women (most common cause) 1, 4
- Gastrointestinal bleeding (especially in men and postmenopausal women) 1, 4
- Dietary insufficiency (vegetarian/vegan diet, eating disorders) 2, 4
- Malabsorption (celiac disease, atrophic gastritis, H. pylori) 1, 4
- NSAID use 1, 4
The ferritin level of 19 ng/mL requires treatment regardless of whether anemia is present, as iron deficiency at this level can cause fatigue, cognitive impairment, restless legs syndrome, and reduced physical performance even without anemia 1, 2, 4.