What's the next step for a patient with low ferritin, low iron saturation, and normal Total Iron-Binding Capacity (TIBC)?

Iron Deficiency Management with Low Ferritin (10 ng/mL), Low Saturation, and Normal TIBC

Start oral iron supplementation immediately with 28-50 mg elemental iron daily, as this presentation indicates absolute iron deficiency requiring treatment. 1

Understanding Your Iron Studies

Your laboratory pattern is diagnostic of absolute iron deficiency:

• Ferritin 10 ng/mL is severely depleted (well below the 30 µg/L threshold for healthy adults >15 years), indicating exhausted iron stores 1
• Low transferrin saturation confirms insufficient iron available for red blood cell production 2
• Normal TIBC argues against inflammatory conditions that could confound the diagnosis 2

The lower the ferritin and saturation, the higher the likelihood of true iron deficiency, and at ferritin 10 ng/mL, you are definitively iron deficient. 2

Immediate Treatment Steps

First-Line: Oral Iron Therapy

Begin oral iron supplementation with 28-50 mg elemental iron daily (such as ferrous sulfate 324 mg tablets containing 65 mg elemental iron, taken every other day or daily based on tolerance). 1, 3

• Lower doses (28-50 mg elemental iron) reduce gastrointestinal side effects and improve compliance compared to higher doses 1
• Take with vitamin C-rich foods to enhance absorption; avoid calcium, tea, and coffee within 2 hours 1
• Continue for at least 8-10 weeks before reassessing 1

Concurrent Evaluation

Investigate the underlying cause of iron deficiency:

• For menstruating women: Heavy or prolonged menstrual bleeding is the most common cause 1
• For men and postmenopausal women: Gastrointestinal blood loss must be evaluated with endoscopy, as this population should not develop iron deficiency without pathology 4
• For all patients: Consider dietary insufficiency, malabsorption (celiac disease, autoimmune gastritis, post-bariatric surgery), or chronic blood loss 1

Monitoring Response

Recheck complete blood count and iron parameters (ferritin, TSAT, serum iron, TIBC) at 8-10 weeks:

• Do NOT check iron studies within 4 weeks of starting treatment, as circulating iron interferes with assays 2
• Hemoglobin should increase by 1-2 g/dL within 4-8 weeks 2
• Target ferritin ≥30 µg/L (≥50 ng/mL in absence of inflammation) 1, 2
• Target TSAT ≥20% 2

When to Consider Intravenous Iron

Reserve IV iron for specific situations:

• Intolerance to oral iron (severe gastrointestinal side effects) 1, 4
• Failure to respond to adequate oral therapy after 8-10 weeks 1
• Malabsorption conditions preventing oral iron uptake 1
• Urgent need for rapid correction (though this is rarely the case in otherwise healthy individuals) 5

If IV iron becomes necessary, modern formulations (ferric carboxymaltose, iron derisomaltose, iron sucrose) allow total dose infusion in 1-2 weeks with <1% risk of moderate-to-severe reactions. 5

Long-Term Management

For patients with recurrent iron deficiency:

• Intermittent oral iron supplementation to maintain stores once replete 1
• Monitor ferritin every 6-12 months 1
• Address ongoing blood loss or malabsorption definitively 1

Critical Caveat

Do not supplement iron if ferritin is normal or elevated, as this provides no benefit and may cause harm. 1 Your ferritin of 10 ng/mL clearly indicates deficiency requiring treatment, but future monitoring ensures you stop supplementation once stores are replete.

Common Pitfalls to Avoid

• Don't wait for anemia to develop: Iron deficiency without anemia still causes fatigue, impaired cognitive function, and reduced physical performance 1
• Don't check ferritin during acute illness: Ferritin is an acute phase reactant and can be falsely elevated during inflammation; check C-reactive protein if concerned 1
• Don't use excessive iron doses: Higher doses increase side effects without improving efficacy 1
• Don't ignore the underlying cause: Treating iron deficiency without addressing the source leads to recurrence 4