How should I manage a ferritin level of 13 ng/mL?

Management of Ferritin Level 13 ng/mL

You should immediately initiate oral iron supplementation with ferrous sulfate 325 mg daily (or on alternate days for better absorption and tolerability) to treat this absolute iron deficiency, while simultaneously investigating the underlying cause of iron loss. 1, 2

Diagnostic Confirmation

Your ferritin of 13 ng/mL definitively confirms absolute iron deficiency by all current diagnostic criteria:

• Ferritin <30 ng/mL is diagnostic of iron deficiency in individuals without inflammatory conditions 1
• Ferritin <45 ng/mL is diagnostic in adult patients without inflammation 2
• Even more conservative thresholds recognize ferritin ≤50 ng/mL as indicative of early iron deficiency 3, 4

At this level, you have depleted iron stores with or without anemia present. 1

Immediate Treatment Protocol

First-Line Oral Iron Therapy

Start ferrous sulfate 325 mg:

• Alternate-day dosing (every other day) improves absorption compared to daily dosing 2
• If daily dosing is preferred, take 325 mg once daily 1
• Continue for at least 3 months to fully replenish iron stores, not just until hemoglobin normalizes 5, 6
• Target ferritin levels >100 ng/mL and transferrin saturation >20% 5, 6

Expected timeline:

• Evaluate response in 2-4 weeks with repeat hemoglobin 2
• Recheck ferritin and transferrin saturation after 3 months of treatment 6

When to Use Intravenous Iron Instead

Switch to IV iron (ferric carboxymaltose or iron sucrose) if: 1, 2

• Oral iron intolerance (occurs in ~50% of patients) 2
• Malabsorption conditions (celiac disease, post-bariatric surgery, atrophic gastritis) 1
• Ongoing blood loss 1
• Chronic inflammatory conditions (CKD, heart failure, IBD, cancer) 1
• Second or third trimester of pregnancy 1
• Inadequate response to oral iron after 2-4 weeks 2

Critical Diagnostic Workup for Underlying Cause

You must identify why the ferritin dropped to 13 ng/mL. Recurrent blood loss is responsible for 94% of iron deficiency cases. 2

For Premenopausal Women:

• Assess for heavy menstrual bleeding as the most likely cause 1
• If heavy menstrual bleeding is present and patient is young with no alarm symptoms, treat the bleeding and provide iron supplementation 2
• Consider noninvasive testing for H. pylori and celiac disease (both common causes) 2

For Men and Postmenopausal Women:

• Bidirectional endoscopy (upper and lower) is mandatory to evaluate for gastrointestinal bleeding 2
• Test for H. pylori infection and celiac disease 2
• Check stool for occult blood 6

For All Patients:

• Obtain complete blood count to assess for anemia 6
• Measure transferrin saturation simultaneously with ferritin (should be <20% in iron deficiency) 1, 2
• Assess dietary iron intake 1
• Review medications, especially NSAIDs (increase GI bleeding risk) 1
• Screen for inflammatory bowel disease if clinically indicated 1

Common Pitfalls to Avoid

• Do not stop iron supplementation when hemoglobin normalizes—continue for at least 3 months until ferritin reaches >100 ng/mL 5, 6
• Do not use ferritin alone without checking transferrin saturation for complete iron status assessment 7, 5
• Do not delay investigation of the underlying cause, especially in men and postmenopausal women where GI malignancy must be excluded 2
• Do not assume dietary insufficiency alone in men or postmenopausal women—pathologic blood loss is far more likely 2
• Do not supplement with vitamin C during treatment, as it accelerates iron mobilization and increases oxidative stress 6

Monitoring Strategy

• Week 2-4: Check hemoglobin to confirm response 2
• Month 3: Recheck ferritin and transferrin saturation 6
• If ferritin remains low or continues declining despite treatment, consider IV iron and intensify investigation for ongoing blood loss 6
• Monthly ferritin monitoring may be appropriate if clinical concern for ongoing loss is high 6