Should a female patient of childbearing age with iron deficiency anemia, characterized by a ferritin level of 159, iron saturation of 12%, and an iron level of 31, start iron supplementation?

Should This Patient Start Iron Supplementation?

Yes, this patient should start iron supplementation immediately. Despite the ferritin level of 159 ng/mL appearing "normal," the combination of low hemoglobin (10.7 g/dL), severely low iron saturation (12%), and low serum iron (31) confirms functional iron deficiency with anemia in a woman of childbearing age.

Diagnostic Interpretation

This patient meets criteria for iron deficiency anemia:

• Hemoglobin of 10.7 g/dL is below the threshold of <12 g/dL for non-pregnant women, confirming anemia 1
• Iron saturation of 12% is well below the 20% threshold, indicating insufficient iron available for red blood cell production 1, 2
• The ferritin level of 159 ng/mL does not exclude iron deficiency in this context—ferritin is an acute phase reactant that can be falsely elevated by inflammation, infection, or chronic disease 1

Critical diagnostic principle: When iron saturation is <20% with anemia present, iron deficiency exists regardless of ferritin level, particularly in women of childbearing age 1. The low transferrin saturation indicates functional iron deficiency—meaning insufficient iron is available for erythropoiesis even if storage iron (ferritin) appears adequate 1, 2.

Treatment Recommendation

Start oral iron supplementation as first-line therapy:

• Ferrous sulfate 325 mg once daily (containing approximately 65 mg elemental iron) 3, 4, 2
• Alternative: 100-200 mg elemental iron per day in divided doses 3
• Consider every-other-day dosing to improve absorption and reduce gastrointestinal side effects 2
• Add vitamin C (ascorbic acid) to enhance iron absorption 3

Monitoring and Duration

Follow-up assessment is essential:

• Recheck hemoglobin in 2-4 weeks to confirm response—expect a 1-2 g/dL increase if treatment is effective 2, 5
• Repeat hemoglobin and ferritin after 8-10 weeks of treatment 3
• Continue treatment for at least 3 months after ferritin normalizes to fully replenish iron stores 3
• Target ferritin >100 μg/L to prevent recurrence 3

Investigation of Underlying Cause

For a woman of childbearing age, the approach differs from other populations:

• Heavy menstrual bleeding is the most likely cause and should be evaluated 4, 2
• Gastroenterology evaluation is NOT immediately required for premenopausal women with a plausible explanation (menstrual losses) 1
• Consider non-invasive testing for H. pylori and celiac disease if initial iron supplementation fails 1, 2
• Bidirectional endoscopy is reserved for men and postmenopausal women, or if treatment fails 1, 6

Common Pitfalls to Avoid

Do not be falsely reassured by the ferritin of 159 ng/mL:

• In the presence of low iron saturation (<20%) and anemia, functional iron deficiency exists regardless of ferritin level 1
• Ferritin can be elevated by inflammation, making it an unreliable sole marker in this context 1

Do not delay treatment while investigating the cause:

• Start iron supplementation immediately 3, 4
• Investigation can proceed concurrently with treatment 1

Do not continue supplementation indefinitely:

• Stop once ferritin normalizes and stores are replenished to avoid iron overload 3
• Excessive iron supplementation is potentially harmful 3

If oral iron fails (no hemoglobin increase in 2-4 weeks):

• Consider malabsorption, continued blood loss, or non-adherence 2, 5
• Switch to intravenous iron if oral therapy is not tolerated or ineffective 4, 2