What is the recommended management for an asymptomatic 42‑year‑old woman with mild anemia, normocytic mean corpuscular volume, low ferritin (iron deficiency), normal reticulocyte count, adequate folate, low‑normal vitamin B12, and no heavy menstrual bleeding?

Management of Asymptomatic Iron Deficiency Anemia in a 42-Year-Old Woman

Start oral ferrous sulfate 200 mg once daily immediately, add vitamin C 500 mg with each dose, and investigate the underlying cause with bidirectional endoscopy (upper endoscopy and colonoscopy) to exclude gastrointestinal malignancy. 1

Immediate Treatment Protocol

Begin oral iron supplementation now without waiting for further diagnostic workup. 1 Your patient has confirmed iron deficiency anemia based on:

• Ferritin 26 ng/mL (< 30 ng/mL confirms absolute iron deficiency) 1
• Iron saturation 16% (< 20% indicates iron depletion) 1
• Hemoglobin 10.4 g/dL (< 12 g/dL defines anemia in women) 1

Specific Oral Iron Regimen

• Prescribe ferrous sulfate 200 mg (65 mg elemental iron) once daily – this is the most cost-effective first-line therapy 1, 2
• Add vitamin C 500 mg with each iron dose to enhance absorption, especially critical given the low iron saturation of 16% 1, 2
• Take on an empty stomach for optimal absorption; if gastrointestinal side effects occur, taking with food is acceptable 1, 2
• Avoid tea and coffee within 1 hour of the iron dose, as these inhibit absorption 2

Do not prescribe multiple daily doses – once-daily dosing is superior because hepcidin remains elevated for ~48 hours after each dose, blocking further absorption and increasing side effects without improving efficacy 1, 2

If ferrous sulfate is not tolerated, ferrous fumarate or ferrous gluconate are equally effective alternatives 1, 2

Expected Response and Monitoring

• Check hemoglobin at 4 weeks – expect a rise of approximately 2 g/dL (from 10.4 to ~12.4 g/dL) 1, 2
• Continue oral iron for 3 months after hemoglobin normalizes to fully replenish iron stores; total treatment duration will be 6–7 months 1, 2
• Monitor hemoglobin and red-cell indices every 3 months during the first year, then again after another year 1, 2

Mandatory Investigation of Underlying Cause

All women over 40 years with iron deficiency anemia require gastrointestinal investigation to exclude malignancy, even without symptoms. 1

Diagnostic Algorithm

Step 1: Assess menstrual blood loss first 1, 2

• Although you state "no heavy menstrual bleeding," verify this with pictorial blood loss assessment if needed 2
• Menorrhagia accounts for iron deficiency in 5–10% of menstruating women 1, 2

Step 2: Screen for celiac disease 1, 2

• Order tissue transglutaminase IgA antibodies and total IgA 1, 2
• Celiac disease is present in 3–5% of iron deficiency cases and can cause treatment failure if missed 2

Step 3: Test for Helicobacter pylori 2

• Use stool antigen or urea breath test 2
• Eradication improves iron absorption in positive cases 2

Step 4: Bidirectional endoscopy 1

• Upper endoscopy with small-bowel biopsies to exclude gastric cancer, peptic ulcer disease, and celiac disease 1
• Colonoscopy to exclude colorectal cancer and polyps 1
• This is mandatory in your patient because she is over 40 years old, even though she is asymptomatic 1

Important timing consideration: If colonoscopy is scheduled within the next few days, delay starting oral iron because it can impair endoscopic visualization 1, 2

Additional Laboratory Considerations

Your patient's vitamin B12 of 219 pg/mL is low-normal and may contribute to suboptimal response. Consider B12 supplementation if hemoglobin fails to rise adequately after 4 weeks. 1, 2

The folate level of 3.6 ng/mL is adequate and does not require supplementation. 1

When to Switch to Intravenous Iron

Switch to IV iron if any of the following occur: 1, 2

• Intolerance to at least two different oral iron preparations (ferrous sulfate, fumarate, or gluconate) 1, 2
• Ferritin fails to improve after 4 weeks of compliant oral therapy 1, 2
• Hemoglobin fails to rise by ≥1 g/dL after 4 weeks 2
• Celiac disease with inadequate response despite strict gluten-free diet adherence 1, 2

If IV iron becomes necessary, prefer formulations that replace the deficit in 1–2 infusions (ferric carboxymaltose 750–1000 mg or ferric derisomaltose 1000 mg) rather than multiple infusions 1, 2

Critical Pitfalls to Avoid

• Do not stop iron therapy when hemoglobin normalizes – continue for an additional 3 months to replenish stores 1, 2
• Do not persist with oral iron beyond 4 weeks without a hemoglobin rise – reassess for malabsorption, ongoing loss, or need for IV iron 1, 2
• Do not overlook vitamin C supplementation when oral iron response is suboptimal 1, 2
• Do not fail to investigate the underlying cause – gastrointestinal malignancy may present solely with iron deficiency 1
• Do not assume "no heavy menstrual bleeding" excludes menorrhagia – objective assessment may be needed 2
• Do not miss celiac disease screening – its 3–5% prevalence in iron deficiency can cause treatment failure 2

Failure to Respond Algorithm

If anemia does not resolve within 6 months despite appropriate iron therapy: 1, 2

1. Verify patient adherence to oral iron therapy 2
2. Evaluate for ongoing blood loss (repeat endoscopy or video capsule endoscopy) 2
3. Consider malabsorption syndromes (celiac disease, inflammatory bowel disease) 2
4. Check for concurrent vitamin B12 or folate deficiency 2
5. Consider hematology consultation for complex cases 2