How should I evaluate and treat iron‑deficiency anemia in an Asian woman with low hematocrit, low hemoglobin, and low iron studies?

Evaluation and Treatment of Iron‑Deficiency Anemia in an Asian Woman

Immediate First‑Line Oral Iron Therapy

Start oral ferrous sulfate 200 mg (≈65 mg elemental iron) once daily immediately, without waiting for further diagnostic work‑up, unless colonoscopy is scheduled within the next few days. 1

• Take the dose on an empty stomach for maximal absorption; if gastrointestinal side effects occur, it may be taken with food. 1
• Add vitamin C 500 mg with each iron dose to markedly enhance absorption, especially critical when transferrin saturation is severely low. 1, 2
• Once‑daily dosing is superior to multiple daily doses because hepcidin remains elevated for ~48 hours after iron ingestion, blocking further absorption and increasing side effects without improving efficacy. 1
• If ferrous sulfate is not tolerated, ferrous fumarate (≈106 mg elemental iron) or ferrous gluconate (≈38 mg elemental iron) are equally effective alternatives. 1

Expected Hemoglobin Response and Monitoring

• Check hemoglobin at 4 weeks; expect a rise of approximately 2 g/dL. 1
• Continue oral iron for 3 months after hemoglobin normalizes to fully replenish iron stores; total treatment duration is typically 6–7 months. 1
• Monitor hemoglobin and red‑cell indices every 3 months during the first year, then again after another year. 1

Mandatory Investigation of Underlying Cause

In Asian women, the most common causes of iron‑deficiency anemia are heavy menstrual bleeding and gastrointestinal blood loss; both must be systematically evaluated. 1

Menstrual Assessment

• Use pictorial blood‑loss assessment charts to quantify menstrual bleeding; these tools demonstrate ≈80% sensitivity and specificity for detecting menorrhagia. 1
• Menorrhagia, pregnancy, and breastfeeding account for iron deficiency in 5–10% of menstruating women. 1

Malabsorption Screening

• Screen for celiac disease with tissue transglutaminase IgA antibodies and total IgA measurement (to rule out IgA deficiency that could render the test falsely negative). 1
• Celiac disease is present in 2–3% of iron‑deficiency anemia cases and may present with isolated anemia. 1, 2
• Test for Helicobacter pylori infection using stool antigen or urea‑breath test; eradication when positive is recommended in patients with recurrent iron‑deficiency anemia. 1

Gastrointestinal Endoscopy Indications

• Women ≥45 years with iron‑deficiency anemia require bidirectional endoscopy (upper endoscopy with duodenal biopsies + colonoscopy) to exclude gastrointestinal malignancy. 1
• Women <45 years should undergo endoscopy only if they have upper‑GI symptoms (dyspepsia, reflux, epigastric pain), alarm features (rectal bleeding, weight loss), family history of colorectal cancer, or failure to respond to oral iron after 8–10 weeks. 1
• Upper endoscopy with duodenal biopsies screens for celiac disease, gastric cancer, peptic ulcer disease, and NSAID‑induced gastropathy. 1
• Colonoscopy detects colonic carcinoma, adenomatous polyps, angiodysplasia, and inflammatory bowel disease. 1

When to Switch to Intravenous Iron

Switch to IV iron when oral therapy fails or is contraindicated; do not persist with ineffective oral iron beyond 4 weeks without a hemoglobin rise. 1

Absolute Indications

• Intolerance to at least two different oral iron formulations (ferrous sulfate, fumarate, or gluconate). 1
• Ferritin does not improve after 4 weeks of compliant oral therapy. 1
• Active inflammatory bowel disease with hemoglobin <10 g/dL (hepcidin‑mediated absorption blockade). 1
• Post‑bariatric surgery patients (duodenal absorption disrupted). 1

Relative Indications

• Celiac disease with inadequate response despite strict gluten‑free diet adherence. 1
• Ongoing gastrointestinal blood loss that exceeds the replacement capacity of oral iron. 1

Preferred Intravenous Iron Formulations

Choose IV iron products that can replenish the iron deficit in 1–2 infusions to minimize infusion‑related risk and improve convenience. 1

• Ferric carboxymaltose: 750–1000 mg per 15‑minute infusion; two doses given ≥7 days apart provide a total of 1500 mg. 1, 3
• Ferric derisomaltose: 1000 mg can be delivered as a single infusion. 1
• Avoid iron dextran as first‑line due to higher anaphylaxis risk (≈0.6–0.7%). 1
• All IV iron administrations must occur in a setting equipped for emergency resuscitation. 1
• Most infusion reactions are complement‑activation pseudo‑allergies that respond to slowing the infusion rate. 1

Special Considerations for Asian Populations

Thalassemia Screening

• In Asian women, thalassemia trait is a common cause of microcytosis and must be differentiated from iron deficiency. 2
• Order hemoglobin electrophoresis when microcytosis persists despite normal iron studies (ferritin >30 µg/L and transferrin saturation >20%), or when MCV is disproportionately low relative to the severity of anemia. 1, 2
• A low MCV with RDW >14% strongly suggests iron‑deficiency anemia, whereas RDW ≤14% favors thalassemia minor. 2

Dietary Assessment

• Assess for inadequate dietary iron intake, particularly in vegetarian or vegan diets, which increase the risk of iron deficiency in Asian populations. 2

Critical Pitfalls to Avoid

• Do not prescribe multiple daily oral iron doses; this increases side effects without improving efficacy due to hepcidin‑mediated absorption blockade. 1
• Do not discontinue iron therapy when hemoglobin normalizes; continue for an additional 3 months to restore iron stores. 1
• Do not persist with oral iron beyond 4 weeks without a hemoglobin rise; reassess for malabsorption, ongoing loss, or need for IV iron. 1
• Do not overlook vitamin C supplementation when oral iron response is suboptimal. 1
• Do not miss celiac disease screening; its prevalence of 3–5% in iron‑deficiency cases can lead to treatment failure if undetected. 1
• Do not delay endoscopic evaluation in high‑risk patients (age ≥45, alarm symptoms, or treatment failure), as gastrointestinal malignancy may present solely with iron deficiency. 1
• Do not assume all microcytic anemia is iron deficiency; thalassemia trait is particularly common in Asian populations and requires hemoglobin electrophoresis for diagnosis. 2

Failure‑to‑Respond Algorithm

If hemoglobin does not rise by ≥1 g/dL after 4 weeks: 1

1. Verify adherence to oral iron therapy
2. Evaluate for ongoing blood loss (repeat endoscopy or video‑capsule endoscopy)
3. Consider malabsorption syndromes (celiac disease, inflammatory bowel disease, post‑bariatric surgery)
4. Check for concurrent vitamin B12 or folate deficiency
5. Assess for thalassemia trait with hemoglobin electrophoresis
6. Switch to intravenous iron if oral therapy failure is confirmed