How should I diagnose and treat a reproductive‑age woman with low mean corpuscular volume, low mean corpuscular hemoglobin, low mean corpuscular hemoglobin concentration, hemoglobin around 11 g/dL, and menorrhagia?

Diagnosis and Management of Iron‑Deficiency Anemia with Menorrhagia

Immediate Treatment Protocol

Start oral ferrous sulfate 200 mg (≈65 mg elemental iron) once daily immediately, together with vitamin C 500 mg, without waiting for further diagnostic work‑up. 1

Your laboratory findings confirm severe iron deficiency: MCV, MCH, and MCHC are all decreased (microcytic, hypochromic anemia), hemoglobin is 11.0 g/dL (below the 12.0 g/dL threshold for women), and the clinical context of menorrhagia makes this diagnosis straightforward. 2

Oral Iron Regimen

• Ferrous sulfate 200 mg once daily is the preferred first‑line therapy because it provides superior cost‑effectiveness with efficacy comparable to other oral iron salts. 1
• Take the dose on an empty stomach for maximal absorption; if gastrointestinal side effects occur, it may be taken with food. 1
• Co‑administer vitamin C 500 mg with each iron dose to markedly enhance absorption, especially critical when iron stores are severely depleted. 1, 2
• Once‑daily dosing is superior to multiple daily doses because hepcidin remains elevated for ~48 hours after each dose, blocking additional absorption and increasing side effects without improving efficacy. 1
• If ferrous sulfate is not tolerated, ferrous fumarate or ferrous gluconate are equally effective alternatives. 1

Expected Response and Monitoring

• Check hemoglobin at 4 weeks; an increase of approximately 2 g/dL is expected (from 11.0 g/dL to ≈13.0 g/dL). 1, 3
• 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 the second year. 1

Investigation of Underlying Cause

Menstrual Blood Loss Assessment

In reproductive‑age women, assess menstrual blood loss first because menorrhagia, pregnancy, and breastfeeding account for iron deficiency in 5–10% of menstruating women. 1, 4, 5

• Use pictorial blood‑loss assessment charts to objectively quantify menstrual bleeding; these tools demonstrate ≈80% sensitivity and specificity for detecting menorrhagia. 1
• Heavy menstrual bleeding is the most common cause of iron deficiency in reproductive‑age women and requires specific gynecologic evaluation and management. 4, 5, 6

Celiac Disease Screening

Screen for celiac disease with tissue transglutaminase IgA antibodies and total IgA measurement because celiac disease is present in 3–5% of iron‑deficiency cases and can cause treatment failure if missed. 1, 2

When Gastrointestinal Investigation Is Needed

In women under 45 years without upper‑GI symptoms, gastrointestinal endoscopy is NOT indicated. 1

Reserve bidirectional endoscopy (upper endoscopy + colonoscopy) for women who:

• Are ≥50 years old 1
• Have gastrointestinal symptoms (abdominal pain, altered bowel habits, overt bleeding) 1
• Have alarm features or a strong family history of colorectal cancer 1
• Fail to respond to adequate oral iron after 8–10 weeks 1

When to Switch to Intravenous Iron

Switch to IV iron when any of the following criteria are met:

• Intolerance to at least two different oral iron formulations (e.g., ferrous sulfate and ferrous fumarate or gluconate) 1
• Ferritin fails to improve after 4 weeks of compliant oral therapy 1
• Hemoglobin fails to rise by ≥1 g/dL after 4 weeks 1
• Active inflammatory bowel disease with hemoglobin <10 g/dL 1
• Post‑bariatric surgery patients (disrupted duodenal absorption) 1
• Celiac disease with inadequate response despite strict gluten‑free diet adherence 1

Preferred IV Iron Formulations

• 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 as a single infusion 1
• Avoid iron dextran as first‑line due to higher anaphylaxis risk (≈0.6–0.7%) 1
• All IV iron must be administered in a setting equipped with resuscitation facilities 1

Management of Heavy Menstrual Bleeding

While iron replacement corrects the anemia, definitive treatment of menorrhagia is essential to prevent recurrence. 4, 5, 6

Gynecologic evaluation should assess for:

• Uterine fibroids (leiomyomas) – a leading cause of menorrhagia 7
• Hormonal disorders
• Structural uterine abnormalities
• Coagulation disorders

Treatment options for menorrhagia include hormonal therapies, tranexamic acid, or surgical interventions depending on the underlying cause. 6

Critical Pitfalls to Avoid

• Do not prescribe multiple daily doses of oral iron; this increases side effects without improving efficacy due to hepcidin‑mediated absorption blockade. 1
• Do not stop 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 fail to address the underlying menorrhagia while supplementing iron; recurrence is inevitable without treating the source of blood loss. 4, 5
• Do not miss celiac disease screening; its 3–5% prevalence in iron‑deficiency cases can lead to treatment failure. 1

Failure‑to‑Respond Algorithm

If anemia persists after 4 weeks of adequate oral iron:

1. Verify adherence to oral iron therapy 1
2. Re‑evaluate menstrual blood loss and consider gynecologic interventions for persistent menorrhagia 1
3. Re‑screen for malabsorption, especially celiac disease 1
4. Check for concurrent vitamin B12 or folate deficiency 1
5. Consider switching to IV iron if oral therapy failure is confirmed 1
6. If anemia remains unresolved after 6 months, proceed with gastrointestinal investigation 1