Treatment of Microcytic Anemia in a 39-Year-Old Female
Start oral ferrous sulfate 324 mg (65 mg elemental iron) one to three times daily immediately, continue for at least three months after hemoglobin normalizes to replenish iron stores, and simultaneously investigate the underlying source of iron loss. 1, 2
Immediate Treatment Protocol
Initiate ferrous sulfate 324 mg tablets one to three times daily as first-line therapy. 2, 3 This provides 65 mg of elemental iron per tablet and should not be crushed or chewed. 3
Add ascorbic acid (vitamin C) 200-500 mg with each iron dose to enhance absorption. 1, 2 This significantly improves iron uptake from the gastrointestinal tract.
If gastrointestinal side effects occur, switch to alternative formulations such as ferrous gluconate or ferrous fumarate. 1, 2 These are equally effective but may be better tolerated.
Continue treatment for at least three months after hemoglobin normalizes to fully replenish iron stores, not just correct the anemia. 1, 2 This is a critical step that is often overlooked in clinical practice.
Expected Response and Monitoring Schedule
Hemoglobin should rise ≥1 g/dL within 2 weeks of starting treatment, confirming iron deficiency as the cause. 2 A rise of ≥10 g/L (≥1 g/dL) within this timeframe is considered a good response. 1
Expect hemoglobin increase of at least 2 g/dL within 4 weeks. 1, 2 Failure to achieve this response warrants further investigation.
Monitor hemoglobin, hematocrit, MCV, and MCH at 2 weeks, 4 weeks, 3 months, then every 3 months for the first year, then annually. 2 This ensures adequate response and prevents recurrence.
Mandatory Investigation of Underlying Cause
This is a critical step that must not be skipped. Iron deficiency anemia in a 39-year-old woman requires explanation, as the body does not spontaneously lose iron without a source. 1, 4
Investigate for heavy menstrual bleeding first, as this is the most common cause in premenopausal women. 1 Detailed menstrual history including duration, frequency, and clot passage is essential.
Evaluate for gastrointestinal blood loss through history of melena, hematochezia, or occult bleeding. 1 Even without overt symptoms, GI sources must be considered.
Screen for celiac disease if malabsorption is suspected, particularly if there are gastrointestinal symptoms or treatment failure. 1 This is a frequently missed cause of iron deficiency.
Assess dietary intake, though dietary deficiency alone is uncommon in developed countries unless there are strict dietary restrictions. 1, 5
Consider H. pylori infection or autoimmune atrophic gastritis if treatment failure occurs, as these can impair iron absorption. 1
When to Consider Intravenous Iron
Switch to intravenous iron (iron sucrose or iron gluconate) if: 1, 2
Documented malabsorption is present (e.g., celiac disease, inflammatory bowel disease). 1, 2
Patient cannot tolerate oral iron despite trying alternative formulations. 2
No hemoglobin response after 4 weeks of adequate oral therapy. 2 This suggests either non-compliance, ongoing blood loss exceeding replacement capacity, or malabsorption.
Ongoing blood loss exceeds oral replacement capacity. 2
Differential Diagnosis Considerations
While iron deficiency is most likely given the low MCV (73.7 fL) and clinical context, other causes must be excluded if treatment fails: 1, 6
Thalassemia trait should be considered if MCV is disproportionately low relative to degree of anemia (MCV <70 fL with mild anemia) or if iron studies are normal. 1, 5 Hemoglobin electrophoresis would show elevated hemoglobin A2 in beta-thalassemia trait. 5
Anemia of chronic disease typically presents with low iron, low total iron-binding capacity, and ferritin >100 μg/L. 1 This is less likely in an otherwise healthy 39-year-old woman.
Rare genetic disorders (IRIDA, sideroblastic anemia) should be considered only if there is failure to respond to both oral and intravenous iron, family history of refractory anemia, or extreme microcytosis (MCV <70). 1
Critical Pitfalls to Avoid
Do not assume all microcytic anemia is iron deficiency without confirming with serum ferritin. 1 Ferritin <45 μg/L provides optimal sensitivity and specificity for iron deficiency. 1, 2
Do not stop iron therapy once hemoglobin normalizes. 1, 2 Continue for at least three months to replenish iron stores, or anemia will recur.
Do not fail to investigate the source of iron loss. 1, 2 In a 39-year-old woman, this is mandatory to prevent recurrence and exclude serious pathology.
Do not overlook combined deficiencies. 1 Iron deficiency can coexist with B12 or folate deficiency, which may blunt the response to iron therapy alone.