Diagnosis: Iron Deficiency Anemia
This 18-year-old female has iron deficiency anemia (IDA), confirmed by the combination of low hemoglobin, microcytosis (low MCV), hypochromia (low MCH and MCHC), and elevated RDW—a pattern that strongly indicates iron deficiency. 1, 2, 3
Diagnostic Confirmation
The laboratory pattern presented is characteristic of IDA:
- Low MCV, MCH, and MCHC indicate microcytic hypochromic anemia, the hallmark of iron deficiency 1, 3
- Elevated RDW combined with low MCV strongly suggests iron deficiency anemia rather than thalassemia trait (which typically has normal RDW) 1, 2
- Serum ferritin is the single most useful confirmatory test: A level <30 μg/L in the absence of inflammation confirms iron deficiency 1, 2
- If ferritin is equivocal (30-100 μg/L), check transferrin saturation; <20% supports iron deficiency 1
Critical Pitfall to Avoid
Do not assume thalassemia trait based solely on ethnicity and microcytosis without checking ferritin levels—this is a common diagnostic error 1, 3
Investigation for Underlying Cause
All patients with confirmed IDA require gastrointestinal evaluation to identify the source of blood loss, even in young menstruating women. 1
Essential History Elements
- Menstrual history: Quantify blood loss (number of pads/tampons per day, duration, clots) 1
- Dietary assessment: Evaluate iron intake, though inadequate diet alone should not preclude GI investigation 1
- Medication use: Document NSAIDs, aspirin, anticoagulants 1
- GI symptoms: Abdominal pain, change in bowel habits, dysphagia, though symptoms poorly correlate with findings 1
Gastrointestinal Investigation Algorithm
- Upper endoscopy with small bowel biopsies to screen for celiac disease (present in 2-3% of IDA patients) 1
- Colonoscopy should follow unless upper endoscopy reveals cancer or celiac disease, as dual pathology occurs in ~10% of cases 1
- Consider these investigations even in young women, as the threshold for investigation should be low with any degree of anemia in the presence of confirmed iron deficiency 1
Treatment
Initiate oral iron supplementation immediately upon confirming iron deficiency. 1, 2
Oral Iron Therapy
- Ferrous sulfate 324 mg (65 mg elemental iron) daily is the standard first-line treatment 4
- A hemoglobin rise ≥10 g/L within 2 weeks confirms iron deficiency, even if iron studies were equivocal 1
- Continue treatment for 3-6 months after hemoglobin normalizes to replenish iron stores 1
Important Counseling Points
- Take iron 2 hours apart from tetracycline antibiotics to avoid absorption interference 4
- Common side effects include gastrointestinal discomfort, nausea, constipation, or diarrhea 4
- If oral iron fails due to intolerance or malabsorption, intravenous iron is the alternative 5
Monitoring Response
- Recheck complete blood count in 2 weeks to confirm hemoglobin rise 1
- Failure to respond suggests ongoing blood loss, malabsorption, or incorrect diagnosis 1, 5
Management of Lightheadedness
The lightheadedness is directly attributable to anemia and should resolve with iron repletion and hemoglobin normalization 1. No additional specific intervention for lightheadedness is needed beyond treating the underlying IDA.