What is the diagnosis and treatment for a patient with low hemoglobin, high Red Cell Distribution Width (RDW), low Mean Corpuscular Hemoglobin (MCH), and low Mean Corpuscular Volume (MCV)?

Diagnosis: Iron Deficiency Anemia

This presentation of low hemoglobin, high RDW, low MCH, and low MCV is iron deficiency anemia until proven otherwise, and you should immediately confirm with serum ferritin and initiate oral iron supplementation while investigating the underlying cause. 1

Diagnostic Confirmation

The combination of microcytic (low MCV) and hypochromic (low MCH) red cells with elevated RDW is the classic laboratory signature of iron deficiency anemia. 1

Key distinguishing feature: The elevated RDW combined with low MCV strongly favors iron deficiency over thalassemia trait, which typically presents with low MCV but normal RDW. 1

Confirmatory Testing Required

• Serum ferritin is the single most useful test: A level <30 μg/L in the absence of inflammation confirms iron deficiency. 1
• If ferritin is equivocal (30-100 μg/L): Check transferrin saturation; <20% supports iron deficiency. 1
• Additional iron studies to order: Serum iron, total iron-binding capacity (TIBC will be elevated in iron deficiency), and transferrin saturation. 2, 3

Critical pitfall: Ferritin is an acute phase reactant and can be falsely elevated by inflammation, infection, or chronic disease. When inflammation is present, ferritin up to 100 μg/L may still be consistent with iron deficiency. 3

Investigation for Underlying Cause

All patients with confirmed iron deficiency anemia require gastrointestinal evaluation to identify the source of blood loss, even in young menstruating women. 1

Specific History to Obtain

• Menstrual history in women: Quantify blood loss by number of pads/tampons per day, duration of menses, presence of clots. 1
• Medication review: Document NSAIDs, aspirin, anticoagulants (all increase GI bleeding risk). 1
• Dietary assessment: Evaluate iron intake, though inadequate diet alone should not preclude GI investigation. 1
• GI symptoms: Abdominal pain, change in bowel habits, dysphagia—though note that symptoms correlate poorly with findings. 1

GI Investigation Algorithm

1. Upper endoscopy with small bowel biopsies to screen for celiac disease (present in 2-3% of IDA patients). 1
2. Colonoscopy should follow unless upper endoscopy reveals cancer or celiac disease. 1
3. Low threshold for investigation: Consider these investigations even in young women with any degree of anemia in the presence of confirmed iron deficiency. 1

Treatment Protocol

Initiate oral iron supplementation immediately upon confirming iron deficiency—do not wait for complete workup. 1

Oral Iron Regimen

• Standard dose: 65 mg elemental iron daily. 2
• Recheck complete blood count in 2 weeks: A hemoglobin rise ≥10 g/L confirms iron deficiency, even if iron studies were equivocal. 1, 2
• Duration: Continue treatment for 3-6 months after hemoglobin normalizes to replenish iron stores. 1

Non-Response Management

Failure to respond suggests ongoing blood loss, malabsorption, or incorrect diagnosis. 1

For non-responders or those who cannot tolerate oral iron:

• Consider intravenous iron therapy. 2
• Reassess diagnosis and investigate for concurrent conditions. 2

Important consideration: Even mild anemia should be investigated as it may indicate serious underlying pathology such as GI malignancy. 2