What is the appropriate management for a patient with elevated Red Cell Distribution Width (RDW) and low Mean Platelet Volume (MPV)?

Management of High RDW and Low MPV

A patient with elevated RDW and low MPV requires immediate investigation for iron deficiency anemia with serum ferritin and transferrin saturation, followed by gastrointestinal evaluation to exclude malignancy if iron deficiency is confirmed. 1, 2

Diagnostic Interpretation

Understanding the Pattern

• High RDW (>14.0%) indicates heterogeneous red cell populations, which strongly suggests iron deficiency anemia, early nutritional deficiencies (B12/folate), or hemolysis 2
• Low MPV suggests bone marrow suppression, cytotoxic drug effects, aplastic anemia, chronic renal failure, or sepsis 3
• This combination is particularly concerning as it may indicate iron deficiency with concurrent marrow dysfunction or systemic illness 2, 3

Critical First Steps

Obtain the following laboratory tests immediately:

• Serum ferritin (<30 μg/L confirms iron deficiency without inflammation; <100 μg/L with inflammation) 1, 2, 4
• Transferrin saturation (<30% supports iron deficiency) 1, 4
• Complete blood count with MCV and reticulocyte count 2, 4
• C-reactive protein (CRP) to assess for inflammation 4
• Comprehensive metabolic panel to evaluate renal and hepatic function 1

Differential Diagnosis Algorithm

If MCV is Low (Microcytic Anemia)

• High RDW + Low MCV strongly indicates iron deficiency anemia 2
• Low MPV in this context suggests concurrent bone marrow suppression or systemic illness 3
• Rule out gastrointestinal blood loss as the primary cause 1

If MCV is Normal (Normocytic Anemia)

• High RDW with normal MCV may indicate early iron deficiency, combined deficiencies (iron plus B12/folate), or hemolysis 2
• The low MPV points toward marrow dysfunction or drug effects 3
• Consider medication review for myelosuppressive agents 3

If MCV is High (Macrocytic Anemia)

• High RDW suggests combined deficiency states 1
• Low MPV indicates marrow suppression is the dominant process 3
• Check B12, folate, and thyroid function 2

Management Based on Confirmed Diagnosis

Iron Deficiency Anemia (Most Likely)

Initiate iron supplementation:

• Oral iron (ferrous sulfate 325 mg three times daily) or intravenous iron if malabsorption suspected 1
• Therapeutic response to three weeks of oral iron confirms diagnosis 1

Mandatory gastrointestinal investigation in adult men and post-menopausal women:

• Upper gastrointestinal endoscopy with small bowel biopsy to exclude celiac disease 1
• Colonoscopy or barium enema to exclude colonic malignancy 1
• Both upper and lower tract examination required even without overt bleeding 1

Concurrent Marrow Suppression

If low MPV persists despite iron repletion:

• Evaluate for sepsis, splenomegaly, or chronic renal failure 3
• Review all medications for myelosuppressive agents 3
• Consider bone marrow aspiration if diagnosis remains unclear 1

Critical Pitfalls to Avoid

• Never assume mild anemia is less concerning than severe anemia—severity does not correlate with likelihood of malignancy 1
• Do not delay gastrointestinal investigation while treating with iron—occult malignancy must be excluded 1
• Do not overlook combined deficiencies—high RDW with normal MCV may mask iron deficiency when folate or B12 deficiency coexists 1, 2
• Low MPV should prompt evaluation for systemic illness or drug toxicity, not just hematologic disorders 3
• Ferritin may be falsely elevated (>12-15 μg/dl) in patients with concurrent inflammation, malignancy, or hepatic disease—use <100 μg/dl as cutoff in these contexts 1

Prognosis and Follow-Up

• High RDW is associated with increased mortality risk in multiple conditions including cardiovascular disease, venous thromboembolism, and systemic illness 5, 6
• Even when no gastrointestinal source is identified, long-term outlook is good with iron supplementation 1
• Monitor complete blood count every 3 months until RDW normalizes and MPV recovers 2
• Persistent low MPV despite treatment warrants hematology referral 3