Mean Platelet Volume (MPV): Definition, Normal Range, and Clinical Significance
What is MPV?
Mean Platelet Volume (MPV) is an automated measurement on a Complete Blood Count (CBC) that reflects the average size of platelets in femtoliters (fL), serving as a marker of platelet production and turnover. 1
- The normal reference range for MPV is 7.2-11.7 fL when measured in EDTA anticoagulant at 120 minutes after venipuncture 2
- Alternative reference ranges include 7.2-10.8 fL (EDTA) or 6.1-9.5 fL (citrate anticoagulant) 3
- MPV has an inverse, nonlinear relationship with platelet count throughout the normal range—as platelet count decreases, MPV typically increases 4, 5
Important Technical Considerations
- Timing matters critically: Platelets swell in anticoagulant tubes, reaching stability at 120 minutes in EDTA and 60 minutes in citrate 3
- Citrate samples yield significantly smaller MPV values (7.0 fL) compared to EDTA (8.0 fL) 3
- Erythrocyte or leukemic blast fragments can spuriously affect both MPV and platelet count measurements 4
Causes of Elevated MPV
High MPV with Low Platelet Count
All patients with this pattern have hyperdestructive causes of thrombocytopenia, reflecting increased platelet turnover and younger, larger platelets entering circulation 1:
- Immune thrombocytopenic purpura (ITP)
- Drug-induced thrombocytopenia
- Disseminated intravascular coagulation
- Thrombotic thrombocytopenic purpura
High MPV with Normal Platelet Count
This pattern suggests 1:
- Heterozygous thalassemia (most common—seen in 80% of cases in one study)
- Iron deficiency anemia
- Chronic inflammatory states
High MPV with High Platelet Count
Causes include 1:
- Myeloproliferative disorders (chronic myelogenous leukemia, essential thrombocythemia, polycythemia vera) 6, 1
- Chronic inflammation or infection
- Iron deficiency
- Post-splenectomy state
Causes of Low MPV
Low MPV is strongly correlated with bone marrow suppression and cytotoxic effects 1:
Low MPV with Any Platelet Count (High, Normal, or Low)
All patients with inappropriately low MPV for their platelet count have 1, 5:
- Cytotoxic chemotherapy (most common cause)
- Aplastic anemia
- Sepsis with bone marrow suppression
- Chronic renal failure
- Splenomegaly with splenic sequestration
- Megaloblastic anemia 5
When platelet count is normal but MPV is low, investigate for bone marrow suppression, cytotoxic drug effects, chronic disease states, or splenic sequestration 7
Clinical Management Implications
Bleeding Risk Assessment
- A normal platelet count provides adequate hemostasis regardless of low MPV—prophylactic platelet transfusion is not indicated 7
- Platelet count alone is insufficient for assessing bleeding risk; platelet size and function must be considered together 8
- No specific intervention is needed for abnormal MPV when platelet count remains normal, as bleeding risk is not elevated 7
Diagnostic Workup Based on MPV Pattern
When MPV is high with thrombocytopenia: Evaluate for peripheral destruction (ITP, DIC, TTP) rather than production failure 1
When MPV is inappropriately low: Consider 7, 1:
- Review medication list for cytotoxic agents
- Assess for sepsis or systemic infection
- Evaluate for chronic liver or renal disease
- Consider bone marrow examination if cause unclear
Common Pitfalls to Avoid
- Do not interpret MPV without considering the platelet count—the inverse relationship means "normal" MPV values depend on the concurrent platelet count 4, 5
- Avoid measuring MPV immediately after blood draw; wait 120 minutes for EDTA samples to stabilize 3
- Do not assume low MPV with normal platelet count requires treatment—focus on identifying and treating the underlying cause 7
- Be aware that non-platelet particles (RBC fragments, blast fragments) can spuriously alter both MPV and platelet count 4