Platelets – Part 3 – Platelet Indices
Platelet Indices
This is the automated calculation of the platelets indices which consists of:
- Mean platelet volume (MPV).
- Plateletcrit (Pct).
- Platelet distribution width (PDW).
Indications
- Platelet indices are potentially useful markers for the early diagnosis of thromboembolic diseases.
- MPV and PDW help in discriminating causes of thrombocytopenia as hypoproductive or hyper-destructive like immune thrombocytopenic purpura.
- An increase in both mean platelet volume (MPV) and platelet distribution width (PDW) due to platelet activation, was suggested due to :
- Platelet swelling.
- Pseudopodia formation.
- MPV and PDW are simple platelet indices, which increase during platelet activation.
Mean Platelet Volume (MPV)
- Definition: MPV is a machine-calculated measurement of the average size of platelets found in blood and is typically included in blood tests as part of the CBC.
- Primarily with thrombocytopenia when it is due to:
- Impaired production as in aplastic anemia.
- MPV is higher when there is the destruction of platelets.
- This may be seen as inflammatory bowel disease.
- In immune thrombocytopenic purpura (ITP).
- In myeloproliferative diseases and Bernard-Soulier syndrome.
- It may also be related to preeclampsia and recovery from transient hypoplasia.
- Low MPV values will be associated with bleeding.
- In the case of the release of immature platelets to the circulation, which is larger in size leads to raised MPV.
- In the case of ineffective platelet formation in the bone marrow, as their size is smaller then there is low MPV.
- MPV is very useful in the case of thrombocytopenia.
- Primarily with thrombocytopenia when it is due to:
Plateletcrit (Pct)
- Plateletcrit is an effective screening tool for detecting platelet quantitative abnormalities.
- Normal platelet count has a Plateletcrit within the range of 0.20 to 0.36%.
- Normal Values
- The average of Mean platelet volume was 9.13 fl.
- Plateletcrit- 0.23%.
- Platelet distribution width – 56.6% of normal platelet counts.
- Sensitivity and specificity for detection of :
- Thrombocytopenia at the Plateletcrit cutoff range of 0.20 – 0.36% is 97 and 80%.
- Thrombocytosis is 94 and 98%.
Platelet distribution width (PDW)
- PDW is a simple, practical, and specific marker of activation of coagulation.
- PDW is a more specific marker of platelet activation since it does not increase during simple platelet swelling.
- PDW has been receiving attention due to its usefulness for distinguishing between reactive thrombocytosis and thrombocytosis associated with the myeloproliferative disorder.
- The determination of the PDW reference range is fundamental.
- Mean platelet volume (MPV) and platelet distribution width (PDW) are useful in the differential diagnosis of aplastic anemia and idiopathic thrombocytopenic purpura.
- An increased PDW is an indication of the anisocytosis of platelets.
- Standard PDW ranges from 9 to 14 fL.