Platelets:- Part 3 – Platelet Indices
This is the automated calculation of the platelets indices, which consists of the following:
- Mean platelet volume (MPV).
- Plateletcrit (Pct).
- Platelet distribution width (PDW).
Indications for Platelet Indices
- Platelet indices are potentially useful markers for the early diagnosis of thromboembolic diseases.
- MPV and PDW help discriminate 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 that increase during platelet activation.
Mean Platelet Volume (MPV)
Definition of MPV:
- MPV represents the average size of the platelets.
- It is determined from the arithmetic mean of the platelets histogram provided by the hematology analyzer.
- 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 an 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.
- 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, there is low MPV.
- MPV is very useful in the case of thrombocytopenia.
- It ranges from 7.4 to 10.4 fL
Definition of plateletcrit (Pct):
- Plateletcrit measures the total mass as a percentage of the volume occupied in the blood.
- Plateletcrit is an effective screening tool for detecting quantitative platelet abnormalities.
- Normal platelet count has a Plateletcrit within the 0.20 to 0.36% range.
Normal plateletcrit (Pct)
- Plateletcrit- 0.22 to 0.23%.
- 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)
Definition of Platelet distribution width (PDW)
- It is the measure of variability in the size of platelets.
- 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 received attention due to its usefulness in distinguishing between reactive thrombocytosis and thrombocytosis associated with a 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.
Normal Platelet distribution width (PDW)
- Standard PDW ranges from 9 to 14 fL.
Questions and answers: