A measure of variation in platelet size.
PDW-SD, platelet distribution width by standard deviation, measures how much platelet size varies in your blood. A wider value means the platelets differ more in size, a narrower value means they are more uniform.
It is one of the platelet indices reported automatically by haematology analysers during a complete blood count. It is read together with the platelet count and mean platelet volume.
Platelet size variation can reflect how actively the bone marrow is producing platelets. A high PDW often goes with newly released, larger platelets, which can occur when platelets are being used up or replaced quickly.
On its own PDW is not diagnostic, but combined with other platelet indices it can support the picture of platelet activation, bone marrow response, or certain inflammatory states.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
Typical adult guidance, strongly analyser dependent:
| Result | Range |
|---|---|
| PDW-SD | 9 to 17 fL |
This index has no single agreed reference range and differs between analyser models. Always read your result against your laboratory's interval.
Platelet clumping, delayed analysis, and EDTA-related platelet changes can distort the result. Values are not comparable between different analyser brands. PDW is rarely used alone to make decisions.
Read alongside platelet count, mean platelet volume, plateletcrit, and the platelet large cell ratio.
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