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Residual Platelet Distribution Width in Thrombocytosis

Description

When the platelet count shows a moderate increase, it may be difficult to distinguish between reactive (secondary) and autonomous (primary) thrombocytosis. In many cases the platelet count, mean platelet volume and platelet distribution width do not allow distinction between these groups. Analysis of the platelet distribution width can be useful in the differential diagnosis of thrombocytosis.


 

expected platelet distribution width =

= 79.5 - (0.005 * (platelet count)) - (3.5 * (mean platelet volume in femtoliters))

 

where:

• platelet count number used is (number) * 10^9/L

 

residual platelet distribution width =

= (expected platelet distribution width) - (observed platelet distribution width)

 

Interpretation:

• The mean residual platelet distribution width for the reactive thrombocytosis group is close to 0.

• No patients with myeloproliferative disorders had a residual PDW below the 50th percentile value for the reactive thrombocytosis group.

• 76% of patients with myeloproliferative disorders had a residual PDW above the 95th percentile value for the reactive thrombocytosis group.

 


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