Plateletcrit (PCT)
Haematology marker
Plateletcrit
Plateletcrit (PCT)
The fraction of blood volume occupied by platelets, analogous to the haematocrit for red cells. It is calculated from the platelet count and mean platelet volume and reflects total platelet mass. It is reported as one of the platelet indices on a full blood count.
PED Notes
A minor platelet index that summarises total platelet mass, best interpreted with the platelet count and MPV. Note the common source-PDF mislabel: some labs print plateletcrit under a 'PCT' abbreviation, and it can be confused with platelet distribution width, but the percentage unit identifies it as plateletcrit. Not directly affected by AAS; occasionally relevant to the broader thrombotic-risk picture in enhanced athletes with erythrocytosis or hypertension, but rarely actionable in isolation.
When high
When high (>0.35%):
- Reflects a high total platelet mass, usually mirroring a raised platelet count; interpret with the platelet count and MPV
- Reactive thrombocytosis (infection, inflammation, iron deficiency, post-exercise) is the common driver; a persistently raised platelet count with high plateletcrit warrants the same workup as thrombocytosis (see the Platelets marker)
- In an enhanced athlete with concurrent erythrocytosis or hypertension, manage overall thrombotic risk (hydration, blood pressure, haematocrit control, and consider low-dose aspirin only under medical supervision) rather than the plateletcrit number itself
When low
When low (<0.15%):
- Reflects a low total platelet mass, usually mirroring a low platelet count (thrombocytopenia); confirm with the platelet count and follow the low-platelet guidance under the Platelets marker
- On its own, a modestly low plateletcrit with a normal platelet count is not clinically significant
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range