What are Platelets?

When a blood vessel is damaged, platelets reach it first: they clump together at the site and release factors that trigger the formation of a clot. Too few of them and a small injury goes on bleeding; too many and clots form where they are not needed.

Platelets, RBC Count and WBC Count all trace back to the same stem cells in the bone marrow. When one of the three changes and the other two hold steady, the change belongs to that cell line alone; when all three move, it belongs to the marrow's output as a whole.

The number in circulation is the difference between what megakaryocytes release and what clotting consumes. Infection, inflammation and iron deficiency all raise release; bleeding consumes platelets faster than usual as vessels are sealed.

Megakaryocytes can change how many platelets they release within days, and a bleed subtracts from the count on top of that. Both effects fade within weeks of their cause. A year between tests is long enough that neither is still in the count, so what shows is the level the marrow settles at. This is Do Health's monitoring schedule, not a general recommendation for everyone.