Platelets
What it measures, and what changes the number.
The platelet count measures how many platelets, the small cell fragments involved in blood clotting, are present in a given volume of blood. It is one of the core results of a complete blood count and is produced by an automated analyzer.
It is usually read with mean platelet volume, platelet distribution width and plateletcrit, which describe platelet size, and with the white and red cell counts from the same sample. Clotting tests such as prothrombin time may be ordered alongside it.
The blood goes into an anticoagulant tube. In some people platelets clump together in that tube, which makes the machine count fewer than are really there; labs often check a smear or repeat the count in a different tube when this is suspected. A difficult draw can also start clotting in the tube. Reports may show it as Plaquetas, Plaquetes or PLT.
Often read alongside: MPV, PDW, Plateletcrit, White blood cells, Red blood cells