Where are platelets stored?

The spleen is an organ where platelets are stored. About 25% to 30% of red blood cells (RBCs) are stored in the spleen, along with about 25% of platelets normally sequestered in the spleen. The spleen is an organ that is part of the lymphatic system. 

The spleen controls the level of white blood cells, red blood cells, and platelets (small cells that form blood clots). It screens the blood and removes any old or damaged red blood cells.