Thrombocytopenia is a condition in which you have a low blood platelet count. Platelets (thrombocytes) are colorless blood cells that help blood clot. Platelets stop bleeding by clumping and forming plugs in blood vessel injuries.Thrombocytopenia often occurs as a result of a separate disorder, such as leukemia or an immune system problem. Or it can be a side effect of taking certain medications. It affects both children and adults.Thrombocytopenia may be mild and cause few signs or symptoms. In rare cases, the number of platelets may be so low that dangerous internal bleeding occurs. Treatment options are available.Thrombocytopenia signs and symptoms may include:Easy or excessive bruising (purpura)Superficial bleeding into the skin that appears as a rash of pinpoint-sized reddish-purple spots (petechiae), usually on the lower legsProlonged bleeding from cutsBleeding from your gums or noseBlood in urine or stoolsUnusually heavy menstrual flowsFatigueEnlarged spleenJaundice