The most common cause of high platelet pressure is an increase in the number of platelets. There are primary and reactive increases in the number of platelets, and the most common primary increases are in myeloproliferative diseases, such as true erythropoietic disease, primary thrombocytosis, early stages of myelofibrosis, and chronic granulocytic leukemia. Reactive increases are common in acute infections such as acute appendicitis, acute pneumonia, acute cholecystitis, etc. Platelet counts are also increased in patients with acute hemolysis and certain cancers, such as lung cancer and liver cancer. There is another condition where platelet pressure is also high, which is when the body is heavily dehydrated, such as severe diarrhea, vomiting, and heavy sweating, etc. Due to the dehydration of the body, the concentration of platelets increases, which will also cause high platelet pressure. However, after rehydration, the platelet pressure will return to normal.