Platelets are cell fragments made by bone marrow that help the blood clot to prevent bleeding and help wounds to heal. While high platelet count can be due to underlying infection, it may also be a sign of a serious bone marrow disorder such as thrombocythemia or primary thrombocytosis, according to the Mayo Clinic. Platelet disorders characterized by high platelet levels can put you at risk for developing blood clots. While you may not notice any symptoms, bleeding and abnormal sensations caused by blood clots can occur.
Too many platelets in the bloodstream can cause the formation of blood clots in large and small blood vessels anywhere in the body. If a blood clot partially blocks a vessel, it can interfere with the amount of blood and oxygen that reach bodily tissues. Consequently, you may experience tingling, numbness, "pins and needles" or other abnormal sensations in the hands and feet called paresthesias, according to the Merck Manuals Online Medical Library.
You may also notice your hands, fingertips, feet or toes feeling unusually cold to the touch. Impaired blood flow can also affect your blood pressure, causing you to feel dizzy or weak. Blood clots in the small vessels of the eye or large clots in bigger vessels of the body can impair vision, causing blurriness or other visual disturbances. Persistent headaches and chest pain may also be a sign of abnormal clotting due to high platelet count.
Excess platelet count associated with thrombocythemia or primary thrombocytosis may also cause bleeding. According to the Merck Manuals Online Medical Library, this bleeding is usually mild and commonly results in nosebleeds, oozing from the gums or bleeding within the stomach or digestive tract. You may also bruise easily or notice unexplainable skin bruising. Bloody stools, bleeding from the respiratory tract or prolonged bleeding after surgical procedures or tooth extraction can also occur, according to the National Institutes of Health. Some people may also develop ulcers on their fingers or toes.
If blood clots form and completely block the flow of blood through a blood vessel, or if they break off from a blood vessel and travel to the heart, lungs or brain, they can cause life-threatening symptoms of a stroke or heart attack, according to the National Institutes of Health.
Spleen and liver enlargement and severe hemorrhage from bleeding that cannot be stopped can also occur. Some people may develop primary myelofibrosis--a disorder that occurs as a result of scarring of the bone marrow. Primary myelofibrosis causes blood to form on the liver or spleen, resulting in abdominal bloating due to the swelling of internal organs.