Elevated platelets, also called thrombocytosis is a relatively common finding. If your platelet level is just outside the normal range, then it is probably a meaningless finding that can be followed by future blood counts. However, if your platelet levels are much higher than just above the normal range (ie > 600,000), then you should probably have this evaluated.
Elevated platelets that are much above the normal range (as above) can be due to a blood disorder called essential thrombocytosis. This is where the cells that make platelets grow out of control. Having platelets are too high from this disorder can cause blood clots or even problems with blood clotting. Elevated platelets can be due to a generalized inflammatory state that occurs when the body is fighting off an infection or recovering from a surgery
. Inflammatory disorders such as inflammatory bowel disease or rheumatoid arthritis can cause this. Since you have been feeling tired lately, I would guess that inflammation is a possible cause for your platelets being elevated.
If your platelets are greatly elevated, then you need additional testing done. You could schedule an appointment with a hematologist
. He or she would know what additional testing would need to be done and would be able to perform a bone marrow biopsy if necessary. If your platelets are only mildly elevated, then I would stick to following your blood counts and symptoms with your primary care physician