My grandpa has a high blood platelet reading, around 500-600 * 10^9/l. his doctor in china tried methods to lower the blood platelet but doesn't work well. i'm looking for advice or recommended medicine for my grandpa to control his platelet. thanks.

Hematologist: Thrombocytosis can be dangerous and a hematologist is best qualified to treat and follow this proliferative disorder of platelets. Certain medications are available for this but should be prescribed by a specialist with experience with them.

No quick fix: High platelets count is either disease on its own, primary, or a sign of another disorder, secondary. In either case if it is persistent, the patient needs to be seen by a Hematologist, trying to just lower the number won't work, it should be treated as a whole systemic problem, good luck