Low platelets - what could be the cause?

Dear Ask The Doctor: Sorry, didn't see a topic on blood. My platelet count is low and has been dropping, discovered on last physical. Two follow up test confirmed the drops. Everything else on the blood test was great. Have an appointment with a mehatologist in 10-days. Looking for a possible cause. Thanks very much.

Dear David: Cause for reduced platelet count may include any of the following such as heavy alcohol consumption, arthritis, viral infections, chemotherapr, certain medications like heparin, quinidine, quinine, sulfa-containing antibiotics, anticonvulsants etc. Detailed history and further evaluation may help identify the cause.