All labs have a different reference range
, in one of medical books, it says the normal range
is 150,000 to 300,000. Thrombocytopenia (reduced platelet count) is usually caused, but not always, by certain infections, some anemias. They play an important role in blood coagulation and thrombus (clot) formation.
I am not about the menstrual cycle causing this, I have heard that pregnancy can. Also, excessive alcoholic consumption can reduce the number as can the blood thinner, Heparin.