I had a full blood count test performed before SRS and it was discovered that my platelet count was 85 x 10*9 per liter. The normal range is 150 - 400 x 10*9 per liter.
Following that test, I had a prothrombin time (PT) test, which showed clotting to be normal. In fact, everything else showed normal. I had a specialist review all the results and declared that the low platelet count was no impediment to having SRS. It appears that I have a naturally low platelet count.
My SRS surgeon wasn't in the least concerned about the tests. Anyway, the surgery was completed without any issue.
Apparently, you have to be lower than 18 x 10*9/L before it starts affecting clotting.
I've been on HRT for 20 years and it's never shown to be a problem.