Hi Liz, According to the FDA Guidance for Industry "Collection of Platelets by Automated Methods" December 2007; a donor should undergo no more than 24 Platelet, pheresis collections in a rolling 12-month period. In addition, the interval between each collection of Platelet via apheresis should be at least two days with no more than two procedures in a seven day period. The interval between the collection of a double or triple platelet donation and any subsequent collection of platelets should be at least 7 days. Hope this helps. Tom