Question on blood draws. A few years ago, I worked in a clinic setting, and would draw blood a few times a week. Mostly CBCs and chemistry. For the chem we would use a "tiger topped" red and gray serum separator tube (SST). For the CBC, the lavender. My question is on the chemistry tube. I know that in hospitals, plasma separator tubes are used (not the SSTs), which are the "mint" green-topped tubes, for speed, but also, I'm now reading, because heparinized plasma is preferred over serum for potassium. Who knew?? Why don't clinics likewise use the mint topped PSTs? Is it a question of economy because a whole range of tests can come from that one SST? Am I missing something?Thoughts?Thanks!