What Result Triggers a PTT Mix? QQ Summary

Here is the summary of our October-November, 2015 Quick Question, “What PTT value initiates a PTT mixing study in your laboratory?” The question drew 157 responses.

1. Any PTT result longer than the upper limit of the reference interval: 25%
2. PTT result longer than the upper limit of the reference interval pending physician consult: 18%
3. PTT result at least 5 seconds longer than the upper limit of the reference interval: 36%
4. Another limit: 20%

I’ve never had a Quick Question with such evenly divided answers, clearly there is no consensus on when to start PTT mixing studies. The key is to be consistent within your institution and to perform mixes in consultation with the physician who is managing the patient. We’ve now posted a new Quick Question for you to consider.