What PTT value initiates a PTT mixing study in your laboratory?

Any PTT result longer than the upper limit of the reference interval.
25% (39 votes)
PTT result longer than the upper limit of the reference interval pending physician consult.
18% (29 votes)
PTT result at least 5 seconds longer than the upper limit of the reference interval.
36% (57 votes)
Another limit: please post or email george@fritsmafactor.com.
20% (32 votes)
Total votes: 157