Here is a note I posted 11/16/07 under the heading, “Why All the PTTs?”
It seems that many North American institutions are moving more and more to the use of low molecular weight heparin (mostly Lovenox in the US) and pentasaccharide (Fondaparinux, Arixtra) in place of standard unfractionated heparin. Yet, the lab volume of partial thromboplastin time (PTT, APTT) tests seems to be holding steady. What are all those PTTs for if we are no longer monitoring heparin? And, shouldn’t the volume of anti-Xa heparin assays be increasing?
Our current quick question survey bears this out, as the proportions match the volumes of the PT volume quick question we posted in August. Here is the PTT question with the PT results posted behind the current answers:
What is your partial thromboplastin (APTT, PTT) volume?
a. None: 1 (6%); PT 35%
b. 0-500/day: 12 (71%); PT 54%
c. 500-1000/day: 2 (12%); PT 7%
d. >1000/day 2 (12%); PT 4%
It looks like we are still linking PT and PTT orders, and it may be that many of these PTTs are superfluous. Geo
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