All of the following are true about the activated clotting time (ACT) except:

a. It is useful for monitoring warfarin therapy.
b. It can be performed in the clinic or at the patient's bedside.
c. It uses diatomaceous earth as the clot activator.
d. The clinical laboratory scientist inverts the tube until a clot forms.

ANS: A
The ACT can be used to monitor heparin therapy, not warfarin. Diatomaceous earth is used to activate clot formation, and the clinical laboratory scientist does invert the tube until a clot forms, noting the time needed for this to occur.