Labs to Know

what does Prothrombin Time (PT) measure

how long it takes for blood to clot

what if PT is low?

blood is clotting faster than normal

what if PT is high/

blood is taking longer than normal to clot

What does International normalized Ratio (INR) measure

how long it takes a person’s blood to clot

what if INR is low

blood is clotting too quickly, which increases your risk of developing a blood clot

what if INR is high?

blood is clotting too slowly, which increases the risk of bleeding

Why are PT and INR presented together?

b/c INR is standardized calculations of the PT that allows for consistent and comparable results across different labs and testing methods

with what medications should we monitor PT and INR?

oral anticoagulants like warfarin

what is normal INR

~1

What is therapeutic INR?

varies, usually 2-3

what does Partial thromboplastin Time (PTT)?

measures how long it takes for blood clot

with what medications should we monitor PTT?

unfractionated heparin therapy

what is the normal range for PTT?

21-35 seconds

what is the normal range of therapeutic PTT

varies, usually 60-80 seconds

what does D-Dimer measures?

the presence of D-Dimers, a protein fragment that is a byproduct of blood clots breaking down

what if D-dimers are abnormal?

body may be producing blood clots that are breaking down, but does not confirm a clot’s presence or location