From the Guidelines
Order Prothrombin Time (PT) when a patient is on Vitamin K Antagonists (VKAs) or has a suspected coagulopathy due to trauma or bleeding, as PT is an excellent assay for monitoring VKAs and can help identify coagulopathy in trauma patients 1.
- PT measures the reduction of vitamin K-dependent clotting factors, including factors II, VII, IX, and X, and is used to monitor patients on VKAs, such as warfarin 1.
- In patients on VKAs, PT is used to calculate the International Normalized Ratio (INR), which standardizes the PT assay and allows for accurate monitoring of anticoagulation therapy 1.
- While PT can be affected by Direct Oral Anticoagulants (DOACs), such as rivaroxaban, it is not a reliable test for monitoring DOACs, and other tests, such as anti-Xa activity, may be more suitable 1.
- In trauma patients, PT can be used as a first-line test to supply a qualitative assessment of coagulation, but it should be interpreted with caution, as it may not accurately reflect the presence or absence of DOACs 1.
- Viscoelastic coagulation tests, such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM), may be useful in detecting coagulopathy associated with DOACs and guiding reversal therapy, but their availability and interpretation may be limited in some settings 1.
From the Research
Ordering Prothrombin Time (PT)
There are no research papers to assist in answering this question, as the provided studies focus on osteoporosis treatment and fracture prevention, with no mention of Prothrombin Time (PT) or its ordering criteria.
- The studies 2, 3, 4, 5, 6 discuss various treatments for osteoporosis, such as teriparatide, denosumab, and bisphosphonates, and their effects on bone mineral density and fracture risk.
- None of the studies provide information on when to order Prothrombin Time (PT), which is a test used to evaluate blood clotting.
- Therefore, there is no relevant evidence to provide guidance on ordering PT based on the provided studies.