Prothrombin time (PT)
A prothrombin time (PT) test measures how many seconds it takes for a clot to form in a blood sample. Since the results of this test can vary with different labs or test methods, your results may be used to create an INR (international normalized ratio). Using this ratio makes it easier for health care providers to compare and better understand results from different labs or test methods.
Source: MedlinePlus, U.S. National Library of MedicineNormal range
2 published ranges, each from a named source 1113 seconds drawn: all ages · American Board of Internal Medicine (Laboratory Test Reference Ranges)
- Normal
- 11–15.5 seconds (varies by lab)ABIM 11–13 · ARUP 12–15.5 seconds
These labs do not agree: the published adult ranges differ by up to 19%, so the same result can read as normal at one lab and be flagged at another — ABIM 11–13 · ARUP 12–15.5 seconds. Both are real published values, shown as each lab states them.
Ranges from ARUP Laboratories Test Directory, American Board of Internal Medicine (Laboratory Test Reference Ranges).All source ranges (2)
| Source | Sex | Age | Range |
|---|---|---|---|
| American Board of Internal Medicine (Laboratory Test Reference Ranges) | All | all ages | 11–13 seconds |
| ARUP Laboratories Test Directory | All | all ages | 12–15.5 seconds |
What an abnormal result can be associated with
- A high result
- Prolonged prothrombin time
- A low result
- Decreased prothrombin time
details
- Sample
- Serum or plasma · LOINC
- Part of
- PT panel
- Listed under
- Bleeding Disorders · Blood Clots · Hemophilia
- Code
- LOINC 5902-2 · seconds
- Also known as
- Coagulation assay, Clot, Clottable, Fact, Fac
See your own Prothrombin time (PT) Add a lab report and it is drawn against your lab's range, over time. Upload a Blood Test