Prothrombin Time
Haematology marker
PT
Prothrombin Time
Measures the time for blood to clot via the extrinsic and common coagulation pathways. Sensitive to clotting factors I, II, V, VII and X, and used to assess liver synthetic function and vitamin K status.
PED Notes
PT is not a routine PED test, but it is a useful window on liver synthetic function, which matters for users of oral 17-alpha-alkylated AAS. The liver makes most clotting factors, so significant AAS-induced hepatotoxicity can prolong PT. Separately, androgen-driven erythrocytosis raises thrombotic risk through elevated haematocrit rather than through PT, so a normal PT does not exclude clot risk in a polycythaemic athlete. PT (as the INR) is the standard test to monitor warfarin. No PED shifts the healthy target, so the bodybuilder range equals the standard range.
When high
When prolonged (>14 seconds):
- A prolonged PT means the extrinsic pathway is slow to clot. Common causes: warfarin therapy, vitamin K deficiency, liver disease (reduced factor synthesis), or disseminated intravascular coagulation.
- What to do: review warfarin or other anticoagulant use. Check liver function (ALT, AST, GGT, bilirubin, albumin) because a prolonged PT with a low albumin points to failing hepatic synthesis.
- For AAS users on orals with a prolonged PT plus abnormal liver enzymes, prioritise liver recovery (drop or switch off 17-aa orals, hepatoprotection) and recheck.
- Vitamin K supplementation corrects PT only when the cause is deficiency; do not self-treat a prolonged PT without a diagnosis.
When low
When shortened (<11 seconds):
- A slightly short PT is usually not clinically significant on its own, but can accompany a prothrombotic, hypercoagulable state.
- What to do: in an enhanced athlete, focus on the dominant modifiable clot risk, haematocrit. Confirm the sample was not clotted or improperly filled, which can artefactually shorten the time.
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range
VitalMetrics Range