Low prothrombin time (prolonged Quick time) without known anticoagulant treatment

Laboratory tests (citrate tube)

• State on the prescription: “low PT off anticoagulant, to be investigated” (the laboratory scientist may then measure fibrinogen and factors on their own initiative) and any current treatment, in particular direct oral anticoagulant or antibiotic.
• PT and aPTT (repeat)
• Fibrinogen
• Factors II, V, VII and X (if PT remains low)
• ASTif needednon-French guidelineProlonged prothrombin time is frequent in cirrhosis ^[1]; liver function tests clarify the context. Authors’ opinion: no recommendation found on the work-up of an isolated low PT.
• ALTif needednon-French guidelineProlonged prothrombin time is frequent in cirrhosis ^[1]; liver function tests clarify the context. Authors’ opinion: no recommendation found on the work-up of an isolated low PT.
• Bilirubinif needednon-French guidelineProlonged prothrombin time is frequent in cirrhosis ^[1]; liver function tests clarify the context. Authors’ opinion: no recommendation found on the work-up of an isolated low PT.
• Serum albuminif needednon-French guidelineProlonged prothrombin time is frequent in cirrhosis ^[1]; liver function tests clarify the context. Authors’ opinion: no recommendation found on the work-up of an isolated low PT.
• FBC with platelets (if aPTT is also prolonged, or in case of bruising or bleeding)if needednon-French guidelinePT and aPTT both prolonged, bruising or bleeding: the American Family Physician review (2008) then raises disseminated intravascular coagulation, and the German recommendation (DGHO, 2025) places the full blood count in the baseline work-up of a bleeding tendency ^[2,3]. No French recommendation on this point.

• No additional tests as a matter of course to “correct” the PT: discuss with the operator or the hepatologist.