The shortest living factor
Factor VII initiates the extrinsic coagulation pathway when a vessel is damaged and has the shortest half-life of all factors, only 4–6 hours. Because of this, it is the first to decrease when synthesis in the liver is impaired and when there is a deficiency of vitamin K, and this is why prothrombin time lengthens earlier than other indicators in liver disease and when starting to take warfarin. Determination of factor VII is prescribed to clarify the cause of an isolated prolongation of prothrombin time with a normal aPTT, if a hereditary deficiency of factor VII is suspected - a rare but clinically significant disease with bleeding, as well as to assess the synthetic function of the liver in severe hepatitis and cirrhosis, where the indicator serves as one of the early markers of liver failure.
How to prepare to donate blood
- on an empty stomach 8–12 hours, you can drink water
- Eliminate alcohol and intense exercise per day
- no smoking in an hour
- donate blood before physiotherapy, x-rays and massage
- Take medications in advance by agreeing with your doctor
How to read the result
Reference values depend on the method and equipment of the laboratory, so it is correct to compare results only within the same laboratory. A deviation of a few percent from the normal limit in itself rarely matters - the overall picture and dynamics are important.
The analysis must be interpreted by a doctor: an isolated indicator without a clinical context is often misleading and leads to unnecessary examinations.