Activated protein-C is a protein (protein) from the blood clotting system. It is dependent on vitamin K.
APC resistance (synonym: factor V Leiden mutation (FVL mutation); note: V stands for the number five) is a mutation in a blood clotting factor, factor V, making it resistant to protein-C. This results in an increased tendency to thrombosis.
In the heterozygous form (= inherited from only one parent) of APC resistance, the risk of thrombosis is increased 5-10-fold. In the homozygous form (= inherited from both parents), the risk is 50-100-fold.
The procedure
Material needed
- EDTA blood (a completely filled tube).
Preparation of the patient
- Not necessary
Disruptive factors
- Not known
Normal value
| Rating | APC Ratio |
| No evidence for a factor V mutation | > 2,3 |
| V.a. heterozygous form | 1,5-2,3 |
| V.a. homozygous form | < 1,5 |
Ratio is determined by measuring PTT with/without addition of protein-C.
Indications
- Suspicion of increased thrombotic tendency (thrombophilia screening).
Interpretation
Interpretation of increased values
- Not relevant to disease
Interpretation of lowered values
- Increased tendency to thrombosis
Other indications
