Protein-S (protein S) is a protein (protein) from the blood clotting system that is produced in the liver. It is the cofactor of protein-C, which inhibits blood clotting factors V and VIII.Protein-S is vitamin K-dependent.
Protein-S deficiency results in an increased risk of thrombosis.
The procedure
Material needed
- Citrate plasma
Preparation of the patient
- Not necessary
Disruptive factors
- Completely fill the monovette, there should be no coagulation
- The analysis should be done within a few hours (otherwise freeze).
Normal value – protein S activity
| Normal value in % | |
| 1st day of life (mature/immature) | 14-48 |
| 5th day of life (mature/immature) | 13-64 |
| 1st month of life (mature/immature) | 22-90 |
| 3rd month of life (mature/immature) | 40-112 |
| 6th month of life | 44-120 |
| > 1. year of life/adults | 60-140 |
Normal value – protein S concentration
| Standard value in mg/l | |
| Adults | 17-35 |
- Determination is only useful in the case of decreased activity
Indications
- Suspicion of increased thrombotic tendency (thrombophilia screening).
Interpretation
Interpretation of increased values
- Inflammation, unspecified (acute phase protein).
Interpretation of decreased values
- Elevated factor VIII levels (falsely low).
- Genetically determined protein C deficiency – homozygous/heterozygous protein C deficiency.
- Liver disease, unspecified
- Vitamin K deficiency
Other indications
- Congenital deficiency of protein S can lead to thromboembolic complications in early childhood!