Eurofins Biomnis code

PSLI

Synonyms

• Free protein S antigen
• Free PS Ag

Specialty

Haematology

Clinical significance

The protein S assay forms is part of the thrombophilia assessment. A free protein S antigen assay is performed when the activity assay is reduced, in order to specify the type of protein S deficiency. A cofactor of activated protein C, protein S ("PS") is a physiological inhibitor of coagulation. It accelerates the inactivation rate of factors Va and VIIIa. It is synthesised by the liver and is vitamin K-dependent. PS circulates in a free, functional form (40%) and an inactive form linked to C4bBP (60%). Congenital PS deficits can be quantitative and qualitative. These deficits are passed on by autosomally dominant transmission and are manifested by recurrent thrombosis. Acquired PS deficits in appear in the context of hepatic insufficiency, treatment with vitamin K antagonists, drugs (oral contraceptives), diabetes, inflammation (increased C4bBP), pregnancy. The free protein S antigen assay should be performed at least 2 to 3 weeks after discontinuation of treatment with vitamin K antagonists and after any thrombotic episode has subsided.

Preanalytics

• 1 mL :
• Citrated Plasma
•   FROZEN
• Freezing within 4 hours

• A tube specifically for this analysis : Yes

Further information

Enclose the specific clinical information form (R5-INTGB : Haemostasis)
Attach the clinical data relating to the patient (major inflammatory syndrome, pregnancy, etc.) and the circumstances (bleeding, thrombosis, preoperative evaluation, possible anticoagulant treatment.)
[To be translated]
It is advisable to send us a frozen and centrifuged citrate sample in compliance with the GFHT pre-analytical recommendations.

Documents to download

• Specific clinical information form (R5-INTGB)

Methodology

Immuno turbidimetry

Turnaround time

2 days