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Protein S
Plasma
Test performed by: LabPLUS Coagulation
Test performed by the Coagulation laboratory(
Ext 22069
).
For results, use ward computer or phone
Lablink
:
22000
or
(09) 307-8995
or
0800 522 758
.
This test is included in a
Thrombophilia Screen
Specimen Collection
2.7 mL Citrate Bloodor
1 mL Paediatric 2xCitrate Blood
-
Tube must be adequately filled.
Referral Laboratories:
Please separate the specimen and send minimum 1.0 ml platelet poor plasma to LabPlus frozen.
1.8 mL 2xCitrate Bloodor
Reference Intervals
Units: %| Age Range | Either Sex |
|---|
| >= 3 m | 65 - 110[1] |
[1]
For paediatric reference range information, contact a paediatric Haematologist.
-
Uncertainty of Measurement:
10%
-
Reference Interval is for a Functional Protein S Assay.
Neonate: adult levels reached by 3 - 6 months
Turnaround Time: Within 2 weeks
Diagnostic Use and Interpretation
- Protein S is a vitamin K dependent anticoagulant protein synthesised in liver and endothelial cells. It circulates in plasma alone (free) or reversibly bound to C4b binding protein (total). Only free protein S has anticoagulant activity.
- Free Protein S is a cofactor for activated Protein C (APC) in inactivating activated factors (Va and VIIIa). A low functional result should be confirmed on a repeat sample.
Contact Information
For further information contact the
Haematology laboratory (Ext 22067)
or:
|
Dr Nicola Eaddy
|
Ext 22005
|
|
|
Dr Peter Bradbeer
|
Ext 22062
|
|
|
Dr Anna Ruskova
|
Ext 22137
|
|
|
Dr Nikhil Rabade
|
Ext 22071
|
Result Details
Acquired Protein S deficiency occurs in many conditions e.g. vitamin K deficiency, oral anticoagulant therapy, or use, liver disease, DIC, TTP, acute inflammatory events (raised C4bP), nephrotic syndrome, sickle cell anaemia. Oral contraceptive use and pregnancy can drop levels markedly (as low as 20%). The clinical significance is unclear.
Patients with congenital Protein S deficiency have an increased risk of thrombosis occurring mainly in 15 - 40 yr. age group (50% by age 50). Typically, free Protein S is decreased (30 - 40%) with total Protein S low normal or decreased. It can be difficult to confirm a deficiency if a co-morbid condition is present.
Caution:
Not useful for predicting thrombotic events.
Falsely low levels may occur if PR is shortened. e.g. in the presence of activated samples, high F VIII or APC resistance.
See:
Protein C
Thrombophilia Screen
and
Protein C
Last updated at 13:09:28 11/09/2024