Latex-based liquid components for quantifying free Protein S in human citrated plasma using readers with wavelengths 600-800nm.

MRX FPS consists of sub-micron sized polystyrene particles coupled to two different monoclonal antibodies specific for protein S. This system is not sensitive to protein S bound to C4b-binding protein, but only reacts with the free active form of protein S. When the reagent is exposed to a plasma sample containing free Protein S, the particles will agglutinate, giving rise to increased light-scattering. MRX FPS is suitable for automatic coagulation and clinical chemistry instruments using turbidimetric detection in the 600 – 800 nm wavelength range.

Latex based assay

High precision

Specific for free protein S

Good correlation to existing Free Protein S assays

Liquid reagent, ready to use


General Description

Inherited and acquired protein S deficiency is an important risk factor for venous thrombosis. Measurements of free protein S can better discriminate between the different subtypes of Protein S deficiency than what measurement of only total protein S concentrations can and has therefore become an important tool in clinical thrombosis investigations.

Performance Characteristics

MRX FPS is used for quantitative determination of FPS in human plasma. Quantitative determination of FPS in human plasma is used in clinical investigations of different diseases, e.g acquired Protein S deficiency which can be caused by several disorders and treatments. Protein S is a vitamin K dependent glycoprotein with anticoagulant properties and in the presence of calcium, Protein S

acts as a cofactor to and forms a complex with activated protein C (APC). The complex adheres to negatively charged phospholipid membranes which increases the anticoagulant activity of APC. The normal total concentration of Protein S in human plasma is in the range 20 – 25 mg/L; approximately two thirds of this is bound to C4b-binding protein (C4BP), whereas the remaining non-bound fraction is FPS.

Sensitivity & Specificity

Details & Typical Data, MRX153

Product form: Liquid components
Wavelength: 600-800 nm
Interfering substances: No interferences with UF and LMW Heparin <100 U/mL, Bilirubin < 0,8 g/L, Triglycerides <30 g/L, Hemoglobin <10 g/L

Stability & Storage

Parameters MRX153
Storage: 2-8 °C
Shelf life: 18 months from manufacturing date at 2-8 °C
Open vial stability: 4 weeks at 2-8 °C / 4 weeks at 2-25 °C

Ordering Information

Reference Number Product Description Pack Size
MRX153 Free Protein S Latex Reagent 3 x 2.5 mL Reaction Buffer 3 x 4 mL
MRX1206 FPS Calibrator 1x1 mL
MRX181/182/183 Eximius Control Plus, L1/L2/L3 10x1 mL pack per level

MRX FPS product line

Item & description
Pack size


600-800 nm FPS Kit

3x2,5 mL Latex
3x4 mL Reaction Buffer


Sample Diluent (0,9% NaCl) for purpose of dilution of test plasmas and calibrator plasmas for the Fib Clauss, Antithrombin and D-Dimer assays.

10x8 mL


Diluent, for purpose of reconstitution of lyophilised coagulation reagents and controls, where water of a high purity grade is required and the addition of 4 mM NaN3 is not disturbing.


10x2 mL (GHI154-2)

10x4 mL (GHI154-4)

10x5 mL (GHI154-5)

10x10 mL (GHI154-10)


Eximius Control PLUS Triple Set

4x1 mL L1
4x1 mL L2
2x1 mL L3


Eximius Control PLUS L1

10x1 mL


Eximius Control PLUS L2

10x1 mL


Eximius Control PLUS L3

10x1 mL


Scandinavian Multi Control PLUS, abnormal

10x1 mL


Scandinavian Multi Control PLUS, normal

10x1 mL

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