MRX Free Protein S (FPS) is a latex immunoassay for quantitative determination of free protein S in citrated human plasma. Inherited and acquired protein S deficiency is an important risk factor for deep vein thrombosis (DVT) and pulmonary embolism (PE). Measurements of free protein S can detect more subtypes of protein S deficiency than measurements of total protein S and has therefore become an important tool in clinical thrombosis investigations. MRX Free Protein S consists of two different protein S specific antibodies coupled to sub-micron sized polystyrene particles. The system is not sensitive to protein S bound to C4BP, and therefore only reacts with free protein S.
MRX Free Protein S includes two different products designed to match different measuring instruments. For instruments operating in the blue wavelength range (400–600 nm) Nordic Biomarker offers MRX Blue Free Protein S. For instruments operating in the red wavelength range (600–800 nm) Nordic Biomarker offers MRX Red Free Protein S.