Sodium citrate is the anticoagulant of choice for studies of platelet function and morphology. The standard concentration is 1 part 3.8% solutions to parts of blood, (Schalms; 2006) . For coagulation studies a volume of blood is added to 1 volume of 109mmo1/l sodium citrate solution (Ingram and Hills 1976). For erythrocyte sedimentation rate (ESR), 4 volumes of blood are added to 1 volume of the sodium citrate solution (109mmol/L) and immediately mixed with it (international committee for standardization in haematology: 1977). These are some
of the uses of sodium citrate.
Disadvantages of Sodium Citrate;
1. It interferes with many chemical tests
2. It has a tendency to shrink cells
3. Because of a 10% dilution of blood, sodium citrate is generally not used for complete blood count (CBC) (Schalms; 2006)
For many years, citrate was the anticoagulant preferred by most investigators undertaking platelet studies (Zelmanovic et al, 1998), this is mainly because sodium citrate causes less spontaneous activation of platelets in vitro but EDTA does (Golanski et al; 1996). a high concentration of sodium citrate in blood samples decreases plasma concentration of ionized calcium resulting in reduced platelet aggregation and fibrinogen binding. (Am Jvet Res; 2001). When blood is collected into citrate, there is initially little or no change in platelet shape and volume, however in citrate, platelets adopt a spherical shape and volume, however in citrate, platelets adopt a spherical shape (Macey et al, 1999) and as in EDTA, swell progressively over a period of 1 – 2 hours (3-10% increase in volume by impedance procedures, depending on the concentration of sodium citrate used (Threatte el al; 1984; Bath; 1993 and Jackson and Carter, 1993) . citrate-base anticoagulants have been used for their determination of platelet indices in the ADVIA 120 (Macey et al 1999 and Zelmanovic et al 1998) they suggested that platelet sphering may not be essential for the analysis. As cited from (Clin Lab, 1990 ) analysis of the mean platelet volume (MPV) showed significant lower values in the citrated samples as compared to the same examples in EDTA.
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