The effect of sequestrene and heparin on the erythrocyte sedimentation rate.

The Westergren method for the determination of the erythrocyte sedimentation rate has been conclusively shown to be more reliable than other methods (Gilmour and Sykes, 1951 ; Goldberg, Glynn, and Bywaters, 1952; Lewi and Clarke, 1954; Alexander and Andrews, 1957; Eastham, Denson, and Evans, 1958). Blood for a variety of haematological and biochemical investigations is commonly collected into Wintrobe oxalate mixture, heparin, or sequestrene (ethylenediamine tetra-acetic acid), as anticoagulant. The use of such blood samples for determining the erythrocyte sedimentation rate obviates the necessity of collecting a separate specimen. Rourke and Plass (1929) have shown by the addition of heparin to haemophilic blood that heparin itself has no effect on sedimentation when used at a concentration of 20 units/ ml. but that an excessive amount increases the sedimentation rate. Both heparin and oxalate when used as anticoagulants in determining the E.S.R. have been shown to give anomalously low one-hour readings. These low readings have been abolished and greatly increased readings obtained by the addition of 3.8% sodium citrate as used in the standard Westergren method (Goldberg et al., 1952; Lewi and Clarke, 1954). In these cases the addition of sodium citrate produces three effects: (1) Lowering of the packed cell volume by simple dilution; (2) further lowering of the P.C.V. due to cell shrinkage by the hypertonic sodium citrate; (3) dilution of the plasma proteins. Effects (1) and (2) increase the sedimentation rate since this is inversely proportional to the P.C.V. (Meyers, Trevorrow, Washburn, and Mugrage, 1953; Lawrence, 1953) and outweigh the effect of (3) which decreases the sedimentation rate (Fathraeus, 1929; Lewi and Clarke, 1954). The effect of sequestrene on erythrocyte sedimentation has not been investigated. Ham and Curtis (1938) and Martensson and Hansen (1953) have demonstrated that the addition of oxalate mixture to citrated blood has no effect on the E.S.R. The present investigation was undertaken to evaluate the effect of sequestrene on erythrocyte sedimentation, and to compare the effect of the addition of 3.8% sodium citrate to blood which had been collected into heparin or sequestrene with citrated blood as used in the standard Westergren method.