Differences in erythrocyte sedimentation rates using a modified Westergren method and an alternate method.

INTRODUCTION: Worldwide laboratories have adopted the use of modified or alternate methods for measurement of the erythrocyte sedimentation rate (ESR). The iSED from Alcor Scientific is a novel, alternate ESR method based on photometric aggregometry which offers improved operator safety and reduced analysis time. This study evaluated the diagnostic utility of the iSED in a South African patient population with a range of inflammatory disorders. METHODS: We compared the iSED with the predicate modified Westergren method (StaRRsed, Mechatronics, Zwaag, the Netherlands) measured at 60 minutes. Analysis was performed on K2 EDTA samples at three ESR measurement ranges (<20, 20-80 and >80 mm/h) in 120 pediatric and adult inpatients and outpatients over a 2-week period. Precision, stability, and carryover were performed in accordance with the revised International Council for Standardisation in Haematology guidelines. RESULTS: The iSED demonstrated acceptable imprecision with minimal carryover (2.86%). The correlation coefficients at the 3 ESR measurement ranges were r = 0.58, r = 0.71, and r = 0.56, respectively. The y-intercepts were -10.74 (CI -29.17 to 7.69), -5.95 (CI -18.60 to 6.69) and 246.05 (CI 591.42-99.31). This indicated a difference of a constant nature with an overall mean difference of 7.99 mm/h (CI 5.87-10.13) (P < 0.001). iSED ESR measurements were stable up to 24 hours when stored at room temperature or at 4-8°C. CONCLUSION: This study demonstrated differences in ESR results, predominantly at extremes of the analytical range, using an alternate method. Careful consideration and performance monitoring of these novel methods are advised.

Erythrocyte sedimentation rate measured using microhemagglutination is not elevated in monoclonal gammopathy compared with other diseases.

BACKGROUND: The erythrocyte sedimentation rate (ESR) as measured using the Westergren method is extremely elevated in patients with monoclonal gammopathy (MG) owing to the abundance of positively charged paraproteins. However, it has not been determined if the ESR is likewise high in patients with MG when measured using alternate ESR methods. METHODS: The ESR was measured using both the modified Westergren and microhemagglutination method (TEST1) in 36 patients with MG and in 159 individuals with other diseases. RESULTS: Erythrocyte sedimentation rates measured by the Westergren vs microhemagglutination methods showed substantial, but not remarkably high correlation. ESR measured using the Westergren method was higher in MG than in non-MG patients; however, ESR measured using microhemagglutination was not different in the 2 groups, resulting in a larger ΔESR (microhemagglutination ESR-Westergren ESR) in MG patients. When considered as continuous variables, none of the tested interfering plasma proteins (C-reactive protein, globulin, or fibrinogen) showed substantial correlations with Westergren or microhemagglutination ESRs. MG and low hematocrit were the only factors independently associated with ΔESR on multivariate analysis. CONCLUSION: We demonstrated, for the first time, that the ESR as measured by microhemagglutination is not elevated in patients with MG compared with those without. The ESR does not correlate with a particular plasma protein, showing that its measurement is multifactorial. The presence of MG is an independent factor for ΔESR.