Erythrocyte Sedimentation Rate Measurements by TEST 1 Better Reflect Inflammation Than Do Those by the Westergren Method in Patients With Malignancy, Autoimmune Disease, or Infection

Choong-Hwan Cha, MD; Chan-Jeoung Park, MD, Young Joo Cha, MD; Hyun Kyung Kim, MD; Duck Hee Kim; Honghoon; Jae Hoon Bae; Jae-Seol Jung; Seongsoo Jang, MD; Hyun-Sook Chi, MD; Dong Soon Lee, MD; Han-Ik Cho, MD

Disclosures

Am J Clin Pathol. 2009;131(2):189-194. 

In This Article

TEST 1 Method

The TEST 1 analyzer, a closed automated analyzer, determines the length of sedimentation reaction in blood in a standard-size primary tube with a perforating stopper. The principle of measurement is the study of the aggregation capacity of RBCs by telemetry. The tubes are placed in appropriate racks, and their contents are rotated slowly for about 2 minutes. The sample loader simultaneously accepts 4 racks containing 15 tubes each. By using a closed aspiration needle, the blood is directly drawn from the collection tube, distributed in a capillary, and centrifuged at about 20g. The sensing area temperature is maintained at 37°C. The system uses an infrared ray microphotometer with a light wavelength of 950 nm and performs 1,000 readings during 20 seconds. The electrical impulses, collected using a photodiode detector, are directly correlated to the aggregation of RBCs present at each capillary level. For each sample, an aggregation and sedimentation curve is obtained. A mathematical algorithm converts the raw data obtained from evaluation of optical density signals into ESR results, which are transformed to comparable Westergren values. The system operates at a rate of 180 specimens per hour in continuous loading, providing a result every 20 seconds, and requires 150 µL of blood for each sample.[3,5,6,8]

Measurement of Inflammatory Plasma Proteins

Total protein, albumin, and CRP concentrations in each plasma sample were measured at Seoul National University Hospital, Seoul, Korea. The globulin concentration was calculated by subtracting the albumin from the total protein concentration. The fractions of albumin and α1-, α2-, β1-, β2-, and γ-globulin were measured by capillary electrophoresis.

Statistical Analysis

We compared the correlations of Westergren and TEST 1 ESR values with the concentration of each inflammatory plasma protein. All statistical analyses were performed using SPSS 13.0 software (SPSS, Chicago, IL) and MedCalc, version 9.5.2.0 (Mariakerke, Belgium). The correlations of TEST 1 data and those of the Westergren method were evaluated by linear regression and paired t tests. Data were also compared by using Bland-Altman analysis.[9] Accuracy was assessed by determining 95% confence intervals for the mean differences between methods. Linear regression was used to estimate correlations between ESR measurements and the concentration of each plasma protein. P values less than .05 were consered statistically significant.

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