ABSTRACT
BACKGROUND: Determination of the length of sedimentation reaction in blood (LSRB) is frequently used in daily practice to assess disease intensity. Recently, a micro-sedimentation method was introduced (TEST 1) that uses EDTA anti-coagulated blood samples. The aim of this study was to characterize this method by comparing it to a conventional Westergren method (Sedimatic 100). Furthermore, correlation between fibrinogen and the LSRB and the influence of M-proteins on the LSRB was investigated. METHODS: Unselected paired samples were used for comparison between the TEST 1 and Sedimatic 100 methods (n=733); fibrinogen was measured in EDTA samples (n=765) using a turbidimetric method. Furthermore, LSRB was measured in 29 EDTA samples in paired serum tubes from patients in whom an M-protein was detected. RESULTS: TEST 1 showed excellent correlation with the Sedimatic 100 method (y=1.00x; n=733; r=0.92, 95% CI 0.90-0.93; p<0.0001), and had no significant bias (0.15 mm/h, 95% CI -0.48 to 0.75 mm/h). Furthermore, TEST 1 LSRB showed satisfactory correlation with the fibrinogen content (y=3.13+0.06x; n=765; r=0.78, 95% CI 0.75-0.80; p<0.0001). In samples containing M-proteins, satisfactory correlation between the M-protein content and TEST 1 LSRB was found (y=0.69+0.22x; n=29; r=0.71, 95% CI 0.45-0.85; p<0.0001), while excellent correlation was found when only M-proteins of the IgM type were taken into account (y=-0.95+0.23x; n=9; r=0.93, 95% CI 0.71-0.99; p<0.0002). CONCLUSIONS: The results confirm previous reports that TEST 1 is a reliable method to measure the LSRB, and shows for the first time the quantitative relationship between TEST 1 LSRB and M-proteins, particularly those of the IgM type.
Subject(s)
Fibrinogen/analysis , Glycoproteins/blood , Hematologic Tests/methods , Nephelometry and Turbidimetry/methods , Blood Sedimentation , Humans , Time FactorsABSTRACT
Ongoing demands on laboratory performance require optimization of processes. An obvious way to achieve this is to reduce manual labor in favor of automated methods. We describe the validation of an automated quantitative urine human chorionic gonadotropin (hCG) analysis on the Roche Modular E170 analyzer to replace the manual qualitative pregnancy test in urine. At urine hCG concentrations of 476, 45 and 11 U/L, we found inter-assay variation of 4.3%, 4.3% and 6.8% and average intra-assay variation of 3.0%, 2.6% and 3.0%, respectively. The analytical detection limit was 0.7 U/L. We did not detect any loss (due to degradation or adsorption) during a storage period of 5 days at 4 degrees C or at -20 degrees C. Recoveries of hCG in urine of a pregnant woman diluted with urine of a pre-menopausal non-pregnant woman (concentration range between 6 and 800 mU/L) were between 93% and 112% (y=0.997x-3.843, r 2 =0.999). Diluting a serum sample (hCG 42,000 U/L) with urine (negative for hCG) up to 8000-fold yielded a completely linear hCG response, indicating that the assay was not affected by the urine matrix. In a correlation study with 60 urine samples (of which 10 were of male origin), we did not find any discrepancies between results for the manual pregnancy test and the hCG test on the Roche Modular E170 (using a cutoff value of 50 U/L).
