Correlation between turbidimetric and nephelometric methods of measuring C-reactive protein in patients with unstable angina or non-ST elevation acute myocardial infarction

Abstract

Inflammation plays an important role in the atherosclerotic process 1 , and C-reactive protein (CRP) as an index of low-grade inflammation has been established as an independent predictor of cardiovascular events both in healthy individuals 2 and in patients with acute coronary syndromes (ACS) 3 . In stable individuals, values of CRP exceeding 0.3 mg/ dL are associated with a high risk of cardiovascular events 4 . Therefore, a highly sensitive method, such as nephelometry, is necessary to discriminate among such low values of CRP. During ACS, an augmentation of inflammatory activity takes place, and the distribution of CRP values shifts upward 5 . Therefore, turbidimetry, although typically less sensitive than nephelometry, has the potential to be useful in such a patient population.To evaluate the performance of the turbidimetric method of CRP as an index of low-grade inflammation in subjects with ACS, we correlated measurements by turbidimetry with measurements by nephelometry, both performed on the same plasma samples from patients with unstable angina or non-ST elevation acute myocardial infarction. MethodsPatients admitted to the coronary care unit of our hospital because of unstable angina or non-ST elevation acute myocardial infarction between December 2000 and January 2002 were evaluated as study candidates. Inclusion criteria were defined as onset of chest discomfort in the prior 48 hours in patients with ECG changes consisting of transient ST-segment depression (≥0.5mm) or T wave inversion (≥1.0mm), and/or positive troponin I (>1.0ng/dL). Infarction at admission was defined by a positive troponin test. Patients with infarction and ST-segment elevation or left bundle-branch block were not included. Objective -To evaluate the performance of the turbidimetric method of C-reactive protein (CRP) as a measure of low-grade inflammation in patients admitted with non-ST elevation acute coronary syndromes (ACS). Methods -Serum samples obtained at hospital arrival from 68 patients (66±11 years, 40 men), admitted with unstable angina or non-ST elevation acute myocardial infarction were used to measure CRP by the methods of nephelometry and turbidimetry. Results -

Use of C‐reactive protein as a predictor of chorioamnionitis in preterm prelabour rupture of membranes: a systematic review

“…There are several laboratory techniques to measure CRP including nephelometry, turbidimetry and radial immunodiffusion or electroimmunodiffusion. The studies included in this review that described the CRP method used either nephelometry or turbidimetry, which seem to correlate well 24 . Although some interlaboratory variation may be expected, this is unlikely to be of clinical significance.…”

“…The studies included in this review that described the CRP method used either nephelometry or turbidimetry, which seem to correlate well. 24 Although some interlaboratory variation may be expected, this is unlikely to be of clinical significance. Highsensitivity CRP (hs-CRP) test is a novel type of CRP, which has significantly lower limits of detection (range 0.5-10 mg/l) and is most often used to help predict a healthy person's risk of cardiovascular disease.…”

Site-directed immobilisation of antibody fragments for detection of C-reactive protein

“…If CRP is higher than 3 mg/l, a person is at high risk of developing cardiovascular disease, the risk is average between 1 and 3 mg/l and below 1 mg/l the risk is low (Kushner and Sehgal, 2002). CRP is nowadays diagnosed with tests like enzyme-linked immunoassay, nephelometric and turbidimetric assays (Correia et al, 2003). As new detection methods piezoelectric microcantilevers (Lee et al, 2004, Wee et al, 2005 and a microfluidic network (Wolf et al, 2004) has been demonstrated.…”

Comparison Of Immunonephelometric And Immunoturbidimetric Methods for Measuring Beta 2-Microglobulin: Fit for Purpose in Routine Clinical Laboratories

“…There are many studies in the literature which compared the results of different spesific proteins, such as CRP, IgA, IgG, IgM, C3, C4, haptoglobin, transferin, apolipoproteins, RF etc. held by nefelometric and turbidimetric methods, and results of two methods were found to be correlated with each other [21,[28][29][30][31][32]. Correia et al [28] found that CRP levels measured by either methods were correlated with each other, in both unstable angina patients and in patients with non-ST elevation acute myocardial infarction.…”

“…held by nefelometric and turbidimetric methods, and results of two methods were found to be correlated with each other [21,[28][29][30][31][32]. Correia et al [28] found that CRP levels measured by either methods were correlated with each other, in both unstable angina patients and in patients with non-ST elevation acute myocardial infarction. In Dominici et al [30] study, the two systems were found to perform substantially equally, both in hsCRP and in CRP measurement; but in the hsCRP assay, the precision of nephelometry (CV% in the interval 3.0-5.8) was lower than that of turbidimetry (CV% in the interval 1.8-2.3).…”