High-sensitivity C-reactive protein in clinical practice: analytical methods and some aspects of its diagnostic significance

Ruskovska, Tatjana (2011) High-sensitivity C-reactive protein in clinical practice: analytical methods and some aspects of its diagnostic significance. In: 19th Meeting of Balkan Clinical Laboratory Federation, 21 – 23 September 2011, Bucharest, Romania.

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Abstract

Introduction. C-reactive protein (CRP), discovered in 1930, historically has been used only to detect and predict the outcome of various infectious, inflammatory and necrotic processes and to assess the efficacy of treatment of those processes. As it became clear that all stages of atherosclerosis might be considered as an inflammatory response to injury, CRP in its reference values (up to 10mg/L) arose as one of the “emerging risk factors” for cardiovascular disease. Measurement of its plasma concentrations by high-sensitivity analytical methods, in the absence of an overt infective or inflammatory episode, has been proven to have a predictive value for first coronary heart disease event. Moreover, recent studies point hsCRP (high-sensitivity C-reactive protein) as a marker for all-cause mortality in general population and patients on hemodialysis.
Materials and Methods. Because of the wide diagnostic significance of hsCRP, different methods for its accurate measurement were developed. The aim of this study was to compare the results obtained by immunoturbidimetric and immunochemiluminiscent method. Furthermore, the immunoturbidimetric method was used to assess the predictive value of hsCRP for all-cause mortality in patients on chronic hemodialysis treatment.
Results and Discussions. hsCRP was measured in total of 61 random serum samples, within and above reference value, by immunoturbidimetric (Beckman Coulter, AU400 analyzer) and immunochemiluminiscent (Siemens, Immulite analyzer) method. Excellent correlation was found between methods: r=9986; regression analysis: АU400=0,904 Immulite - 0,100. Except for values below 1mg/L where immunochemiluminiscent method gave in average slightly lower results (n=17; 0,52±0,26 : 0,54±0,25; p<0,05; r=0,9903; АU400=0,941 Immulite + 0,051), for all other ranges of diagnostic significance: 1-3mg/L (n=24; 1,87±0,61 : 1,73±0,50; p<0,001; r=0,9860; АU400=0,812 Immulite + 0,211), 3-10mg/L (n=10; 5,14±1,10 : 4,21±0,82; p<0,001; r=0,9502; АU400=0,702 Immulite + 0,596) and above 10mg/L (n=8; 43,48±28,32 : 39,03±26,14; p<0,01; r=0,9965; АU400=0,920 Immulite - 0,965) results obtained by immunochemiluminiscent method were in average slightly higher (below mentioned samples excluded). Anyway, because of this difference, only two patients with borderline hsCRP values would be ranged in higher range of diagnostic significance by immunochemiluminiscent method (immunoturbidimetric : immunochemiluminiscent – 1. 1,00 : 1,06; 2. 9,20 : 12,10).
Thus, even working consistently with all principles of good laboratory practice, a slight difference between studied analytical methods for hsCRP has been observed. Although ranges of diagnostic significance of hsCRP are well established, in practice, especially when working with different analytical methods, a special care must be taken for patients with borderline values, in order to avoid erroneous risk assessment.
Further, the Beckman Coulter’s immunoturbidimetric method was used to assess the predictive value of hsCRP for all-cause mortality in patients on hemodialysis. Serial hsCRP measurements approach was used and the lowest of four measurements was taken as basal. Based on their basal hsCRP values all 60 patients included in the study were divided in three groups:
1. basal hsCRP < 1mg/L (n = 26; mean age 57±12 years, range from 34 – 77 years; mean duration of hemodialysis 8±7 years, range from 2 – 28 years),
2. basal hsCRP from 1 to 3mg/L (n = 18; mean age 62±10 years, range from 44 – 79 years; mean duration of hemodialysis 7±6 years, range 1 – 19 years),
3. basal hsCRP > 3mg/L (n = 16; mean age 66±9 years, range from 53 – 78 years; mean duration of hemodialysis 9±7 years, range from 2 – 29 years).
After two years of follow-up the all-cause mortality rates were: 1. 3,8%, 2. 27,8% and 3. 37,5% respectively, with statistical significance of lower mortality rate observed for the first group (p<0,25).
Very low mortality rate within the two years study period among the patients on chronic hemodialysis treatment with basal hsCRP lower than 1mg/L confirms that these are “safe hsCRP values” associated with very low risk of all-cause mortality independently of age, duration of hemodialysis and co-morbidities.
Conclusions. Recent evidences about diagnostic significance of CRP, especially of its low concentrations determined by high-sensitivity methods, ensure a promising future for this humble, but powerful protein biomarker.

Item Type:	Conference or Workshop Item (Lecture)
Subjects:	Medical and Health Sciences > Clinical medicine
Divisions:	Faculty of Medical Science
Depositing User:	Tatjana Ruskovska
Date Deposited:	24 Nov 2012 12:58
Last Modified:	24 Nov 2012 12:58
URI:	https://eprints.ugd.edu.mk/id/eprint/1898

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