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C-REACTIVE PROTEIN (CRP) TEST
PRECAUTIONS LIMITATIONS OF THE PROCEDURE RapidTex CRP Latex Test 1. For in-vitro Diagnostic Use Only. 1. The strength of the agglutination reaction is not indicative of the 2. The preservative sodium azide may react with metal plumbing to CRP concentration. Weak reactions may occur with slightly INTENDED USE from explosive metal oxides. In disposal, flush with a large a elevated or markedly elevated concentrations. The RapidTex CRP Latex Test is intended to be used for the qualitative volume of water to prevent metal azide build up. 2. A prozone phenomena (antigen excess) may cause false negatives. and semi-quantitative detection of C-reactive protein (CRP) in human 3. Human control sera were tested for the presence of Hepatitis B It is advisable, therefore, to check all negative sera by retesting at a serum. Surface Antigen (HBsAg) and anti-HIV antibody and found to be 1:10 dilution. negative. However, all materials should still be handled as 3. Reaction times longer than specified may produce apparent false SUMMARY infectious agents. reactions due to a drying effect. CRP usually appears in the sera of patients in the acute stages of a 4. Strongly lipemic or contaminated sera can cause false positive number of inflammatory conditions such as most bacterial and some SPECIMEN COLLECTION AND HANDLING reactions. viral infections; acute rheumatoid fever with or without carditis; Fresh patient serum specimen should be used in the testing. If testing 5. Only serum should be used in this test. rheumatoid arthritis and most other collagen diseases; and in a number of cannot be performed after collection, specimen should be kept other conditions characterised by inflammation. CRP is considered to be refrigerated. If testing is to be prolonged in excess of 24 hours, serum EXPECTED VALUES a sensitive indicator of inflammation. Changes in the serum level of should be frozen. Bacterial contamination may cause protein Normal adult levels of CRP are reported to be less than 12 mg/L. Trace CRP with time from the same patient can be used as an index of denaturation. Strongly lipemic sera and/or bacterial contamination may levels of CRP had been reported in the sera of apparently healthy adults3 recovery. The use of the CRP test to measure the effectiveness of cause false positive agglutination. and normal children4. The CRP level can increase significantly (>10 therapy is of great clinical significance in cases such as acute rheumatoid fold) above the normal values with the onset of a substantial fever. TEST PROCEDURE inflammatory stimulus. PRINCIPLE Method I (Qualitative) PERFORMANCE CHARACTERISTICS The RapidTex CRP Test is based on the latex-agglutination method 1. Bring all reagents, controls and serum samples to room It must be stressed that the latex agglutination technique is more introduced by Singer et al in 1957. The principle of this test is based on temperature. sensitive than precipitation in capillary tubes or in agar gel methods, thus the immunological reaction between CRP as an antigen and the 2. Shake the CRP latex reagent gently before use. Deliver one drop giving positive results at lower CRP levels. The CRP levels in patients corresponding antibody coated on the surface of biologically inert latex of reagent to the test circle. Using the disposable pipettes, add one with strongly positive CRP reactions had been detected as high as 330 particles. drop of the undiluted patient serum onto the same circle and mix mg/L5 while the CRP content of normal serum is less than 12 mg/L6. both together with the paddle end of the pipette. REAGENTS AND MATERIALS SUPPLIED 3. Positive and negative controls should be run with each series of REFERENCES 1. CRP Latex Reagent: Contains polystyrene latex particles coated test serums in the same way as in Step 2. 1. MacCleod CM, and Avery OT: J. Exper. Med. 73, 191, 1950. with anti-human CRP and suspended in buffer and 0.1% sodium 4. Rotate slide back and forth for 2 minutes and read result under an 2. Singer JM, and Plotz CM: Am. J. Med., 21, 888, 1956. azide preservative. Shake well prior to use. indirect oblique light source. 3. Scherffarth F, Perez-Miranda M, and Goetz H: Blut 20, 296, 1970. 2. CRP Positive Control: Human Serum that contains CRP and 0.1% 4. Saxtad J, Nilsson LA and Hanson LA: Acta Paediat. Scand. 59, sodium azide as preservative. Method II (Semi-Quantitative method): 25, 1970. 3. CRP Negative Control: Human Serum that contains 0.1% sodium 1. Set up at least 5 test tubes and label 1:2, 1:4, 1:8, 1:16, 1:32, and 5. Wood HF, and McCarty M: J. Clin. Invest. 30, 616, 1951. azide as preservative. etc. 6. Nilsson LA: Acta Path. Microbiol. Scand. 73, 129, 1968. 4. Glycine Buffer Concentrate (20X): To be diluted 1 part with 19 2. Use diluted Glycine-Saline Buffer to serially dilute sample to be parts distilled water. titered according to standard laboratory practice. 5. Disposable pipettes. 3. Repeat all steps as in Qualitative Method using these new samples. 6. Glass test slide. Genix Technology RESULTS Vancouver, Canada. MATERIALS REQUIRED BUT NOT SUPPLIED Positive reaction is indicated by agglutination. Since negative results Revised May 1992. 1. Serological pipettes. may be caused by antigen excess, the test should be repeated using a 2. Test tubes 12x75 mm. diluted serum sample in case prozone effect is suspected. For the Semi- 3. Timing device. Quantitative Method, multiplication of the dilution factor with 6 mg/L 4. Distilled water. will yield the approximate level of CRP in the serum sample. STORAGE & STABILITY DILUTION CONCENTRATION (mg/L) When not in use, store reagents and controls at 2º to 8ºC. DO NOT 1:1 6 FREEZE. Prior to use, allow reagents and controls to warm up to room 1:2 12 temperature. Biological indication of product instability is evidenced by 1:4 24 inappropriate reaction of the latex reagent with the corresponding 1:8 48 positive and negative control sera.
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