Order Code
3545
Preferred Specimen
Collect 2 mL of serum. Allow the SST tube to clot upright for at least 30 minutes, then centrifuge within 2 hours after collection. Keep the specimen refrigerated.
Container Type
Serum Separator Tube
Alternate Specimen Requirements
Acceptable alternatives include:
Collect 2 mL of serum using a plain red top tube. Allow it to clot upright for at least 60 minutes, then centrifuge and transfer the serum to a plastic transport tube within 2 hours. Make sure to label the tube clearly as serum from a plain red top tube. Keep refrigerated.
Minimum Volume
- Adult: 0.5 mL serum
- Pediatric: 0.2 mL serum (insufficient for repeat or additional testing)
Transport Temperature
Refrigerated
Expected Turnaround Time
1–2 days
Specimen Stability
- Room temperature: 1 week
- Refrigerated: 1 week
- Frozen: 1 month
Rejection Criteria
Gross hemolysis
Methodology
Roche COBAS particle enhanced immunoturbidimetric, Gen 4
Overview
C-reactive protein (CRP) is an acute phase reactant (APR) produced by the liver, which begins to rise in the blood just a few hours after inflammation starts. Although CRP is a sensitive marker for acute injury, infection, or inflammation, it is not specific to any one disease. Elevated CRP levels can be seen in myocardial infarction, sepsis, cancer, autoimmune conditions, and after surgery.
Since its discovery in 1965, CRP has served as a valuable tool for assessing inflammation. Recent epidemiologic studies have also shown a link between high CRP levels and an increased risk of coronary heart disease (CHD). (See High-Sensitivity C-Reactive Protein.)
Clinical Significance
- Used for detecting and monitoring inflammation, similar to the erythrocyte sedimentation rate (ESR).
- Acts as a nonspecific marker of inflammation, often used in routine screening for ill patients.
- Helps detect infections and evaluate the response to antibiotic therapy in bacterial infections.
- Postoperative monitoring:
- CRP levels start rising within 4–6 hours after surgery, peaking around 2–3 days.
- Elevated postoperative CRP beyond the expected range may indicate infection or inflammation.
- Serves as a risk factor for cardiovascular disease — individuals with higher baseline CRP are at greater risk for CHD and stroke. (See High-Sensitivity C-Reactive Protein, Serum or Plasma.)
- Useful in detecting, assessing severity, and monitoring inflammation in various conditions such as:
- Myocardial infarction
- Pelvic inflammatory disease (PID)
- Sepsis (particularly in critically ill patients)
- Acute appendicitis
- Transplant rejection
Interpretative Information
A CRP level below 10 mg/L is generally considered the upper limit of normal. Values ≥10 mg/L may suggest the presence of an active inflammatory process.
Limitations
- CRP reflects inflammation but is nonspecific, so results should be interpreted in the context of clinical findings.
- Lipemia or hemolysis can lead to false-positive results.
- Oral contraceptive use may cause mild CRP elevation without inflammation (van Rooijen, 2006).
References
Gambino R. C-reactive protein – undervalued, underutilized. Clin Chem. 1997; 43(11):2017–2018. 9365383
Hallan S, Asberg A, Edna TH. Additional value of biochemical tests in suspected acute appendicitis. Eur J Surg. 1997; 163(7):533–538. 9248988
Hutchinson WL, Koenig W, Frohlich M, et al. Immunoradiometric assay of circulating C-reactive protein: age-related values in the adult population. Clin Chem. 2000; 46(7):934–938. 10894836
Ishii S, Karlamangla AS, Bote M, et al. Gender, obesity and repeated elevation of C-reactive protein: data from the CARDIA cohort. PLoS One. 2012; 7(4). Epub 2012 Apr 30. 22558327
Ledue TB, Rifai N. Preanalytic and analytic sources of variations in C-reactive protein measurement: implications for cardiovascular disease risk assessment. Clin Chem. 2003; 49(8):1258–1271. 12881440
McPherson RA, Pincus MR. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, PA: Saunders; 2007.
Mosca L. C-reactive protein – to screen or not to screen? N Engl J Med. 2002; 347(20):1615–1617. 12432050
Pearson TA, Mensah GA, Alexander RW, et al. Markers of inflammation and cardiovascular disease. Circulation. 2003; 107:499–511. 12551878
Povoa P, Almeida E, Moreira P, et al. C-reactive protein as an indicator of sepsis. Intensive Care Med. 1998; 24(10):1052–1056. 9840239
Relijic M, Gorisek B. C-reactive protein and the treatment of pelvic inflammatory disease. Int J Gynaecol Obstet. 1998; 60(2):143–150. 9509952
van Rooijen M, Hansson LO, Frostegård J, et al. Treatment with combined oral contraceptives induces a rise in serum C-reactive protein in the absence of a general inflammatory response. J Thromb Haemost. 2006; 4(1):77–82. 16409455
Visser M, Bouter LM, McQuillan GM, et al. Elevated C-reactive protein levels in overweight and obese adults. JAMA. 1999; 282(22):2131–2135. 10591334
Test Setup Days
Monday through Friday PM shift
CPT
86140 LOINC: 1988-5
Reference Range
<0.5 MG/DL
| UNIT CODE | UNIT CODE NAME | ANALYTE | GENDER | AGE | REFERENCE RANGE | Units of Measure |
|---|---|---|---|---|---|---|
| 3545 | CRP | CRP | NOT SPECIFIED | ALL | <0.5 | MG/DL |
| 3545 | CRP | CRP | MALE | ALL | <0.5 | MG/DL |
| 3545 | CRP | CRP | FEMALE | ALL | <0.5 | MG/DL |