Lab Test: C-Reactive Protein, CRP (Serum) Level
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- Measures serum C-reactive protein (CRP), an acute phase reactant that is a biomarker of inflammation. It is believed to be of value in predicting coronary events.
- Adults: 0.08-3.1 mg/L
- Adults (high sensitivity): 0.02-8 mg/L
- Cardiac risk:
- Low: <1.0 mg/L
- Average:
1.0 to 3.0 mg/L
- High: >3.0 mg/L
- Suspected meningococcemia in children with associated septic shock and purpura - have moderate diagnostic but not prognostic value for meningococcal disease
- Bacterial meningitis - CPR levels may be increased up to 100-fold or more. Most useful for monitoring patient response to therapy after primary diagnosis of invasive infectious or inflammatory disease
- Community-acquired pneumonia - CRP is elevated in about 25% of patients with pneumonia, but it is not helpful in discriminating between viral and bacterial pneumonia in children. May be a useful adjunct for diagnosing Legionella pneumonia. The odds of having a CRP level > 25 mg/dL almost 7 times higher in patients with Legionella infection than in those with pneumonia due to other causes.
- Coronary artery disease - CRP levels > 10 mg/L increase risk of death 4-fold compared with CRP levels < 3 mg/L. A serum CRP concentration above 3 mg/L correlates with a poorer prognosis in patients with unstable angina.
- Rheumatoid arthritis - CRP > 1 mg/dL indicates an inflammatory process but it is nonspecific.
- Serum marker to assess the severity of acute pancreatitis - CRP levels > 150 mg/dL at 48 hours predict disease severity.
- Suspected and known Kawasaki disease - CRP level of 3 mg/dL or greater is found in nearly all cases of Kawasaki disease during the cute febrile stage. CRP > 10 mg/dl have been associated with a poor response to intravenous immunoglobulin.
- Suspected and known malaria - CRP level correlates well with the severity of P falciparium malaria and is useful in following the response to therapy.
- Suspected and known osteomyelitis - CRP elevated in 90% of children with osteomyelitis overall and in almost all patients with vertebral osteomyelitis.
- Suspected appendicitis - CRP elevated in relation to severity of appendiceal inflammation
- Suspected pelvic inflammatory disease (PID) - an elevated CRP level supports the diagnosis of PID Suspected sepsis - CRP level > 2 standard deviations above normal is an indicator of inflammation. CRP is elevated at the onset of infection (greater than 20 mg/L) and will increase during the initial course, then decrease as the patient recovers.
- Acute, noninfectious inflammatory reaction (e.g., arthritis, acute rheumatic fever, Reiter syndrome, Crohn disease)
- Collagen-vascular diseases (e.g., vasculitis syndrome, lupus erythematosus)
- Tissue infarction or damage (e.g., acute myocardial infarction {AMI}, pulmonary infarction, kidney or bone marrow transplant rejection, soft-tissue trauma)
- Bacterial infections such as postoperative wound infection, urinary tract infection, or tuberculosis
- Malignant disease
- Bacterial infection (e.g., tuberculosis, meningitis)
- Increased risk for cardiovascular ischemic events
- Erythrocyte sedimentation rate - nonspecific test used to detect inflammatory, infectious, and necrotic processes.
- Complement assay
- Feibrinogen
- Lipoproteins - important risk factor for heart disease
- Homocysteine - important risk factor for heart disease
- Elevated test results can occur in patients with hypertension, elevated body mass index, metabolic syndrome/diabetes mellitus, chronic infection (gingivitis, bronchitis), chronic inflammation (rheumatoid arthritis), and low high-density lipoprotein (HDL)/high triglycerides.
- Cigarette smoking can cause increased levels.
- Decreased test levels can result from moderate alcohol consumption, weight loss, and increased activity or endurance exercise.
- Medications that may increase test results include estrogens and progesterones.
- Medications that may decrease test results include fibrates, niacin, and statins.
- Collect serum sample
- Avoid hemolytic and lipemic specimens
- Apply pressure or a pressure dressing to the venipuncture site and assess the site for bleeding.
- Analyze fresh specimen or store at 4°C or less than 72 hours
- Specimen is stable frozen at -20°C for 6 months or indefinitely at -70°C.
Description
Reference Range
Indications & Uses
Clinical Application
CRP levels do not consistently rise with viral infections. CRP is a protein produced primarily by the liver during an acute inflammatory process and other diseases. A positive test result indicates the presence, but not the cause, of the disease. The synthesis of CRP is initiated by antigen-immune complexes, bacteria, fungi, and trauma. CRP is functionally analogous to immunoglobulin G, except that it is not antigen specific. CRP interacts with the complement system.
The CRP test is a more sensitive and rapidly responding indicator than the erythrocyte sedimentation rate (ESR).
Increased levels indicate:
Related Tests
Drug-Lab Interactions
Procedure
Storage and Handling
MESH Terms & Keywords
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