C-reactive protein (CRP) in serum/plasma

Indications

• assessment of inflammation

Reference interval

• < 1.0 mg/L
• 1.0-3.0 mg/L (moderate risk for heart disease)*
• > 3 mg/L mg/L (high risk for heart disease)*
• > 10 mg/L suggestive of:
  • systemic inflammation
  • infection
  • trauma

# reference values are race & gender-dependent mean CRP 3.0 mg/L blacks vs 2.3 whites, 3.3 women vs 1.8 men

* high-sensitivity CRP in serum used for assessing cardiovascular risk; use average of 2 measurements; 2 weeks apart (see guidelines for high-sensitivity CRP testing)

Principle

The CRP pack is used in the DuPont ACA discrete clinical analyzer to quantitatively measure C-Reactive protein levels in serum. The C-Reactive Protein (CRP) method is based on a particle enhanced turbidimetric immunoassay (PETIA) adapted to the DuPont ACA analyzer. The CRP method uses a single-pack, rate technique to measure C-reactive protein. The CRP pack contains latex particles coated with the antibody to C-reactive protein (AbPR). C-reactive protein present in the sample causes aggregation of the latex particles. The rate of aggregation is directly proportional to the concentration of C-reactive protein and is measured turbidimetrically at 340 nm. The concentration is determined by means of a previously prepared lot-specific calibration curve or mathematical function.

Clinical significance

• C-Reactive protein levels are used to indicate the presence of an inflammatory process that may be caused by bacterial infection or a physiological response
• serum CRP has better specificity for inflammation than ESR
  • serum CRP rises & falls in response to inflammation faster than ESR
• increased CRP serum levels are an independent risk factor for mortality after an acute MI
  • HMG CoA reductase inhibitor (statin) therapy appears to attenuate the risk associated with increased CRP
  • CRP serum levels do not predict response to statins
• increased CRP may be independent risk factor for cardiovascular disease
• increased CRP levels (> 0.38 mg/dL) associated with risk of inducible myocardial ischemia in patients NOT receiving statin or beta blocker
• increased risk of major coronary event in subjects with CRP in top 1/3 of general population
• little predictive value beyond lipid profile, blood pressure diabetes & smoking status {traditional risk factors}
• may be link between metabolic syndrome X & elevated CRP; both predict risk of cardiovascular events, but combined no bettter than either alone
• CRP may be useful to risk-stratify women with syndrome X
• during 16 weeks after acute coronary syndrome, serum CRP associated with a greater risk of cardiovascular death & all-cause mortality

Increases

• conditions associated with marked increase in CRP (> 10 mg/dL)
  • infections
    • septic arthritis
    • bacterial meningitis
    • bacterial pneumonia
    • cellulitis
    • pyelonephritis
    • subacute bacterial endocarditis
    • pelvic inflammatory disease
    • serious opportunistic fungal or viral infections
    • erythema nodosum leprosum
  • rheumatic diseases
    • severe rheumatoid arthritis
    • Still's disease
    • acute rheumatic fever
    • vasculitis (polyarteritis nodosa, Wegener's granulomatosis)
    • severe Crohn's disease
    • polymyalgia rheumatica
  • neoplasia
    • malignant lymphoma
    • metastatic carcinoma
    • sarcoma
  • others
    • pulmonary embolism
    • thrombophlebitis
    • surgery
    • burns
    • fractures, trauma
    • fever of unknown origin
• conditions associated with moderate increase in CRP (1-10 mg/dL)
  • infections
    • acute bronchitis
    • tuberculosis
  • rheumatic diseases
    • rheumatoid arthritis
    • Crohn's disease
    • ankylosing spondylitis
    • Reiter's syndrome
    • psoriatic arthritis
    • systemic lupus erythematosis
    • Behcet syndrome
    • scleroderma
    • dermatomyositis
    • Sjogren's syndrome
    • ulcerative colitis
    • Dressler's syndrome
  • neoplasia
    • leukemia
    • myeloproliferative disorders
    • increased risk for lung squamous cell carcinoma in smokers & former smokers, but not never smokers
  • others
    • myocardial infarction
    • congestive heart failure
    • graft-vs-host disease
    • pancreatitis
    • alcoholic hepatitis
    • sarcoid
    • idiopathic pulmonary fibrosis
• conditions associated with insignificant increase in CRP (< 1 mg/dL)
  • infections
    • aseptic meningitis
    • otitis media
    • cystitis
    • viral hepatitis
    • uncomplicated viral or fungal infection
  • rheumatic diseases
    • osteoarthritis
    • chondrocalcinosis
    • pauciarticular juvenile rheumatoid arthritis
  • neoplasia
    • basal cell carcinoma
  • others
    • angina
    • stroke
    • gastritis, peptic ulcer disease
    • alcohol withdrawal
    • COPD, asthma
    • hypertension
• serum levels also increase with:
  • obesity
  • diabetes
  • metabolic syndrome
  • estrogen

Specimen

Patient preparation: No special patient preparation is required. Collect blood samples by venipuncture following established good laboratory practices. If the sample is obtained through the infusion set, flush the line thoroughly with saline before taking the blood sample.

More general terms

• general chemistry test

More specific terms

• C-reactive protein (CRP) in serum/plasma high-sensitivity

Additional terms

• C-reactive protein; contains: C-reactive protein(1-205) (CRP PTX1)
• NycoCard[Tm] CRP Whole Blood

Component of

• endocrinology 7 analyte panel
• inflammatory markers (iAGE)
• connective tissue disease panel; collagen disease panel; SLE panel
• arthritis panel

Patient information

C-reactive protein (CRP) in serum patient information