B-Type Natriuretic Peptide

Methodology: 
Immunochemiluminometric assay (ICMA)
Performed: 
Monday - Friday
Use: 
This test is used to support a diagnosis of congestive heart failure (CHF).
Specimen Requirements: 
Important: Indicate the patient's age and gender when ordering this test. To avoid delays in turnaround time when requesting multiple tests on frozen samples, submit separate frozen specimens for each test requested.
 

Type: Plasma (frozen)

Container/Tube: Lavender-top tube (EDTA) (Do not collect specimens in glass.)


Sample Volume: 0.8 mL

Minimum Volume: 0.5 mL (Repeat testing is not possible with this specimen volume.)

Storage: Freeze specimens immediately after collection (within 24 hours). Keep specimens frozen until the test is performed.

Stability (collection to time of analysis/testing): 
  • Ambient: 14 days
  • Refrigerated: 14 days
  • Frozen: 14 days
  • Freeze/Thaw cycles: Stable (x3)
Rejection Criteria:
  • Non-EDTA plasma specimen
  • EDTA plasma collected in glass
Reference Values: 
0 - 100 pg/mL
CPT Code (s): 
83880
Notes: 

UFHPL Test #: 28025

B-type natriuretic peptide (BNP), also referred to as brain natriuretic peptide, is a member of a family of structurally similar peptide hormones that includes atrial natriuretic peptide.1 BNP is a 32-amino-acid peptide that contains a 17-amino-acid ring structure, which is formed as the result of an internal disulfide bond. BNP is predominantly secreted by the ventricles of the heart in response to increased pressure. BNP acts as a vasodilator and has diuretic and natriuretic properties. BNP suppresses both sympathetic tone and the renin-angiotensin system. These physiologic effects serve to reduce intraventricular pressure and improve the symptoms of congestive heart failure (CHF).

BNP levels increase with age and can be transiently increased by vigorous exercise.1,2 BNP levels correlate with end-diastolic pressure and tend to be increased in patients with diminished left ventricular ejection fraction.1,3 BNP levels have been shown to be useful in the diagnosis of patients with symptoms that are consistent with CHF. Maisel and coworkers4 found that a BNP cutoff of 75 pg/mL could be used to predict systolic and/or diastolic abnormalities accurately in symptomatic patients referred to echocardiology for left ventricular function studies. They found that this cutoff identified patients with abnormal function from a population of 200 patients with a sensitivity of 95.9 percent, specificity of 86 percent, positive predictive value of 98 percent, and a negative predictive value of 89 percent. The overall accuracy of the diagnosis with a cutoff of 75 pg/mL was 93 percent. These results were similar to those found by Dao and coworkers.5 They found that BNP levels could be used to accurately identify patients with CHF from a population of patients presenting at the emergency room with shortness of breath (dyspnea). They found that a BNP value > 80 pg/mL could be used to identify patients with CHF from this population with a sensitivity of 97 percent, specificity of 98 percent, positive predictive value of 92 percent, and a negative predictive value of 98 percent.

Footnotes

  1. Maisel A. B-type natriuretic peptide levels: A potential novel “white count” for congestive heart failure. J Card Fail. 2001; 7(2):183-193. PubMed 11420771
  2. McNairy M, Gardetto N, Clopton P, et al. Stability of B-type natriuretic peptide levels during exercise in patients with congestive heart failure: Implications for outpatient monitoring with B-type natriuretic peptide. Am Heart J. 2002; 143(3):406-411. PubMed 11868044
  3. Valli N, Georges A, Corcuff JB, et al. Assessment of brain natriuretic peptide in patients with suspected heart failure: Comparison with radionuclide ventriculography data. Clin Chim Acta. 2001; 306(1-2):19-26. PubMed 11282090
  4. Maisel AS, Koon J, Krishnaswamy P, et al. Utility of B-natriuretic peptide as a rapid, point-of-care test for screening patients undergoing echocardiography to determine left ventricular dysfunction. Am Heart J. 2001; 141(3):367-374. PubMed 11231433
  5. Dao Q, Krishnaswamy P, Kazanegra R, et al. Utility of B-type natriuretic peptide in the diagnosis of congestive heart failure in an urgent-care setting. J Am Coll Cardiol. 2001; 37(2):379-385.PubMed 11216950
  6. Wu AH, Packer M, Smith A et al. Analytical and clinical evaluation of the Bayer ADVIA Centaur Automated B-type natriuretic peptide assay in patients with heart failure: A multisite study. Clin Chem. 2004 May; 50(5):867-873.
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