This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Plasma, frozen
0.8 mL
0.5 mL (Note: This volume does not allow for repeat testing.)
Lavender-top (EDTA) tube
Do not collect in glass. Collect in a plastic lavender-top (EDTA) tube. Centrifuge and transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze within 24 hours and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Freeze.
Temperature
Period
Room temperature
Unstable (stability provided by manufacturer or literature reference)
Frozen
90 days (stability provided by manufacturer or literature reference)
Non-EDTA plasma specimen; EDTA plasma collected in glass
Support a diagnosis of congestive heart failure (CHF)
Immunochemiluminometric assay (ICMA)
0-100 pg/mL
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 that 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%, specificity of 86%, positive predictive value of 98%, and a negative predictive value of 89%. The overall accuracy of the diagnosis with a cutoff of 75 pg/mL was 93%. 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%, specificity of 98%, positive predictive value of 92%, and a negative predictive value of 98%.6