BNP

Test Code
NT-proBNP(BHS)


Alias/See Also
BNP


Preferred Specimen
(LT GREEN) PLASMA


Minimum Volume
1mL


Other Acceptable Specimens
EDTA PLASMA


Instructions
Remove serum or plasma from the clot, red blood cells, or separator gel if testing will be delayed more than 24 hours.


Specimen Stability
Specimen Type Temperature Maximum Storage Time Special Instructions
Serum/Plasma Room temperature
(20 to 25°C)
48 hours Remove serum or plasma from the clot, red blood cells, or separator gel if testing will be delayed more than 24 hours.
  2 to 8°C 3 days Remove serum or plasma from the clot, red blood cells, or separator gel if testing will be delayed more than 24 hours.
  -20°C or colder 30 days Remove serum or plasma from the clot, red blood cells, or separator gel.


Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Grossly Hemolyzed


Methodology
Chemiluminescent microparticle immunoassay (CMIA)

Setup Schedule
Daily


Report Available
1 day


Limitations
·Elevated NT-proBNP concentrations may be associated with impaired renal function (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m2), history of HF and other conditions such as acute coronary syndrome, atrial fibrillation, pulmonary embolism, valvular heart disease, myocarditis, pulmonary hypertension, stroke, and sepsis, which may lead to false positive results. Obesity (body mass index [BMI] ≥ 30 kg/m2)3 and other conditions such as flash pulmonary edema, pericarditis, and cardiac tamponade may lower NT-proBNP concentrations, which may lead to false negative results.
·Results should be used in conjunction with other data; e.g., symptoms, results of other tests, and clinical impressions.
·If the NT-proBNP results are inconsistent with clinical evidence, additional testing is recommended.
·The Alere NT-proBNP for Alinity i assay is susceptible to interference effects from total protein > 12.6 g/dL. Total protein at 15.2 g/dL decreased NT-proBNP values at 125 pg/mL by -12.7%.
·Specimens from patients who have received preparations of mouse monoclonal antibodies for diagnosis or therapy may contain human anti-mouse antibodies (HAMA). Such specimens may show either falsely elevated or depressed values when tested with assay kits such as Alere NT-proBNP for Alinity i that employ mouse monoclonal antibodies. Additional information may be required for diagnosis.13, 14
·Heterophilic antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this interference, and anomalous values may be observed. Additional information may be required for diagnosis.15
·Rheumatoid factor (RF) in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays.15


Reference Range
  Age Range                  Sex         (pg/mL)
18 to < 50 years old     Female  < 15.8 to 104.8 
                                     Male      < 15.8 to 180.3
50 to 75 years old        Female  < 15.8 to 334.1
                                     Male      < 15.8 to 451.6
> 75 years old              Female  < 15.8 to 956.1
                                     Male      < 15.8 to 683.0

Clinical guidelines recommend using natriuretic peptides in
emergency department (ED) for diagnosis or exclusion of HF.
The performance of the Alere NT-proBNP for Alinity i assay
was evaluated in an ED setting using published age-independent
rule-out and age-dependent rule-in cutoffs. Emergency
Department- For patients presenting to the ED with clinical
suspicion of HF, the results should be interpreted as 
indicated in the following table.

NEGATIVE: HF unlikely
(All ages) < 300.0 pg/mL

GRAY ZONE: INDETERMINATE
(CONSIDER OTHER CAUSES OF NT-proBNP ELEVATION)
(Ages 18 to < 50) >/= 300.0 to < 450.0 pg/mL
(Ages 50 to 75)   >/= 300.0 to < 900.0 pg/mL
(Ages > 75)       >/= 300.0 to < 1800.0 pg/mL

POSITIVE:HF LIKELY
(Ages 18 to < 50) >/= 450.0 pg/mL
(Ages 50 to 75)   >/= 900.0 pg/mL
(Ages > 75)       >/= 1800.0 pg/mL

*NT-proBNP increases with impaired renal function.
*NT-proBNP decreases with obesity (BMI >/= 30 kg/m^2).


Clinical Significance
Heart failure (HF) is a complex clinical syndrome that can result from structural or functional cardiac disorders causing impairment of ventricular filling or ejection of blood from the heart.1, 2 HF is a clinical diagnosis based upon patient history and physical examination in conjunction with laboratory tests and imaging procedures.2, 3 Symptoms of HF include dyspnea, ankle swelling, fatigue, and weakness which may be more pronounced with exertion.4
The American Heart Association (AHA) / American College of Cardiology (ACC) stages of HF3 highlight the development and progression of the disease from stage A (at risk of HF, asymptomatic) to stage B (pre-HF, asymptomatic), stage C (symptomatic HF), and stage D (advanced HF). The stages are defined by clinical signs and symptoms, presence of risk factors, and comorbid conditions. Progression from stage A through stage D is associated with increasing levels of cardiac biomarkers (including natriuretic peptides) and echocardiographic findings of structural heart disease and ventricular dysfunction, along with worsening symptoms of HF that interfere with daily life, increased rate of hospitalization, and elevated risk of mortality. For stage C and D HF, the New York Heart Association (NYHA) classification is utilized to categorize patients based on symptoms and functional capacity.3
B-type natriuretic peptide (BNP) is a natriuretic hormone synthesized and secreted into the blood stream by cardiac myocytes in response to volume overload, increased stress on ventricular walls, and ventricular hypertrophy.5 Physiologically active BNP and biologically inert 76 amino acid peptide NT-proBNP are formed through the proteolytic cleavage of the precursor proBNP.6 In patients presenting with dyspnea, the measurement of NT-proBNP is useful to support diagnosis or exclusion of HF.3
In patients with impaired renal function, decreased glomerular filtration rate (GFR) is associated with increased NT-proBNP concentration, since NT-proBNP is cleared by the kidney. BNP/NT-proBNP levels may also be modified due to biological factors like age, sex, and body mass index.5 Age has the strongest effect, leading to the use of age-dependent positive cutoffs.2, 7 Elevated natriuretic peptide (BNP/NT-proBNP) levels should be interpreted in the context of other clinical information; they should not be used in isolation to diagnose HF.


Performing Laboratory
West Roxbury Chemistry
Jonathan Dryjowicz-Burek
857-203-5418


Last Updated: June 25, 2025


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