NT-proBNP

Order Code

---

5722

Preferred Specimen

---

Volume: 2 mL serum

Collection Method: Use a serum separator tube (SST). Allow the tube to stand upright for a minimum of 30 minutes to ensure proper clotting. Subsequently, centrifuge the sample within 2 hours of collection.

Storage: Refrigerate the serum after separation.

ContainerType

---

Serum separator tube

Alternate Specimen Requirements

---

Volume: 2 mL serum

Collection Method: Utilize a plain red-top tube. Allow the sample to clot upright for at least 60 minutes. Afterward, centrifuge the sample and transfer the serum to a plastic transport tube within 2 hours of collection. Clearly label the tube as containing serum from a plain red-top tube.

Storage: Refrigerate the serum after separation.

Minimum Volume

---

Adult: 0.5 mL serum
Pediatric: 0.2 mL serum (does not allow for repeat or
additional testing).

Transport Temperature

---

Refrigerated

Expected Turnaround Time

---

1-3 days

Specimen Stability

---

3 days room temperature; 6 days refrigerated; 1 month frozen

Methodology

---

Electrochemiluminescence Immunoassay (ECLIA)

Rejection Criteria

---

• Gross hemolysis
  

Overview

---

Natriuretic peptides, including N-terminal pro B-type natriuretic peptide (NT-proBNP) and B-type natriuretic peptide (BNP), are neurohormones initially discovered in the brain but are predominantly released from the heart. Both are produced in the cardiac ventricles from the precursor pro-B-type natriuretic peptide (proBNP) in response to increased circulatory volume and stretching of the ventricular walls. ProBNP is cleaved into two fragments: the biologically active BNP and the degradation product NT-proBNP. Both peptides are essential in diagnosing heart failure (HF), and though they are often considered equivalent in clinical practice, their levels are not directly interchangeable. Nonetheless, their response patterns are similar enough that results can generally be viewed as comparable (Maisel, 2008). NT-proBNP is gaining favor over BNP, primarily due to its superior analytical stability and simpler sample handling.

When integrated with other clinical data, NT-proBNP can help exclude, and to a lesser extent confirm, the diagnosis of HF. However, no single NT-proBNP threshold definitively distinguishes the presence or absence of HF. In clinical contexts, higher NT-proBNP levels are correlated with worsening HF severity, left ventricular dysfunction, and poorer prognosis (Januzzi, 2006; Maisel, 2008).

Clinical Significance

---

• Increased levels support a diagnosis of congestive heart failure (CHF)
• Evaluation of acute dyspnea in both outpatient and inpatient settings where a low value excludes heart failure
• Assists in differentiation between heart failure and a pulmonary cause (COPD, pneumonia, pulmonary embolism) of dyspnea
• Monitor results of treatment for heart failure
• Risk stratification of patients with acute coronary syndrome and heart failure

Additional Information

---

The role of serial BNP measurements in guiding HF treatment remains uncertain. A recommended approach is to measure BNP levels upon admission, 24 hours after treatment begins, and at discharge. Measuring BNP levels during acute clinical deterioration is also valuable. A decrease in BNP/NT-proBNP levels at discharge is typically associated with favorable outcomes.

In healthy individuals, BNP and NT-proBNP concentrations are around 10 pg/mL. However, in response to volume overload and ventricular stretch, these levels rise at different rates and persist for varying durations. BNP has a short half-life (about 20 minutes) and is cleared by various mechanisms, whereas NT-proBNP has a longer half-life (60–120 minutes) and is exclusively cleared via the kidneys. As a result, NT-proBNP levels are approximately 4 to 10 times higher than BNP and remain elevated for a longer period. Because NT-proBNP is more stable and less impacted by hemodynamic fluctuations, it is considered a better reflection of the average left ventricular filling pressures over the previous 12 hours.

Interpretative Information

---

Interpreting NT-proBNP levels requires considering the patient’s clinical history and physical examination, as well as factors that might influence laboratory results, such as age, gender, body composition, and renal function. Either BNP or NT-proBNP can effectively rule out HF as the cause of dyspnea in acute settings. Symptomatic patients with BNP or NT-proBNP within the normal reference range are unlikely to have HF, while an elevated initial level may suggest a potential risk, prompting further cardiac evaluation.

In appropriate clinical situations, elevated NT-proBNP levels suggest the presence of heart failure, with higher levels indicating more significant volume overload. In cases where NT-proBNP levels fall into the intermediate range, other clinical factors—such as left ventricular dysfunction, renal impairment, or right ventricular dysfunction due to cor pulmonale or acute pulmonary embolism—must be assessed to evaluate the likelihood of HF.

If heart failure is still suspected despite normal NT-proBNP levels, conditions like obesity, flash pulmonary edema (symptoms occurring within 1 hour), or valvular heart disease (e.g., acute mitral regurgitation) should be considered. Conversely, if heart failure is unlikely despite elevated NT-proBNP levels, non-cardiac causes like acute pulmonary embolism (with right ventricular strain), chronic lung conditions (e.g., cor pulmonale), myocardial ischemia, or renal failure should be explored.

Limitations

---

• Results vary by laboratory and methodology. Values obtained with different assay methods should not be used interchangeably in serial testing. It is recommended that only one assay method be used consistently to monitor each patient’s course of therapy.
• Variations of up to 25% may represent biologic variation unrelated to heart failure.
• Not all patients with symptomatic HF have high BNP/NT-proBNP concentrations and not all asymptomatic patients have low values.

References

---

Diagnostic Role

---

The American College of Cardiology endorses measuring BNP and NT-proBNP levels in the evaluation of dyspnea when the contribution from HF is unclear. Final diagnosis requires interpreting levels in the context of all available clinical data and should not be considered a stand-alone test.

Alias

---

• N-terminal probnp
• nt probnp
• probnp
• probrain natriuretic peptide

Test Setup Days

---

Monday through Friday PM shift

CPT

---

83880 LOINC: 33762-6

Reference Range

---

IF NT-ProBNP is less than 300 PG/ML, heart failiure is
unlikely for all ages.
Age . . . . . Heart Failure Likely
<50 YEARS: >=450 PG/ML
50-75 YEARS: >=900 PG/ML
>75 YEARS: >=1800 PG/ML

UNIT CODE	UNIT CODE NAME	ANALYTE	GENDER	AGE	REFERENCE RANGE	Units of Measure
5722	PROBNP	PROBNP	NOT SPECIFIED	0Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	NOT SPECIFIED	49Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	NOT SPECIFIED	75Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	NOT SPECIFIED	150Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	MALE	0Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	MALE	49Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	MALE	75Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	MALE	150Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	FEMALE	0Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	FEMALE	49Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	FEMALE	75Y	SEE BELOW	PG/ML
5722	PROBNP	PROBNP	FEMALE	150Y	SEE BELOW	PG/ML