Laboratory: Clinical Biochemistry  (AUTOMATED)
Test Name:
NT-proBNP - (P)
Test Code: NBNP
Clinical Information:
Test Indications: 
• NT-proBNP testing is available for Hospital and Emergency Department Patients
• Testing will be performed at HSC and SBH, but can be ordered from any hospital in Manitoba, results to be available within about an hour of the HSC or SBH laboratory receiving sample
• NT-proBNP has a very high diagnostic accuracy in discriminating heart failure (HF) from other causes of dyspnea: the higher the value, the higher the likelihood that dyspnea is caused by HF.
• NT-proBNP testing can be considered for patient presenting with atraumatic dyspnea without obvious cause, where history, physical exam, CXR and POCUS are not diagnostic or not available.
• Offering of NT-proBNP in Manitoba was under review, the current implementation has been expedited to support strained resources during COVID-19. The availability of NT-proBNP will be reviewed again once the COVID-19 situation resolves.
Cautions:
• In patients with shock, NT-proBNP cannot be used to identify cause (e.g. cardiogenic vs. septic shock), but remain prognostic.
• NT-proBNP is a marker of myocardial stress, as such may be elevated among patients with severe respiratory illnesses typically in the absence of elevated filling pressures or clinical heart failure. Much like troponin, elevation of NT-proBNP is associated with an unfavorable course among patients with ARDS. 
• Patients with COVID-19 often demonstrate significant elevation of NT-proBNP. The significance of this finding is uncertain and should not necessarily trigger an evaluation or treatment for heart failure unless there is clear clinical evidence for the diagnosis.
• NT-proBNP cannot identify the underlying cause of HF and, therefore, if elevated, must always be used in conjunction with cardiac imaging.
• NT-proBNP measurements should always be used in conjunction with all other clinical information.

Recommendations: Ezekowitz JA, O'Meara E, McDonald MA, et al. 2017 Comprehensive update of the Canadian Cardiovascular Society Guidelines for the management of heart failure. Can J Cardiol. 2017;33(11):1342-1433.
See also: Clinical Practice Change NT-proBNP Testing
Patient Preparation Instructions: Multivitamins (45–125 µg biotin) or biotin-only supplements up to 1 mg per day do not interfere with this test. Samples should not be taken from patients receiving therapy with high biotin doses (i.e. >5 mg/day) until at least 8 hours after the last dose.
Collection Devices:
Specimen Required:
Plasma: 2.0 mL

Stability 6 days refrigerated, 2 years frozen
Referral:
Serum: 2.0 mL

Samples must be transferred to an aliquot tube and stored frozen if analysis will not be complete within 48 hours (#110-10-05 Serum / Plasma Separation Procedure & Transport)
Requisition:
Reference Values:
All results are flagged as abnormal (high) at ≥ 300 pg/mL
 
All Ages
< 300 pg/mL:  Heart Failure is unlikely in Acute Care setting. Values < 125 pg/mL are normal in ambulatory care.
 
Age < 50 yr
300-450 pg/mL:  Heart Failure is possible, but other diagnoses should be considered.
> 450 pg/mL:  Consider Heart Failure or other cause of myocardial stress.  Elevation may be due to severe respiratory illnesses, including pulmonary embolism. Clinical correlation required.
 
Age 50 to 75 yr
300-900 pg/mL:  Heart Failure is possible, especially if NT-proBNP is > 450 pg/mL. Other diagnoses should be considered.
> 900 pg/mL:  Consider Heart Failure or other cause of myocardial stress.  Elevation may be due to severe respiratory illnesses, including pulmonary embolism. Clinical correlation required
 
Age > 75 yr
300-1800 pg/mL:  Heart Failure is possible, especially if NT-proBNP > 900 pg/mL. Other diagnoses should be considered.
>1800 pg/mL:  Consider Heart Failure or other cause of myocardial stress.  Elevation may be due to severe respiratory illnesses, including pulmonary embolism. Clinical correlation required.
Availability:
Stat or Routine
Testing performed at HSC or SBH
See Also:
More Information: