BNP

Purpose:
Natriuretic peptide testing – B-type natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NT-proBNP) is an important tool for rapidly assessing adults presenting with new suspected acute heart failure.

NICE Clinical guideline [CG187], 2021: Acute heart failure: diagnosis and management
1.2.2 In people presenting with new suspected acute heart failure, use a single measurement of serum natriuretic peptides BNP or NT-proBNP) and the following thresholds to rule out the diagnosis of heart failure:

BNP less than 100 ng/litre
NT-proBNP less than 300 ng/litre.

1.2.3 In people presenting with new suspected acute heart failure with raised natriuretic peptide levels (see recommendation 1.2.2), perform transthoracic Doppler 2D echocardiography to establish the presence or absence of cardiac abnormalities.

NICE guideline [NG106], 2018 Chronic heart failure in adults: diagnosis and management also recommend the measurement of (NT-proBNP) in people with suspected chronic heart failure as part of the diagnostic pathway.

NT-proBNP conc.	Recommendation
< 400 ng/L	Heart failure not confirmed consider other causes of symptoms
400 – 2000ng/L	Refer for special clinical assessment including ECHO within 6 weeks
> 2000 ng/L	Urgent refer for special clinical assessment including ECHO within 2 weeks

Consider measuring NT-proBNP as part of a treatment optimisation protocol only in a specialist care setting for people aged under 75 who have heart failure with reduced ejection fraction and an eGFR above 60ml/min/1.73m2.

Scope:
Participants can enrol in the programme most appropriate to their testing method and analyte i.e. laboratory methods for BNP, NT-proBNP or point of care testing (PoCT). Separate samples are provided for BNP and NT-proBNP. PoCT devices are assessed separately to laboratory methods. Three samples covering the appropriate physiological and pathological range including challenging samples near the diagnostic thresholds are distributed bimonthly.

The base material for BNP is human EDTA plasma and for NT-proBNP lithium heparin plasma to reflect the preferred sample type used for patient testing. The samples consist of a panel of linearly related samples produced from donations from healthy volunteers spiked with natriuretic peptides. Recombinant human BNP-32 and NT-proBNP respectively are added, with the addition of protease inhibitors to improve stability. For BNP the samples are dispatched by Courier on dry ice, however, multiple distributions can be dispatched in one shipment to minimise costs.

Surrogate, clinically appropriate linear panels suitable for both Laboratory and PoCT analysers are provided. The programmes assess both laboratory and method performance, including bias, within and between batch imprecision and linearity.