Cardiac
NT-proBNP
NT-proBNP is the inactive N-terminal fragment released alongside B-type natriuretic peptide when cardiac myocytes are stretched by raised pressure or volume in the heart chambers. At the point of care it is used to help rule out heart failure and to support rapid triage of patients presenting with breathlessness.
Why it is measured
Because circulating levels rise as cardiac filling pressures increase, a low result makes heart failure unlikely and supports fast rule-out in primary care and the emergency department. A near-patient result in minutes can speed up triage and onward referral decisions.
| Typical range | Indicative adult rule-out: in the non-acute setting a result below roughly 125 pg/mL (equivalent to 125 ng/L) makes heart failure unlikely under European Society of Cardiology guidance, whereas NICE in the UK applies a higher non-acute threshold of about 400 ng/L. In acute breathlessness a lower rule-out cut-off near 300 pg/mL is used, with age-adjusted rule-in values that increase in older patients per local protocol. Measuring ranges differ by analyser, for example roughly 60 to 9,000 pg/mL on some strip systems and up to about 30,000 pg/mL on others. Values rise with age and with reduced kidney function, and exact thresholds vary by method, so platforms are not always interchangeable. |
|---|---|
| Sample | Lithium heparin whole blood, by capillary fingerstick or venous draw, or lithium heparin plasma, with some analysers also accepting EDTA, depending on the platform. |
| Turnaround | Approximately 8 to 15 minutes from sample to result, depending on the analyser. |
Point of care devices that report it
- Roche cobas h 232 (Roche CARDIAC proBNP+ strip)
- LumiraDx Platform (NT-proBNP test)
- Radiometer AQT90 FLEX immunoassay analyser
- Response Biomedical RAMP NT-proBNP test
- Samsung LABGEO IB10 (CHF and CHF Plus tests)
Questions, answered
Does a point-of-care NT-proBNP result replace the laboratory test?
Point-of-care NT-proBNP is designed to give a rapid result near the patient to support triage and rule-out decisions, not to override laboratory medicine. Many services confirm borderline or unexpected results against their central laboratory method and define in local protocols when a confirmatory venous sample is needed. Because methods are not always interchangeable, serial monitoring should ideally stay on the same platform.
Why are age-adjusted thresholds used for NT-proBNP?
Natriuretic peptide concentrations naturally increase with age and with reduced kidney function, so a single fixed cut-off can misclassify older adults. Guideline bodies therefore publish age-stratified thresholds to improve specificity. Clinicians apply the threshold relevant to their setting, patient age and acute versus non-acute presentation, following local policy.
What is the difference between BNP and NT-proBNP?
Both originate from the same precursor pro-hormone: BNP is the biologically active hormone and NT-proBNP is the inactive N-terminal fragment cleaved from it. They are reported in different units and carry different reference cut-offs, so the two tests are not directly interchangeable. A laboratory or service should standardise on one marker and one set of thresholds to keep results comparable over time.