Introduction
B-type natriuretic peptide (BNP) is a hormone produced mainly by the left ventricular myocardium in response to strain.
Whilst heart failure is the most obvious cause of raised BNP levels any cause of left ventricular dysfunction such as myocardial ischaemia or valvular disease may raise levels. Raised levels may also be seen due to reduced excretion in patients with chronic kidney disease. Factors which reduce BNP levels include treatment with ACE inhibitors, angiotensin-2 receptor blockers and diuretics.
Effects of BNP
Whilst heart failure is the most obvious cause of raised BNP levels any cause of left ventricular dysfunction such as myocardial ischaemia or valvular disease may raise levels. Raised levels may also be seen due to reduced excretion in patients with chronic kidney disease. Factors which reduce BNP levels include treatment with ACE inhibitors, angiotensin-2 receptor blockers and diuretics.
Effects of BNP
- vasodilator
- diuretic and natriuretic
- suppresses both sympathetic tone and the renin-angiotensin-aldosterone system
Indications
Diagnosing patients with acute dyspnoea
Prognosis in patients with chronic heart failure
Guiding treatment in patients with chronic heart failure
Screening for cardiac dysfunction
- a low concentration of BNP(< 100pg/ml) makes a diagnosis of heart failure unlikely, but raised levels should prompt further investigation to confirm the diagnosis
- NICE currently recommends BNP as a helpful test to rule out a diagnosis of heart failure
Prognosis in patients with chronic heart failure
- initial evidence suggests BNP is an extremely useful marker of prognosis
Guiding treatment in patients with chronic heart failure
- effective treatment lowers BNP levels
Screening for cardiac dysfunction
- not currently recommended for population screening
Interpretation
NICE issued updated guidelines on diagnosis and management in 2018. Previously the first-line investigation was determined by whether the patient has previously had a myocardial infarction or not this is no longer the case - all patients should have an N-terminal pro-B-type natriuretic peptide (NT‑proBNP) blood test first-line.
Interpreting the test
B-type natriuretic peptide (BNP) is a hormone produced mainly by the left ventricular myocardium in response to strain. Very high levels are associated with a poor prognosis.
Factors which alter the BNP level:
Interpreting the test
- if levels are 'high' arrange specialist assessment (including transthoracic echocardiography) within 2 weeks
- if levels are 'raised' arrange specialist assessment (including transthoracic echocardiography) echocardiogram within 6 weeks
Serum natriuretic peptides
B-type natriuretic peptide (BNP) is a hormone produced mainly by the left ventricular myocardium in response to strain. Very high levels are associated with a poor prognosis.
| BNP | NTproBNP | |
|---|---|---|
| High levels | > 400 pg/ml (116 pmol/litre) | > 2000 pg/ml (236 pmol/litre) |
| Raised levels | 100-400 pg/ml (29-116 pmol/litre) | 400-2000 pg/ml (47-236 pmol/litre) |
| Normal levels | < 100 pg/ml (29 pmol/litre) | < 400 pg/ml (47 pmol/litre) |
Factors which alter the BNP level:
| Increase BNP levels | Decrease BNP levels |
|---|---|
| Left ventricular hypertrophy Ischaemia Tachycardia Right ventricular overload Hypoxaemia (including pulmonary embolism) GFR < 60 ml/min Sepsis COPD Diabetes Age > 70 Liver cirrhosis | Obesity Diuretics ACE inhibitors Beta-blockers Angiotensin 2 receptor blockers Aldosterone antagonists |