NT-ProBNP – a new laboratory parameter for evaluating heart failure

NT-proBNP (N-terminal pro brain natriuretic peptide) is a relatively new biochemical marker that facilitates and supplements diagnostics, especially for the early stages of heart failure and patient care.
As an endocrine substance of the heart, the prohormone (brain natriuretic peptide) is released as a response to increased mechanical wall strain. The active hormone BNP is split off from the prohormone. This is an antagonist of the renin-angiotensin-aldosterone system and regulates the electrolyte and fluid balance in the body. It causes a reduction in the circulating volume by increasing glomerular filtration and preventing the reabsorption of sodium in the tubules. There are BNP receptors in the kidneys, brain and blood vessels.
With the physiologically active but unstable BNP, NT-proBNP occurs in a ratio of 1:1. NT-proBNP is stable for 72 hours and independent of the sampling conditions (time of day, body position).
The activation of proBNP in the left ventricular myocardium is quick and correlated to the degree of severity of heart failure or inversely to the left ventricular pump function. An early diagnosis and therefore early therapy are important, since untreated heart failure has a poor prognosis.

Area of application
The possible areas of application for NT-proBNP are:

  • Ruling out or diagnosing heart failure where the leading symptom is dyspnoea and the underlying disease is unknown.
  • Early identification of patients with left ventricular dysfunction (systolic and diastolic)
  • Estimating the prognosis of patients with heart failure
  • Monitoring therapy in patients with heart failure (monitoring therapeutic success)

Test material
1 ml of serum or 1 ml of lithium heparin plasma

Reference range

Decision points for patients:
 < 75 years ≥ 75 years Dimension
Healthy subjects 110 589 pg/ml
Median: (28.5) (172) pg/ml
Cut off: 125 450 pg/m

Assessment
A result in the standard range – with the leading symptom of „dyspnoea” – almost completely rules out heart failure (negative predicative value ≥ 97 %).
Pathological values – particularly low elevated values – can be caused by underlying reasons other than heart failure (age, renal failure gender (women), etc.).


Literature

Thomas, 7th edition; Leitlinien zur Therapie der chronischen Herzinsuffizienz; second, revised version.

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