Diagnostic Use
BNP is a 32 amino acid hormone secreted from cardiac myocytes subjected to increased ventricular wall stress.
NT-proBNP is the inactive cleavage product of the secretion of BNP and is used as a marker of BNP. Its half-life is approximately 40 minutes, compared with a half-life of approximately 20 minutes for active BNP. Our lab measures NT-proBNP.
Causes of elevated BNP or NT-proBNP
Cardiac:
Congestive Heart Failure
Acute Coronary Syndromes
Left Ventricular Hypertrophy
Hypertrophic & Restrictive Cardiomyopathy
Constrictive Pericarditis
Valvular Heart Disease
Atrial Fibrillation
Supraventricular Tachycardia
Non Cardiac:
Chronic Obstructive Pilmonary Disease
Pulmonary Embolism & Pulmonary Hypertension
Sepsis
Hypertension
Subarachnoid Haemorrhage
Renal Failure
Levels in health and disease can be affected by:
Age — increasing with increasing age
Gender — slightly higher in females
Obesity — levels are lower with increasing BMI.
Race — levels are higher in Caucasians compared with African Americans
Reference Intervals
Ruling out heart failure:
A level <35 pmol/L strongly rules out heart failure (any age).
Ruling in heart failure:
The level which strongly supports heart failure depends on age:
| <50 years |
>53 pmol/L |
| 50 – 75 years |
>106 pmol/L |
| >75 years |
>212 pmol/L |
Note that some clinical guidelines use alternate units . To convert between different units, use the following formulae:
| To change from pg/mL to pmol/L |
Multiply by 0.118 |
| To change from ng/L to pmol/L |
Multiply by 0.118 |
| To change from pmol/L to pg/mL |
Multiply by 8.457 |
| To change from pmol/L to ng/L |
Multiply by 8.457 |