see: [[Congestive Heart Failure|Heart Failure]], [[Pulmonary Hypertension]] **These now play a pivotal role in the diagnosis and treatment of heart failure.**  They add **critical supportive** evidence in conjunction with echocardiography and may be used to **exclude** heart failure.  The plasma concentration of natriuretic peptides (NPs) can be used as an initial diagnostic test, especially in the non-acute setting when **echocardiography is not immediately available.**  Elevated NPs help establish:  - An initial working diagnosis - Identify those who require further cardiac investigation - Patients with values below the cut-point for the exclusion of important cardiac dysfunction do not require echocardiography. > Patients with **normal** plasma NP concentrations are unlikely to have HF. The upper limit of “normal” in the **non-acute** setting for:  - B-type natriuretic peptide (BNP) is **35 pg/mL**  - N-terminal pro-BNP (NT-proBNP) it is **125 pg/mL** In the **acute** setting, higher values should be used:  - BNP: 100 pg/mL - NT-proBNP:  300 pg/mL ## With respect to “ruling out” heart failure, current Australian guidelines say:  - BNP < 100 ng/L - NT proBNP < 300 ng/L   ## With respect to “ruling in” heart failure, current Australian guidelines say: - BNP > 400 ng/L - NT proBNP: - 450 ng/L (for age < 50 years).  - 900 ng/L (for age 50-75 years). - 1800 ng/L (for age > 75 years). > [!quote] > "Weirdly, the use of BNP to discriminate between different causes of pulmonary oedema has attracted some strongly pejorative comments from the LITFL audience. Its use in the context of emergency medicine was somehow viewed as wasteful and lazy, a crutch of the amateur. The real man examines the patient and takes a full history, they might say. However, BNP has been well validated in that setting ([Maisel et al, 2002](https://www.nejm.org/doi/full/10.1056/NEJMoa020233)) and appears to be more accurate than any historical information, physical examination findings or other laboratory investigations.   [Karmapaliotis et al (2007)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2278171/) also investigated this issue in the ICU setting, where one may not have the luxury of good history or examination.  At a cut-off twice as high as in the ED (≤ 200 pg/ml), BNP had a specificity of 91% for ARDS. However, it must be pointed out that these studies excluded patients with known severe systolic dysfunction. BNP is also raised in renal failure and sepsis (like troponin), and has the additional limitation of rarity and expense. The downtown hospitals of rural Nebrahoma may not have BNP kits available to every breathless patient." > \-[Deranged physiology chapter on pulm oedema](https://derangedphysiology.com/main/required-reading/cardiovascular-intensive-care/Chapter-230/pulmonary-oedema)