Blood Test for Natriuretic Peptide: Normal Ranges Decoded and Role in Heart Health

What are natriuretic peptides and why measure them?

Natriuretic peptides (NPs) are a group of hormones produced by the heart and blood vessels in response to increased pressure or stretching of the heart chambers. Their primary function is to regulate water-salt balance, blood pressure, and blood volume in the body [7].

Measuring the levels of these peptides in the blood has become one of the key tools in modern cardiology. It allows physicians not only to diagnose various cardiovascular diseases, but also to assess their severity, predict risks, and monitor treatment efficacy, especially in heart failure [1, 7].

Types of natriuretic peptides: BNP, NT-proBNP, and ANP

In clinical practice, three main types of natriuretic peptides are the most significant:

• Atrial natriuretic peptide (ANP): This peptide is produced predominantly in the atria of the heart. Studies show that ANP can serve as a biomarker for predicting atrial fibrillation (AF) in patients with embolic stroke of undetermined source (ESUS). High levels of ANP were independently associated with the detection of AF [3].
• Brain natriuretic peptide (BNP): Despite its name, BNP is mainly synthesized in the ventricles of the heart in response to their stretching and increased load.
• N-terminal pro-brain natriuretic peptide (NT-proBNP): This is an inactive fragment formed simultaneously with BNP from a common precursor. NT-proBNP has a longer half-life in the body, making it a more stable and reliable marker for laboratory testing. It is recognized as a key biomarker in the diagnosis and management of heart failure [1].

Decoding results: norms and deviations

Interpretation of natriuretic peptide test results requires consideration of many factors, including the patient's age, gender, and the specifics of the laboratory equipment used. Therefore, it is crucial to rely on the reference values provided by the specific laboratory.

Elevated levels of BNP and NT-proBNP typically indicate increased stress on the heart and may be a sign of the following conditions:

• Heart failure (HF): The higher the NP level, the more severe the degree of heart failure may be. NT-proBNP is the primary marker for the diagnosis and monitoring of HF [1].
• Pulmonary hypertension (PH): Especially that which develops as a complication of heart failure with reduced ejection fraction (HFrEF). Patients with PH exhibit significantly higher levels of BNP and NT-proBNP, which can predict the presence and severity of PH [2].
• Atrial fibrillation (AF): High levels of BNP, especially in combination with a low left ventricular ejection fraction (the BNP/LVEF ratio), may be associated with AF [4].
• Thyroid disorders: For example, overt hypothyroidism shows an elevation in NT-proBNP, indicating myocardial stress caused by thyroid dysfunction [8].
• Other conditions, such as renal failure, sepsis, and pulmonary embolism, can also lead to increased NP levels.

Normal or low levels of natriuretic peptides generally allow for the exclusion of heart failure as a cause of symptoms such as shortness of breath or edema. However, the final interpretation of results should always be performed by a physician in the context of the complete clinical picture, medical history, and other diagnostic data.

Natriuretic peptides in the diagnosis of heart failure and other conditions

• Heart failure: NT-proBNP is the primary tool for the diagnosis and management of HF [1]. Measuring it helps not only to identify the disease, but also to assess its severity and the effectiveness of ongoing therapy [7].
• Pulmonary hypertension: BNP and NT-proBNP levels are significantly higher in patients with pulmonary hypertension developing against the background of heart failure with reduced ejection fraction. These markers can help determine who requires invasive diagnostics, such as right heart catheterization [2].
• Atrial fibrillation: ANP can serve as a biomarker for detecting hidden (paroxysmal) AF, especially in patients with a stroke of unclear etiology [3]. The ratio of BNP to left ventricular ejection fraction (BNP/LVEF) may also be associated with AF in hospitalized patients [4].
• Hypothyroidism: Patients with overt hypothyroidism show elevated levels of NT-proBNP, indicating increased myocardial stress caused by thyroid dysfunction [8].

Benefits of testing and future outlook

Natriuretic peptide testing offers significant clinical and economic value:

• Clinical value: NP tests play an important role in the diagnosis, risk stratification, and management of heart failure, helping physicians make informed decisions [7].
• Cost-effectiveness: The use of NP tests helps reduce hospitalizations, optimize medication use, and, consequently, lower overall healthcare expenditures [7].
• Convenience and accessibility: The development of technologies such as point-of-care testing (POCT) devices makes testing more accessible and convenient. Such devices demonstrate high accuracy and ease of use, allowing rapid results to be obtained directly in clinical settings [1].

Expanding access to these tests and improving reimbursement policies could further enhance their positive impact on healthcare systems worldwide [7].

Sources

1. Evaluation of point-of-care N-terminal pro-brain natriuretic peptide testing for heart failure management. (Cardiology research, 2025) https://pubmed.ncbi.nlm.nih.gov/41170016/
2. Natriuretic peptides as predictors for the diagnosis of pulmonary hypertension secondary to left heart disease and the evaluation of its severity. (International journal of molecular sciences, 2026) https://pubmed.ncbi.nlm.nih.gov/42737672/
3. Atrial natriuretic peptide may be a biomarker for predicting atrial fibrillation in embolic stroke of undetermined source. (Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, 2026) https://pubmed.ncbi.nlm.nih.gov/42303893/
4. Integrated biomarkers and cardiac phenotypes associated with atrial fibrillation: real-world hospital data. (Frontiers in cardiovascular medicine, 2026) https://pubmed.ncbi.nlm.nih.gov/42222112/
5. Maximizing cost savings in heart failure management: the economic value of natriuretic peptide testing. (Peptides, 2025) https://pubmed.ncbi.nlm.nih.gov/40653048/
6. Serum N-terminal pro-brain natriuretic peptide and phosphodiesterase 4D levels in adults with overt hypothyroidism: a case-control study. (Cureus, 2026) https://pubmed.ncbi.nlm.nih.gov/42732212/

This information is for reference purposes only and cannot replace consultation with a qualified medical professional. Always consult a physician for diagnosis and treatment.