The measurement of NT-proBNP natriuretic peptide is used as an adjunctive test in the diagnosis of congestive heart failure.
Natriuretic peptides are structurally similar peptides produced by whole-body cells. Two of them, A-type natriuretic peptide (also known as vaginal natriuretic peptide or ANP - Atrial Natriuretic Peptide) and B-type natriuretic peptide (also known as cerebral natriuretic peptide or BNP - Brain Natriuretic Peptide) myocardial. ANP is produced exclusively by the muscle cells of the heart, while BNP is produced by the muscle cells of both the vagina and the heart. The ANP and BNP natriuretic peptides are involved in maintaining homeostasis by promoting diuretic and sodium elimination (natriuretic). BNP is released from the ventricles, especially the left ventricle, during increased pressure or its massive overload. It causes dilation of the arteries and veins and also reduces the levels of vasoconstrictor hormones and sodium retention neurons. It is now known that abdominal overload leads to the release of both BNP and N-terminal (amino-terminal) proBNP (NT-proBNP).
Although ANP was the first natriuretic peptide, what is widely used clinically is BNP. This is partly due to its longer half-life (20 minutes BNP vs. 3 minutes ANP) and also to the fact that BNP levels are unaffected by exercise, while ANP levels may be affected by normal physical activity. NT-proBNP has a half-life of 120 minutes, making it somewhat less useful for tracking abrupt changes. However, it is used in the diagnosis of heart failure, and several studies suggest that it is a powerful predictor of mortality.
The use of BNP in assisting in the diagnosis of heart failure is well documented. BNP levels are elevated in patients with symptomatic heart failure in a non-depressive state. However, patients with left ventricular dysfunction compensated by medical treatment may have normal BNP levels. BNP measurement is particularly useful in distinguishing between dyspnoea due to heart failure and other causes of dyspnoea. BNP levels may increase in women and the elderly while obesity may show (falsely) a reduction.
Possible Interpretations of Pathological Values
- Increase: Acute lung injury, acute myocardial infarction, chronic renal failure, cirrhosis, congestive heart failure, coronary angioplasty, hypertension, hyperkalaemia, left ventricular hypertrophy, pneumonia.
- Decrease: Therapeutic response to antihypertensive therapy, therapeutic response to diuretic therapy.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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