The assay of the B-type natriuretic peptide (BNP) consists of a laboratory test that measures the concentration in the blood of the BNP and / or the aminoterminal inactive fragment of the B-type natriuretic pro-peptide (NT-proBNP or simply NT-BNP) .
BNP is a peptide, ie an organic compound, resulting from the union of 32 amino acids. It is produced in the heart not directly as such but joined to the inactive N-terminal fragment, composed of 76 amino acids.
The test is particularly useful to detect the risk of heart failure or heart failure and, in particular, to evaluate any changes in one of the four cavities of the heart, the left ventricle, and their severity.
In fact, BNP is mainly produced by the left ventricle. When it dilates due to excessive workload, caused for example by pressure changes, the concentration of BNP and NT-proBNP in the blood increases significantly. This can be a sign not only of heart failure, but also of other abnormal situations that involve the heart and the circulatory system. Once released into the blood, BNP plays a role similar to that of a hormone, in other words it determines functional responses in cells and tissues located at various distances from the site where it was secreted. BNP carries out a diuretic, natriuretic and vasodilator activity, increasing the elimination of sodium and water through the kidneys and dilating the width of the blood vessels. In doing so, BNP lowers arterial and venous pressure and increases the heart's ability to pump blood into the arteries.
The doctor may request a BNP test if there are signs and symptoms (symptoms) related to heart failure such as shortness of breath and difficulty, fatigue, swelling of the ankles, feet, legs and abdomen. Furthermore, the examination may also be requested by the emergency room in the event that heart failure must be quickly ascertained.
Even after taking treatment, testing can be helpful in assessing its effects. Since heart failure is sometimes associated or confused with other diseases, such as lung diseases, the measurement of BNP and NT -proBNP can help the physician to make an accurate diagnosis and to prescribe targeted treatment for the specific disease.The test
The "test (test) measures the concentration of BNP and / or NT-proBNP in the blood. It is performed by taking a small amount of blood (sample) from a vein in the arm and does not require any special preparation.Results
In addition to physiologically increasing with aging, BNP values rise significantly in people with left ventricular hypertrophy and heart failure. BNP can also increase in diseases involving increased atrial and ventricular pressure such as, for example, renal failure, cirrhosis of the liver with ascites and in the presence of unstable angina and pulmonary hypertension.
When the test result is normal, ie the BNP value is less than 100 pg / ml (picograms per milliliter or 10-12 grams per milliliter) and the "NT-proBNP is less than 300 pg / ml, it is It is possible to exclude with a high degree of probability the presence of dysfunction of the left ventricle (low risk of false negatives).
The level of BNP in the blood increases with the worsening of the disorders (symptoms) caused by heart failure, while it decreases when the condition is stable. In people who have stable heart failure, however, the value of BNP is higher than that present in healthy people. BNP values also indicate the severity of heart failure. The test can be used to ascertain (diagnose) a heart attack and to track (monitor) response to treatment over time.
Therefore, elevated levels of BNP / NTproBNP in the blood may indicate the presence of severe heart disease, while more modestly increased values may indicate milder forms.
It is important to highlight that if the BNP levels are just above the normal limit, this does not mean that you are in the presence of a disease (fair risk of false positives).
For this reason, the results of the examination must always be evaluated by the attending physician in relation to the general state of health of each person. The relationship and dialogue with your doctor is essential in order to ask for information and clarifications, to express doubts and concerns and to know the meaning of your test result.