This is a protein hormone secreted by the failing heart into the blood stream. It helps heart failure by dilating the blood vessels in the body and it helps the kidneys eliminate the salt and water that the body retains in heart failure. The level of this hormone in the blood is elevated when a person develops heart failure and decreases when the heart failure is successfully treated.
Higher levels predict a worse prognosis for the patient.
Testing the blood for the level of this hormone is helpful in determining whether a patient's symptoms are due to heart failure or not. It is an additional measure that the heart failure is responding to treatment.