The normative term for b-type urinary natriuretic peptide is B-type natriuretic peptide (BNP), and the normal range for BNP in the elderly is <35ng/ml. According to the guidelines, acute heart failure can usually be excluded with BNP<100ng/ml and chronic heart failure can usually be excluded with BNP<35ng/ml. The diagnostic sensitivity and specificity of BNP is not as good as that of N-terminal B-type natriuretic peptide (NT-proBNP), and the diagnostic range set by NT-proBNP varies depending on the age of the patient: Acute heart failure can be diagnosed with NT-proBNP greater than 450 ng/L in patients younger than fifty years of age, 900 ng/L in patients between the ages of fifty and seventy-five years of age, and 1,800 ng/L in those older than seventy-five years of age. When B-type natriuretic peptide is elevated or discomfort such as shortness of breath, fatigue, or bilateral lower extremity edema occurs, one should seek medical attention promptly to avoid delaying the condition.