A patient is seen in the emergency department (ED) with heart failure secondary to dilated cardiomyopathy. What key diagnostic test does the nurse assess to determine the severity of the patient's heart failure?
a) Complete blood count (CBC)
b) B-type natriuretic peptide (BNP)
c) Serum electrolytes
d) Blood urea nitrogen (BUN)
Answer: B-type natriuretic peptide (BNP)