This document provides methods and materials involved in assessing mammals with acute decompensated heart failure (ADHF), as well as methods and materials involved in assessing outcomes. For example, methods and materials for using the level of plasma CNP and the level of urinary CNP to determine whether or not a mammal is developing or likely to develop more severe ADHF, as well as methods and materials for using the level of plasma CNP and the level of urinary CNP to identify patients having an increased likelihood of experiencing a poor outcome are provided.