Figure 3: Bland-Altman plot showing method comparison using patient specimens (n=40). The upper reference limit for normetanephrine and metanephrine is 1.1 and 0.3 nmol/L, respectively, and is represented as a vertical line on each graph. The mean difference is shown with a horizontal line and was 3.5% for normetanephrine and -1.6% for metanephrine.