This is a correction of Biochem Med (Zagreb) 2021;31(1):010706, DOI: https://doi.org/10.11613/BM.2021.010706 .
Since the publication of the article, the authors have noticed some errors: on page 5, right column, under the heading Case 3, the concentrations of normetanephrine should be in µmol/24h instead of mmol/24h; and on page 6, left column, under the heading of Case 6, the concentrations of metaphrine should be in µmol/24h instead of mmol/24h. We apologize to the authors for any inconvenience caused to the readers.