Is there a need to redefine the upper normal limit of TSH? This is the title of a new paper of Brabant, G. et al. European Journal of Endocrinology (2006) 154, Issue 5, 633-637. In this paper the authors states that the available evidence for lowered upper TSH cut-off values and their potential therapeutic implications ^"there is presently insufficient justification to lower the upper normal limit of TSH and, for practical purposes, it is still recommended to maintain the TSH reference interval of 0.4–4.0 mU/l."