Constitutively activating mutations of the TSHR are the major cause for nonautoimmune
hyperthyroidism, which is based on ligand independent, permanent receptor activation.
Several reports have highlighted the difficulties to determine whether a TSHR mutation is
constitutively active or not especially for borderline cases with only a slight increase of the
basal cAMP activity. Current methods to precisely classify such mutants as constitutively
active or not, are limited. In some cases, in vitro characterization of TSHR mutants has led to …