Differential diagnosis of pituitary thyrotroph adenomas and hyperthyroidism due to RTH syndrome can be made by using the following criteria: family history (signifies RTH not TSH-oma); pituitary lesions on imaging (signify TSH-oma); and germinal thyroid hormone receptor beta mutation (signifies RTH not TSH-oma) [4]. Here, THRB is linked to thyroid hormone resistance syndrome.