To explain the onset of asthenia in subjects who had undergone a total thyroidectomy, the authors mention a possible imbalance in “non-classical” thyroid hormones such as T2, whose activity is particularly intense in the mitochondria; polymorphism of the enzymes responsible for deiodination, especially deiodinase 3; and a lack of melatonin, of which the thyroid is the second source of production. Here, TG is linked to asthenia.