Purpose of review: Proper thyroid hormone signaling is essential for brain development and adult brain function. Signaling can be disrupted at many levels due to altered thyroid hormone secretion, conversion or thyroid hormone receptor binding.
Recent findings: Mutated genes involved in thyroid hormone signaling in patients and animal models have increased the understanding of the (patho-)physiological consequences of altered thyroid hormone signaling. Neuroanatomical studies have provided more insight in the underlying neuroanatomical pathways.
Summary: A number of thyroid hormone signaling pathways in the hypothalamus have been proposed, which may be involved in the adaptation of the thyroid axis, not only to hypo- and hyperthyroidism, but also to inflammation, critical illness and fasting. Studies in knockout and transgenic mouse models have shown that the individual characteristics of mutations in thyroid hormone receptors can cause striking differences in the observed phenotypes.