How body temperature is affected by thyroid hormone
Researchers say they have discovered how thyroid hormone affects blood vessels to determine body temperature, potentially explaining why people who have disorders of the thyroid gland have higher sensitivity to environmental temperature.
An overactive thyroid (hyperthyroidism) can cause a person to feel too hot, while an underactive thyroid (hypothyroidism) can cause a person to feel too cold.
The researchers from the Karolinska Institutet in Sweden said that previous studies have attributed this to how thyroid hormone affects the metabolism within cells.
The thyroid produces hormones that are able to influence how much the blood vessels dilate. In turn, this affects how much heat can escape the body.
For the study, published in the Proceedings of the National Academy of Sciences, the researchers studied mice with a mutated thyroid hormone receptor (receptor-mediated hypothyroidism). This particular mutation only affects one type of hormone receptor called TRalpha 1.
According to the researchers, TRalpha 1 is only expressed in certain tissues, and the mutation makes the tissue unresponsive to thyroid hormone, particularly in the central nervous system, bone and all muscle types.
Dr. Amy Warner, researcher at the Department of Cell and Molecular Biology at the Karolinska Institutet, told Medical News Today:
"This makes it easier to study certain aspects of thyroid dysfunction, while others remain normal. It's well known that thyroid hormone drives up basal metabolic rate, by affecting how quickly cells metabolize, and hypothyroidism should therefore show the opposite."
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