What is it?
Hypothyroidism is a disorder in which the thyroid gland doesn’t produce enough thyroid hormone. The symptoms of hypothyroidism are often non-specific and mild, and can include things like fatigue, feeling cold, constipation, weight gain, and problems with memory and concentration.
A study in US found, that 3.7% of the population suffers from hypothyroidism. The condition is probably even more common in developing countries, as iodine deficiency, one of the causes of hypothyroidism, is more prevalent there. Hypothyroidism affects women much more often than men, and gets more common with age.
What causes it?
Globally, iodine deficiency is by far the most common cause of hypothyroidism. It is also quite commonly caused by an autoimmune disease called Hashimoto’s thyroiditis. In it, the body’s own immune system starts to destroy the thyroid gland by mistake.
What happens during it?
The thyroid gland produces thyroid hormones, and these hormones impact nearly every cell of the body. They do things like increase the metabolism of cells, regulate bone growth and the maturation of neurons, and make the body more sensitive to certain molecules like adrenalin.
Iodine is an important building block of thyroid hormones, which is why the lack of it also leads to insufficient hormone generation. If the thyroid gland is harmed like in Hashimoto’s thyroiditis, on the other hand, then the gland obviously isn’t able to function as effectively as it should.
The lack of the thyroid hormones in the body leads to the symptoms of hypothyroidism, and most of then can be attributed to the decreased cell metabolism. Weight gain, for example, occurs if the cells don’t use as much energy as the body “expects them to” and there’s some leftover energy in the body, and feeling cold occurs because the chemical reactions involved in metabolism release heat and keep us warm.
How can it be treated?
Hypothyroidism is usually treated by giving the patient hormone replacement tablets daily. The molecules in these tablets act like the precursor of thyroid hormones in the body. This hormone replacement therapy usually has to be continued throughout the life.
Sources: https://en.wikipedia.org/wiki/Hypothyroidism, https://en.wikipedia.org/wiki/Triiodothyronine, https://en.wikipedia.org/wiki/Hashimoto%27s_thyroiditis#Treatment, http://www.nhs.uk/Conditions/Thyroid-under-active/Pages/Treatment.aspx