Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones. These hormones help to maintain a healthy body weight by facilitating the binding of insulin to cell receptors. When the thyroid gland becomes underactive, the body's cells may become resistant to insulin. This can lead to low testosterone levels and a decreased libido.
Hypothyroidism
When nutrients from the food we eat enter the bloodstream, the pancreas secretes insulin. Insulin binds to receptors on the body's cells. This causes cell transporters to move from the cell's interior to the cell membrane, where they are embedded. Thyroid hormones regulate the binding of insulin to cell receptors, which facilitates the uptake of nutrients. When the thyroid gland becomes underactive, insulin cannot transfer the signal from the cell receptor to the cell's interior as effectively.
Insulin Resistance and Testosterone Production
Insulin resistance can interfere with the production of the hormone LH, which controls testosterone production. When the levels of LH drop, testosterone levels drop too. Insulin resistance can also negatively affect the secretion of testosterone from the adrenal glands and testes directly. Though the exact mechanism of action is unknown, insulin resistance could interfere with testosterone production by increasing the active levels of estrogen.
Causes of Hypothyroidism
Hypothyroidism can be a hereditary condition in which the thyroid gland slowly deteriorates; however, hypothyroidism most commonly arises as a result of treating individuals for hyperthyroidism. An overactive thyroid gland can be a dangerous condition that can lead to a sudden large surge of thyroid hormone into the bloodstream and Graves' disease, an eye disease in which the eyes bulk out of the head. The most effective treatment of hyperthyroidism is to remove the thyroid gland surgically or to administer radioactive iodine to reduce the gland's activity. Both kinds of treatments normally lead to hypothyroidism.
Treatments
Hypothyroidism is not normally a life-threatening condition, but if it goes untreated, it will lead to insulin resistance, which in turn can lead to excessive weight gain and type 2 diabetes. The most common treatment of hypothyroidism is hormone replacement. Levothyroxine, known as Synthroid, Levoxyl or Levothroid, are common thyroid hormone medicines for hypothyroidism. Milder forms of hypothyroidism can be controlled with a diet low both in calories and simple carbohydrates, such as sugar and white bread, pasta and rice.
