Eleanor Alton, age 12, of Springfield, I11., for her question:
WHAT DOES AN UNDERACTIVE THYROID DO?
The thyroid gland is an endocrine or ductless gland that is located in the neck. When one is underactive and the gland does not produce enough of the hormone thyroxine, a person slows down, his skin grows thick and coarse and he loses vigor of mind and body. He may also gain a lot of extra weight.
A person with an underactive thyroid develops a condition known as hypothyroidism. In adults this is called myxedema.
Hypothyroidism that starts in infancy results in a condition called cretinism. Children with cretinism are called cretins. Their bodies do not grow the way they should. Their minds cannot grow, either. Because of this, the mind of such a child may never develop beyond the level of a 5 year old.
When a thyroid is overactive, it produces too much thyroxine. This may be because the gland cells are overactive. Or it may be because the gland has increased in size so that too many cells are producing thyroxine.
In either case, too much of the hormone is produced for the body to handle normally and a condition known as hyperthyroidism results. Hyperthyroidism causes extreme nervousness, increases heart action and disturbs the metabolism of the body.
The normal thyroid gland takes up iodine from the blood. When the iodine combines with other chemicals in the gland, thyroxine, an important hormone, is formed. The thyroid stores thyroxine in an inactive form.
However, when the body needs thyroxine, it is released directly into the blood vessels that run through the gland. The blood stream then carries the hormone all over the body to the body cells. In the cells, thyroxine is changed into several more active hormones that regulate the rate at which the cells change oxygen and food into heat and energy.
The thyroid also produces a hormone called calcitonin. This hormone causes calcium present in the blood to become deposited in bone. Calcitonin works together with parathorome, a hormone secreted by the parathyroid glands, to control the amount of calcium in the blood.
Still another hormone produced by the thyroid is triiodothyronine, which is similar in structure and effect to thyroxine. Both triidothyronine and thyroxine are necessary for body growth and mental development.
Goiter is an enlarged thyroid gland. It may be accompanied by either hypothyroidism or hyperthyroidism. Goiters develop when there is not enough iodine supplied to the body for the thyroid to function properly.
People used to develop goiters when they lived in certain ares of the world where neither land nor water supplied iodine for the body's use. The lack of iodine in food can be remedied by eating iodized salt.
Doctors are able to treat thyroid conditions in various ways.