The lack of sufficient secretion from the thyroid gland during early life, as mentioned previously, results in delayed development which is called cretinism. If a child develops normally and then begins to show evidences of lack of thyroid the case is called “acquired hypothyroidism.” The condition may appear as a failure of the thyroid gland to grow or as a result of failure of the pituitary gland to stimulate the thyroid by sending the pituitary secretion necessary for this purpose. The latter failure is rare.
No one sign is typical of cretinism or insufficient thyroid, but a combination is well-nigh unmistakable. The child has physical and mental torpor. The circulation of the blood is poor. In fact, all the activities of the body are under par, including the muscle tone, sweating, and the activity of the bowel. The growth, including bones and teeth, hair and brain, is stunted. The skin is thickened and coarse and fluid accumulates under the skin. The cretin is sluggish and shows little interest in what goes on around him.
The child with deficient action of the thyroid responds rapidly to treatment with thyroid extract. Almost immediately there is improvement in color and warmth of the skin. Within a few weeks there is loss of weight as the body gets rid of the extra fluid. Almost immediately, growth begins again. Because of this prompt benefit there may be a tendency to give more and more thyroid, and this will have bad results as shown in heightened excitability, nervousness and a rise in the blood pressure.
The earlier a diagnosis can be made and the sooner treatment can be begun the better. Sometimes the damage to the brain by just a few months deficiency may be so severe that it is difficult if not impossible to overcome. Such children may become irritable and unmanageable after treatment, and the doctor must determine the amount of thyroid necessary to keep the child under control.