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Thyroid Disorders in Children

In western countries the incidence of congenital hypothyroidism has gone .. well, not gone down, but has been shown to be about 1 in 4,000, but through newborn thyroid screening programs we’ve been able to find this disease much earlier, treat it and change its outcome thyroid disease, Hashimotos thyroiditis, Graves disease. All the screening programs are based on the physiological principle of negative feedback. That is to say, primary hypothyroidism where the gland fails or is absent results in fetal and neonatal TSH hypersecretion. The incidence of congenital hypothyroidism - which as we shift into some clinical entities - is about 2 to 1 female over male, and as I said, about 1 in 4,000, 4,200.

Now what causes congenital primary hypothyroidism? Well, 90% of the time you can put everything into the category of dysgenesis. That includes aplasia - lack of a gland - hypoplasia, that is small amount of the gland typically in the right location. These events tend to be sporadic.

Now here is a baby that has a different form of congenital hypothyroidism, associated with a goiter. Very unusual. I’ll tell you, you’ve all seen babies whose chins are on their chests and it’s sometime very hard to get to this part of the body to examine them, so you’ve got to really make an effort.

What does this patient have? As we switch gears. This patient is about ten-years-old, is not quite four feet tall. She’s about eight inches shorter than she should be, and she is a little puffy and swollen and has myxedema, which you probably wouldn’t know. If you saw her in the supermarket you’d probably just think she was younger and didn’t take good care of herself, but it turns out she has acquired hypothyroidism of long-standing duration.

She had chronic lymphocytic or Hashimoto thyroiditis, which is the most common cause of acquired hypothyroidism in childhood. Females get it more often than males. It frequently runs in families and you can test for this by measuring antithyroid antibodies in the blood. These antibodies are also known as anti-thyro-peroxidase, formerly known as antithyroid microsomal antibodies, and antithyroid globulin antibodies. You only need to have one positive. Two doesn’t help you any. These antibodies do not cause the disease like the antibodies of type I diabetes.

This patient has another thyroid disease, you can see it. She has exophthalmos or proptosis along with a goiter, and of course that is Graves disease and this is the most common etiology of acquired hyperthyroidism in childhood, affecting females, once again, much more than males. Often a positive family history.

Side effects, fortunately, are infrequent but you have to be careful about skin rashes, arthritis, hepatitis, and most importantly but thank goodness most rarely, agranulocytosis. In pregnancy, as I mentioned before, you want to use PTU although we are not going to have to deal with that much. As secondary options we use radioactive iodine and occasionally surgery.

Now the last subject within this section is this young lady who happens to have a thyroid nodule on the lower pole of the left side of her thyroid gland, which I think is pretty obvious. That probably didn’t pop up like that overnight. Now when thyroid nodules are likely to be benign, the following points I would suggest; first of all, if there are multiple nodules with a diffuse goiter.

Alternatively, malignancy is suggested by previous history of neck irradiation, which is much less common than it was in the 50’s. A single, firm, irregular, painless or only slightly tender nodule in an otherwise normal-feeling gland, the persistent growth of a nodule over a few months, especially if someone gave that person thyroid hormone suppression medication; and if at the time of presentation there are enlarged adjacent cervical lymph nodes. Now if you see such a patient, you … everybody gets thyroid function tests but almost always they are normal except in a rare situation of a hyperfunctioning nodule - which I’ve never seen in 20 years.

The most common form of cancer, if present, is papillary cancer and this would generally have a good prognosis except it didn’t in the children who got it as a result of radiation exposure after Chernobyl. Other forms of cancer include papillary cancer with follicular elements, a combination, and then straight follicular cancer.

Now benign lesions should be observed for spontaneous remission in patients with Hashimoto’s thyroiditis and be treated accordingly with thyroxine. And cystic lesions may actually be cured by the fine needle aspiration. It just pops them. Now the malignant or suspicious lesions require surgical therapy and postoperative ablation with radioactive iodine and then long-term follow up.