Hyperthyroidism and type 1 diabetes


I have previously explained the most common hormone deficiency in persons with type 1 diabetes: hypothyroidism (low thyroid) due to a common autoimmune disorder known as Hashimoto's thyroiditis (model gland shown on the right). I will next explain the opposite state created by an overactive thyroid and also driven by a misdirected immune system. This condition is called Graves' disease (a specific type of hyperthyroidism, the gland shown on the left; the middle is an example of a normal size thyroid wrapped around the windpipe).

The first president Bush (George H. W. Bush) was found to have this condition after he was initially discovered to have the heart condition atrial fibrillation in May, 1991. Looking back, he had also experienced weight loss and fatigue, plus a noticeable change in his hand writing most likely due to the tremor that goes along with hyperthyroidism. There are many major and minor symptoms of overactive thyroid which often get dismissed as something else until the evidence is almost undeniable. In short, too much thyroid hormone accelerates your metabolism and other bodily functions whereas too little thyroid tends to slow them down.

Graves' disease (hyperthyroidism) is suspected when symptoms of a persistent rapid pulse, hand tremors, weight loss, inability to stay focused on tasks, feeling hot, frequent trips to the bathroom, and irritability or deterioration in school or work performance is noticed. None of these symptoms by themselves are very specific for anything, but taken together and perhaps with the presence of an enlarged thyroid gland (goiter) point to an overactive thyroid as the culprit.

It's pretty easy to diagnose hyperthyroidism. All it takes is a blood test. But since there are several causes of hyperthyroidism (Graves disease being only one of them), further testing is needed to arrive at a proper diagnosis. An endocrinologist is best suited to evaluate and diagnose a person with an overactive thyroid condition.

There are three general treatment options for the most common form of overactive thyroid in young people, Graves' disease. The first consists of oral medications to block the production and release of the hormone from the renegade gland. These medications must be taken several times daily, for years. Second, the oldest therapy for an overactive thyroid is to surgically remove the gland, a procedure called thyroidectomy. It's important to know your thyroid surgeon's experience with performing this procedure. It's best that the surgeon does at least 30 operations of this type each year (or more) to be considered "high volume". Third, for decades it has been known that a modest dose of radioactive iodine, taken by mouth, can concentrate inside the thyroid gland (only) to a sufficient degree to destroy the gland slowly over time. This is called a radioiodine ablation. President Bush underwent an ablation while in office in 1991 with no significant ill effects.

Each Graves treatment option carries certain risks plus none are 100% guaranteed to work. Side effects of the anti thyroid pills can affect the liver, joints, lungs, skin and bone marrow. Removal of a thyroid even by an experienced surgeon can remove other important organs (parathyroid glands) or damage the nerve that operates the right side of the vocal cords. Radio iodine therapy may not work the first time and might require a repeat treatment. Plus as the gland starts to breakdown in the weeks after an ablation, it releases large amounts of premade thyroid hormone in large enough amounts to spill into the blood stream uncontrollably and cause worse hyperthyroid symptoms, at least temporarily. In spite of the obvious concerns of ingesting radiation, the amount is small and long term follow up studies have proven ablation to be a safe therapy. An ablation is performed by a Nuclear Medicine specialist. Avoiding surgery, scars and a hospitalization are reasons many choose ablation as a long term solution for definitively treating Graves' disease. Most persons, especially young people, choose not to stay on oral anti thyroid pills forever. Most choose ablation over surgery. It's a choice.

Ultimately, the goal of hyperthyroidism therapy is to put the thyroid function (at least the thyroid blood levels) back to a normal range. All three of these therapies can do that, but each is also more likely to cause loss of thyroid function. It's often just a matter of how long that takes. Any person with hyperthyroidism needs close and careful follow up by an endocrinologist, often every month at the beginning until stability in thyroid blood levels can be achieved. But most often a low thyroid state happens (hypothyroidism) when properly treated. It's difficult to find a perfect balance of either surgery, medication or radio iodine that exactly counteracts the "runaway train" of an over active thyroid gland. There can be periods of time of normal thyroid levels after these therapies, but more often the gland stops making enough hormone and a deficiency happens, which then requires a daily thyroid replacement pill to be taken indefinitely.

If the thyroid gland is not too large when first diagnosed, there is a small possibility of the condition going away after a few years of anti thyroid pill therapy. Hence never requiring surgery or ablation. Such cases are not the norm however. This treat, wait and see approach must be carefully monitored by a thyroid specialist over time.

But treating low thyroid with one thyroid pill daily is superior to the alternative of many anti thyroid pills and ongoing risk of side effects to their use.

During the time a hyperthyroid person is actively symptomatic, an oral medication known as a beta blocker may be used to slow down a rapid heart rate caused by the high thyroid levels. Once the thyroid levels are back into a normal range, the need for the beta blocker pills goes away. If not stoppedproperly, a slow heart rate will occur (usually lower than 60 beats a minute). Beta blockers are not the same as anti thyroid medication (methimazole), so don't confuse them. They are often taken several times daily.

The cause of Graves' disease, a specific kind of overactive thyroid, is ultimately due to the immune system. In contrast to Hashimoto's disease, the immediate cause of Graves' disease is the presence of antibodies (complex chemical molecules produced by white blood cells) that attach themselves to the "on switch" of the thyroid cells and essentially hijack the thyroid from its normal control systems. In fact, the natural hormone that activates the thyroid gland, called thyroid stimulating hormone (or TSH for short) is totally turned off and not measurable in blood tests in persons with Graves' disease. This is one of the pieces of evidence that us endos use to make a proper diagnosis, along with measuring the level of the actual antibodies that are hijacking the gland.

Women with Graves' disease can have these antibodies in their blood even after they have been successfully treated with surgery or radioactive iodine therapy and back to normal. In about one in 100 such treated women, these thyroid stimulating antibodies can increase in amount during a pregnancy and cross from the mother's blood stream and into the fetus. This results in a baby being born with an significantly overactive thyroid gland. This is a rare occurrence but a serious one that requires specialist care in the newborn nursery or ICU.

Finally, many people fail to appreciate the impact of high thyroid levels on a person's mental health and ability to stay focused and relate well with others. Serious mental health problems, academic collapse, and serious risk taking behaviors and lapses in judgment can be the presenting signs of an overactive thyroid. It's important that parents and doctors remember this when evaluating a child, teen or adult with these kinds of problems.

Diabetes self care will absolutely suffer if the thyroid is improperly controlled or managed. Probably as much from the mental chaos this condition creates than it's effect on appetite (which increases dramatically but with little weight gain).

So...is this disorder genetic? In a word yes, but not in the way most people think about it. It's not unlike the genetics behind type 1 diabetes.

I hope this helps explain another hormone condition that can sometimes challenge those of us with diabetes. Please share this post freely with others.

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