While over 12% of the United States population will develop a thyroid condition in their lifetime, many Americans do not fully understand the potential complications that can arise when thyroid disease goes untreated.

The thyroid is a small gland that plays a crucial role in several bodily processes, and any level of dysfunction can lead to various adverse effects. Thyroid disease can lead to severe and life-threatening outcomes if left untreated.

What Does Thyroid Disease Do to the Body?

Thyroid disease generally refers to thyroid dysfunction; however, not all cases are the same. There are two primary forms of thyroid disease: hypothyroidism and hyperthyroidism.


In patients with hyperthyroidism, the thyroid over-produces T3 (triiodothyronine) and T4 (thyroxine), collectively referred to as thyroid hormone. These hormones are responsible for managing the body’s metabolism, which is the conversion of food to energy. When the thyroid produces excess thyroid hormone, the body’s metabolism increases, causing several unwanted effects, such as:

  • Weight loss
  • Tachycardia (rapid heartbeat)
  • Arrhythmia (irregular heartbeat)
  • Heart palpitations
  • Anxiety and irritability
  • A tremor in the hands or fingers
  • Increased perspiration
  • Altered menstrual cycle
  • Increased heat sensitivity
  • Goiter (enlarged thyroid)
  • Fatigue and weakness
  • Sleep disruptions
  • Thinning skin and hair
  • More frequent bowel movements


Hypothyroidism is the opposite of hyperthyroidism. In patients with hypothyroidism, the thyroid gland produces too little thyroid hormone, which slows the metabolism and other bodily processes.

There are several causes of hypothyroidism, such as Hashimoto’s thyroiditis, an autoimmune disorder that causes the immune system to attack the thyroid. Some of the most common symptoms of hypothyroidism include the following:

  • Fatigue and weakness
  • Constipation
  • Weight gain
  • Increased cold sensitivity
  • Puffy face or eyes
  • Elevated cholesterol levels
  • Muscle aches or stiffness
  • Joint pain or stiffness
  • Hoarseness or loss of voice
  • Dry skin
  • Thinning hair
  • Low heart rate
  • Depression
  • Memory impairment
  • Goiter (enlarged thyroid)

How Thyroid Disease Can Be Life-Threatening

While most patients respond well to thyroid treatment if their thyroid disease is detected early, the American Thyroid Association estimates that 60% of all patients with thyroid disease go untreated or undetected. If this happens, thyroid disease can worsen progressively, ultimately leading to life-threatening complications.

Both hyperthyroidism and hypothyroidism can be deadly if left untreated. Some of the most dangerous thyroid disease complications include:

Heart Issues

Heart issues are particularly prevalent in patients with hyperthyroidism, as excess thyroid hormones can significantly increase the patient’s resting heart rate, cause an irregular heartbeat, and increase blood pressure. Combined, these effects can dramatically increase the patient’s risk of a heart attack or stroke long-term.

While hyperthyroidism is more likely to lead to heart problems, hypothyroidism can also cause cardiovascular issues. The decrease in muscle tone and cellular energy associated with hypothyroidism can lead to a slowed heart rate and make the pumping of blood less effective, stressing the heart.

Hypothyroidism is also associated with an increased risk of elevated blood cholesterol levels, which may increase the patient’s risk of heart disease.

Thyrotoxic Crisis

A thyrotoxic crisis, also known as thyrotoxicosis, occurs when the levels of thyroid hormone in the body are too high. While this is a relatively rare complication (affecting 2% of women and 0.2% of men), it can also be life-threatening in severe cases. Thyrotoxic symptoms are usually the same as those associated with hyperthyroidism but are significantly more severe.

Patients suffering from a thyrotoxic crisis will experience an extremely rapid heartbeat, elevated blood pressure, a very high fever, profound confusion, and gastrointestinal distress. Often, the patient will also lose consciousness.

These symptoms typically appear rapidly, often in as little as a few hours or days. The condition requires immediate treatment; untreated, a thyrotoxic crisis often leads to death. The combination of a rapid heartbeat, elevated blood pressure, and the often-present heart palpitations and atrial fibrillation can cause heart failure.

Myxedema Crisis

If hypothyroidism goes untreated for an extended period, the patient may experience a myxedema crisis (also called a myxedema coma), which occurs when the body can no longer tolerate the inadequate levels of thyroid hormone due to an underactive thyroid.

Since thyroid hormone plays a crucial role in cell metabolism, a lack of thyroid hormone can lead to problems with oxygen circulation in various body parts and slow the metabolism to a dangerous level.

As a result, a myxedema crisis is life-threatening and requires immediate treatment; patients may experience a low body temperature, changes in cognition, respiratory depression, shock, seizures, heart failure, and coma.

Women and patients over 60 are more likely to experience a myxedema crisis, though pregnancy and concurrent illness are also risk factors.

Thyroid Disease Treatment Options

Fortunately, patients who recognize the signs of thyroid disease early have plenty of effective treatment options to help them reduce symptoms and prevent life-threatening complications. For patients with hyperthyroidism, some of the most common treatment options include:

Antithyroid Drugs

Antithyroid drugs reduce the amount of thyroid hormone circulating in the body. There are two main classes of antithyroid drugs that are differentiated by their mechanism of action: thionamides, which reduce the amount of thyroid hormone created, and iodides, which reduce the amount of thyroid hormone released.

The most common antithyroid drug is methimazole, which falls into the thioamide group. In some circumstances, particularly during the first trimester of pregnancy, propylthiouracil (PTU) may be used instead due to a slight increase in the likelihood of congenital disabilities associated with methimazole.

Radioactive Iodine Treatment

Radioactive iodine treatment, also called radioiodine ablation, is another possible treatment course for more severe cases of hyperthyroidism. It is also used in patients with cancerous thyroid nodules.

With radioactive iodine treatment, the patient orally consumes a dose of radioactive iodine. Since the thyroid needs iodine to produce thyroid hormone, it concentrates iodine more efficiently than any other organ; as a result, the thyroid absorbs the radioactive iodine. Once absorbed, the radioactive iodine damages or destroys the thyroid, which reduces or eliminates the production of endogenous thyroid hormone.

This treatment is generally well-tolerated, though it may result in hypothyroidism if the dose is large enough to destroy the thyroid. In this case, the patient will likely have to take exogenous thyroid hormones to maintain proper hormone levels.


A thyroidectomy is a surgical procedure to remove the thyroid. This treatment is typically reserved for pregnant patients, breastfeeding, or those who don’t want radioactive iodine therapy. Patients who undergo a thyroidectomy will need to take exogenous thyroid hormones.

Hypothyroidism Treatment

Compared to hyperthyroidism, hypothyroidism is considerably easier to treat. Typically, hypothyroidism treatment involves taking thyroid hormone replacement drugs, which function the same as naturally-produced hormones and reduce or eliminate hypothyroidism symptoms.

The most commonly-used thyroid hormone replacement is levothyroxine, which replaces the T4 thyroid hormone. Sometimes, patients will also need T3 hormone replacement in conjunction with levothyroxine.

Thyroid Doctor Order an Ultrasound

Thyroid Disease Treatment at Associated Endocrinologists

While thyroid disease can be life-threatening if left untreated or improperly managed, patients can live healthy, everyday lives with a dysfunctional thyroid if they seek early treatment. Thyroid disease will progressively worsen without adequate treatment, so it is vital to identify the signs of thyroid disease when they occur to reduce your likelihood of experiencing severe complications.

Physicians at Associated Endocrinologists have been helping patients with thyroid disorders live healthy, normal lives since 1984. Our physicians have received numerous awards from endocrinology healthcare societies, authored over 100 medical journal articles, and completed fellowships at prestigious institutions like the University of Michigan and Northwestern.

We offer the latest groundbreaking advances in thyroid treatment, such as radioactive iodine therapy, allowing you to receive the best possible course of treatment from highly experienced and qualified practitioners.

If you are experiencing signs of thyroid disease or believe you may be developing hypothyroidism or hyperthyroidism, call Associated Endocrinologists today at (248) 206-3242 and schedule an initial consultation.

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