Can Amiodarone Cause Thyroid Problems?

Is There A Connection Between Amiodarone And Thyroid Disorders?

The Thyroid is an overlooked gland, part of the endocrine system, which has several important functions to perform. This gland produces two essential hormones1, often referred to as T3 and T4. Both hormones contribute to a number of functions that the human body cannot survive without – including cellular metabolism.

The primary functions of these hormones are to ensure temperature regulation in the body is functioning optimally, as well as to regulate a patient’s heart rate and ensure proper metabolism.

Disorders affecting the thyroid gland have become relatively common today. The two primary types of disorders that healthcare publications tend to focus on include Hyperthyroidism, an overactive thyroid gland, and Hypothyroidism, an underactive thyroid gland.

Many elements have been associated with an increased risk of these diseases.

One relatively common cause is the administration of a drug known as Amiodarone. In this post, we’ll look at what Amiodarone is and why this drug can cause a patient to experience problems with their Thyroid.

We will also consider what appropriate steps can be taken to help reduce the effects that this medication may have on a patient’s thyroid gland.

What Is Amiodarone?

Amiodarone2 is a type of drug that is classified as an antidysrhythmic medicine. The drug is often sold under the brand names Nexterone, Cordarone, and Pacerone.

It is also called an anti-arrhythmic medicine. This pharmaceutical drug is used to treat medical conditions that cause a patient to experience irregular heartbeats. T

hese diseases can be fatal and cause the death of the patient without appropriate treatment. Examples of the disease include tachycardia and ventricular fibrillation that becomes persistent.

This drug is considered one of the most effective treatment options for these conditions. The medication helps to inhibit electrical signals that occur within the patient’s heart. These electrical signals cause the patient’s heartbeat to become irregular.

In turn, this helps to restore a normal heartbeat in the patient and helps to avoid further symptoms of the condition that is being treated with the medication.

Different forms of this medication are available, including a tablet, an injection, and an intravenous option.

The particular option that will be administered to a patient depends on a number of factors, including the disease that is being treated, how severe their symptoms are, and what type of Amiodarone drug the physician determines is most appropriate for the patient.

Thyroid-Related Complications Of Amiodarone

The problem with Amiodarone3 is that it contains a relatively large concentration of iodine. In fact, approximately 37% of this drug consists of iodine. Additionally, the chemical structure of Amiodarone is similar to the structure of T4, or thyroxine, which is one of the hormones produced by the thyroid gland.

Up to 17% of the iodine in this drug is released into the body as a biologically available form, often also referred to as being “free iodine.”

One dose of 200mg Amiodarone causes the patient’s body to be exposed to a level of iodine that is approximately 100 times higher than what is recommended on a daily basis. The free iodine then collects in adipose tissue, as well as in muscle tissue, the lungs, liver, and the patient’s thyroid gland – the fact that the iodine collects in the thyroid gland is where the problem comes in.

Once administered to the patient, the iodine that the medication causes to accumulate in the patient’s body can remain there for as long as nine months. In up to 18% of these patients, complications with the thyroid gland will develop.

The primary concern with Amiodarone regarding thyroid malfunction is Hyperthyroidism. Even though Hypothyroidism is also relatively common among the general population, this is not a particular concern when it comes to considering possible complications in patients who are given Amiodarone to treat an irregular heartbeat.

Hyperthyroidism refers to an overactive thyroid. In patients with this particular condition, the thyroid gland would produce an excess number of thyroid hormones.

Another condition that can develop as a complication of Amiodarone is thyrotoxicosis. This condition refers to an excessive number of thyroid hormones accumulating in tissues throughout the body.

When these conditions develop due to the administration of Amiodarone, then the patient will be diagnosed with either Amiodarone-induced thyrotoxicosis or Amiodarone-associated hyperthyroidism.

How To Recognize The Symptoms Of Thyroid Problems

Individuals who are taking Amiodarone should be wary of the fact that thyroid problems can develop with the use of this medication.

This is especially important for women as the prevalence of hyperthyroidism and other thyroid-related disorders are more prevalent among female patients.

Education about symptoms associated with the particular conditions that may develop as a complication of this medication can help a patient identify the problem early. With early recognition of these symptoms, the patient can obtain adequate treatment to help prevent the disorder from becoming more serious and resulting in possibly dangerous events.

Symptoms of Hyperthyroidism

Hyperthyroidism is also called overactive thyroid. This condition develops when the thyroid gland becomes overactive and produces an excessive amount of hormones – including thyroxine and triiodothyronine.

While the body requires a healthy supply of these hormones, too much of them can lead to a great number of potential adverse effects in the body and also result in the development of various symptoms.

Let’s take a look at some of the symptoms that patients need to be aware of to ensure they can identify symptoms associated with hyperthyroidism4 when they start to develop.

  • A sudden reduction in weight is one of the most common symptoms.
  • As weight reduces, the patient may also experience an increase in their appetite.
  • Tachycardia, a condition where the patient’s heartbeat becomes rapid, may also occur.
  • Bowel movements may become more frequent than before, which occurs due to the significant increase in metabolism.
  • Muscle weakness is relatively common among patients with hyperthyroidism. Fatigue is also not uncommon.
  • Sleeping difficulties, which may include symptoms associated with insomnia, may develop.
  • The patient may become more sensitive to warm temperatures.
  • Increase in sweating.
  • The patient’s hair may become brittle and fine. Their skin may also start to become thin.
  • Among female patients, menstrual patterns may be changed.
  • A goiter may also develop, which refers to the thyroid gland that becomes enlarged.

Symptoms of Thyrotoxicosis

Thyrotoxicosis refers to the excessive accumulation of thyroid hormones in a patient’s body. In particular, this condition usually causes a large amount of TSH, also known as Thyroid Stimulating Hormone, to be present in the bloodstream of the patient.

It is important to understand that Hyperthyroidism is a particular cause of Thyrotoxicosis5. Thus, when the patient develops Hyperthyroidism while taking Amiodarone, they are at an increased risk of developing Thyrotoxicosis.

Apart from Hyperthyroidism, however, other issues can also lead to this condition – including Thyroiditis, a condition where the thyroid gland becomes inflamed. This can occur when an excessive dosage of thyroid drugs are taken – which is a concern due to the fact that Amiodarone has a chemical structure that is, in some ways, similar to one of the hormones secreted by the thyroid.

Diagnosing Thyroid Disorders In Patients Who Take Amiodarone

When a patient finds that they are showing signs of complications associated with Amiodarone, such as symptoms of Hyperthyroidism or Thyrotoxicosis, then they should see a doctor. The doctor will be able to conduct a physical examination and ask the patient about the symptoms they are experiencing.

This will help the doctor determine if the patient may have developed one of these thyroid disorders.

A physical examination alone is never enough to provide a diagnosis of these complications associated with Amiodarone. Thus, the doctor will have to request certain tests to help make a final diagnosis and to determine what exactly is causing the particular symptoms that the patient is experiencing.

To diagnose Hyperthyroidism6, blood tests will be required. The doctor will send the patient’s blood sample to an appropriate diagnostics laboratory, where certain tests can be conducted to help the doctor determine if the patient has this condition.

The first test that is recommended is a measurement of TSH levels in the patient’s blood. When a low level of TSH is detected, further tests will usually be ordered. This will include a measurement of:

  • Free T4
  • Free T4 index
  • Free T3
  • Total T3

These tests will help the doctor determine what type of Hyperthyroidism the patient has.

The data will also enable the doctor to provide a more appropriate treatment plan to the patient to ensure that the right dosage of medication can be provided to avoid complications caused by a dose that is too low or too strong for the patient.

Treating Thyroid Disorders In Patients Taking Amiodarone

Once a patient is diagnosed with Hyperthyroidism or another complication caused by Amiodarone, then a doctor will usually initiate treatment to address the overactive thyroid. Some physicians may choose to reduce the dosage of Amiodarone or even discontinue the use of this medication, but this is not always appropriate since the symptoms caused by conditions that were initially treated with the drug can lead to fatal complications.

Additionally, the iodine accumulation caused by Amiodarone will continue to be present in the patient’s body for an extended period of time, even when they no longer take the medication.

Different treatments have been suggested7 to address an overactive Thyroid. In the United States, the most common option for the treatment of Hyperthyroidism is radioactive iodine ablation. This is not the only treatment that can be used, however.

When Hyperthyroidism is caused by excessive production of hormones by the thyroid gland, then antithyroid drugs may also be an effective treatment option. Antithyroid drugs help to reduce the activity of the Thyroid gland, which leads to lower production of these thyroid hormones.

In severe cases and when other treatments do not seem to work well, then a surgical approach, known as surgical thyroidectomy, may also be advised. This is not the first line of treatment that should be used in the treatment of Hyperthyroidism, but rather a last resort in cases where initial treatments do not help to reduce thyroid activity to a level where thyroid hormone concentrations become closer to what is considered a “normal” range.

Early treatment of an overactive thyroid gland usually yields more successful results, which is why individuals undergoing treatment with Amiodarone should be educated on symptoms they should look out for – and know when they should seek advice from a healthcare provider.

Conclusion

Thyroid dysfunction, of which hyperthyroidism and hypothyroidism are the most common, can have serious complications when a patient is not treated promptly and with the correct dosage of the appropriate medications.

The high iodine content in Amiodarone has been shown to contribute to both of these thyroid disorders, and can often yield more serious effects as compared to thyroid dysfunction caused by other factors.

Frequent monitoring of the patient’s thyroid levels, as well as TSH levels, can help to recognize an increase or decrease in thyroid function early on. This will help to initiate treatment early and avoid the development of complications.

References

1 R.M. Sargis. How Your Thyroid Works. EndocrineWeb. https://www.endocrineweb.com/conditions/thyroid/how-your-thyroid-works

2 Amiodarone. RxList. https://www.rxlist.com/consumer_amiodarone_nexterone/drugs-condition.htm

3 M. Gopalan. Thyroid Dysfunction Induced by Amiodarone Therapy. 28 March 2017. https://emedicine.medscape.com/article/129033-overview?pa=FiNijA0VRqN0o691prc9oL57X4GWqxZ22XyXKYh2EPDY8dwKizxz%252FvARVFUN%252FjlMayY5xfOAE6eP10oSk6xjfcOTxXj1FB9%252Fm4TgsfVXs6o%253D#a4

4 Hyperthyroidism (overactive thyroid). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/hyperthyroidism/symptoms-causes/syc-20373659

5 Elizabeth N Pearce. Diagnosis and management of thyrotoxicosishttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC1476727/

6 S. De Leo, S.Y. Lee, and L.E. Braverman. Hyperthyroidism. HHS Public Access. 27 September 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5014602/

7 I. Kravets. Hyperthyroidism: Diagnosis and Treatment. American Family Physician Journal. 1 March 2016. https://www.ncbi.nlm.nih.gov/pubmed/26926973

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