What thyroid disorders can occur while taking amiodarone?

Against the background of taking medications, pathological reactions may appear in the form of allergic reactions and organ dysfunctions.

So, amiodarone is known in medicine as a drug that can affect the function of the thyroid gland, enhancing or weakening its work. When taking amiodarone, patients should be advised of the importance of monitoring their blood thyroid hormone levels every six months.

Amiodarone. The benefits and harms of amiodarone for the body

Amiodarone is a class 3 antiarrhythmic drug that contains 74 mg of iodine per tablet. The metabolism of amiodarone releases about 7 mg of iodine per day.

 Amiodarone is used to treat heart rhythm disorders such as ventricular arrhythmia, supraventricular tachycardia, atrial fibrillation.

Amiodarone is able to accumulate in parenchymal organs and remain in the body for a long time. The half-life of amiodarone ranges from 22 to 100 days. Thus, after discontinuation of this drug, the products of its metabolism remain in the body for a long time.

Pathogenesis of the development of thyroid function disorders against the background of taking amiodarone

Amiodarone blocks the organization of iodine and disrupts the synthesis of thyroid hormones. This is called the Wolf effect – Chaikova.

In addition to hypothyroidism, amiodarone can also provoke thyrotoxicosis against the background of a specific inflammation of the thyroid gland or the development of "iodine - basedova", inhibits the synthesis of T4, stimulates the release of TSH.

There are 2 types of thyrotoxicosis while taking amiodarone:

• Type 1 - appears in patients who already had thyroid disease. In such cases, an additional load of iodine activates the processes of biosynthesis and secretion of gland hormones.
• Type 2 – appears against the background of the destruction of previously unaltered gland tissue with excessive intake of iodine, which is accompanied by the release of a large amount of thyroid hormones into the blood.

Each type of thyrotoxicosis has its own clinical picture and treatment.

Symptoms of amiodarone-induced thyroid disorders. Thyrotoxicosis manifestations

In the clinical picture of thyroid dysfunction while taking amiodarone, one can see signs of both hypothyroidism and thyrotoxicosis.

With the development of hypothyroidism, patients experience drowsiness, dry skin, chilliness, increased fatigue, a tendency to constipation, bradyarrhythmia and edematous syndrome.

With the development of thyrotoxicosis, weight loss, muscle weakness, tremor and subfebrile condition are observed. On the part of the heart, there is a refractoriness of tachyarrhythmia to the treatment, progression of chronic heart failure and deterioration of hemodynamics.

Diagnosis of hypothyroidism and thyrotoxicosis while taking amiodarone

Hypothyroidism in patients receiving amiodarone appears faster than thyrotoxicosis. Thyrotoxicosis from taking amiodarone is characterized by a late onset of symptoms, even one and a half years after drug withdrawal.

When symptoms are detected, thyroid hormone levels should be checked. In laboratory studies, hypothyroidism has an increase in TSH and a decrease in free T4.

Also, in order to clarify the diagnosis, ultrasound and scintigraphy are done. Differential diagnosis is carried out between two types of thyrotoxicosis and other pathologies of the thyroid gland, which are accompanied by thyrotoxicosis.

The first type of thyrotoxicosis is characterized by a history of multinodular toxic goiter or Graves' disease – Basedova. Palpation reveals a goiter. The blood flow in the gland is increased or normal. Treatment consists of thionamides and potassium perchlorate.

For the second type, the gland is not enlarged, there were no diseases of the gland, and the gland was not changed on ultrasound. But the blood flow in it is reduced. The condition requires treatment with glucocorticoids.

How is thyrotoxicosis treated while taking amiodarone?

If such disturbances are detected from taking amiodarone, it should be discontinued and replaced with another drug for the treatment of rhythm disturbances. After discontinuation of the drug, self-recovery is possible  euthyroidism. If it is impossible to stop amiodarone, it is recommended to take levothyroxine sodium if hypothyroidism is detected.

For the treatment of thyrotoxicosis, the first step is to decide on the abolition of amiodarone.

Tyrotoxicosis type 2 treatment can be surgical  in the absence of the effect of treatment for several months, as well as the progression of chronic heart failure and tachysystole.