What are the other Names for this Condition? (Also known as/Synonyms)

• Medication-Induced Thyroiditis

What is Drug-Induced Thyroiditis? (Definition/Background Information)

• Thyroiditis is an inflammation of the thyroid gland from various causes, which results in a set of associated signs and symptoms. Drug-Induced Thyroiditis occurs secondary to the use of certain medication, as an adverse reaction of the body
• The offending medications causing the condition include certain antiarrhythmic medications, cytokine proteins, anti-viral drugs, and lithium drugs. Drug-Induced Thyroiditis may either result in an overactive or underactive thyroid gland (causing hyperthyroidism or hypothyroidism respectively)
• The signs and symptoms of Drug-Induced Thyroiditis depend on the clinical state of the condition but are generally mild. These may include pain, weight gain or loss, heat or cold intolerance, abnormal heartbeat, dry skin, fatigue, and mental health issues
• Stopping or discontinuing the use of such medications may decrease progression of Drug-Induced Thyroiditis and/or may result in resolution of the condition. The prognosis is good in a majority of cases with adequate treatment

Who gets Drug-Induced Thyroiditis? (Age and Sex Distribution)

• Drug-Induced Thyroiditis is an uncommon form of thyroiditis; only a small percentage of the population using the drugs develop this condition
• Individuals of all ages may be affected, although most cases are noted in adults
• Both males and females are affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Drug-Induced Thyroiditis? (Predisposing Factors)

The key risk factor for Drug-Induced Thyroiditis is the use of certain medications that cause the condition as a side effect. The medications observed to induce this abnormal thyroid condition may include:

• Amiodarone (antiarrhythmic medication)
• Cytokines (protein therapeutics)
• Interferons, used in treating some malignancies and viral infections
• Iodine-based drugs that are used to treat COPD and in contrast media (during radiology procedures)
• Lithium compounds (psychiatric therapy medications)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Drug-Induced Thyroiditis? (Etiology)

• Drug-Induced Thyroiditis develops from the use of certain medications/drugs that are administered for various health conditions
• It is believed that the offending drug potentially causes an abnormal cell-mediated immune response in the body (specifically affecting the function of the thyroid gland)
• Sometimes, the appearance of signs and symptoms due to the drug may not be observed immediately after starting the medication. The condition may arise after a period of time

What are the Signs and Symptoms of Drug-Induced Thyroiditis?

The signs and symptoms of Drug-Induced Thyroiditis may vary from one individual to another. It may also be mild or severe and may be related to the type and usage of the drug. The condition is known to get better after stoppage of the offending medication.

It is reported that individuals may present hyperthyroidism or hypothyroidism or both over a period of time. Some individuals have pain and swelling in the thyroid gland.

The associated signs and symptoms of hyperthyroidism may include:

• Sleeping difficulties including insomnia
• Excess sweating and intolerance to heat
• Increased to excessive hunger
• Irritation, restlessness, and nervousness
• Protrusion of the eyes
• Menstrual abnormalities in women; menstruation may be irregular or short
• Abnormal heartbeat rate including rapid heart rate
• Weight loss

The signs and symptoms associated with hypothyroidism may include:

• Difficulty concentrating or thinking
• Fatigue and tiredness
• Dry skin
• Hair loss, which may be in excess while showering
• Constipation or difficult bowel movements
• Weight gain that may be slow and gradual
• Heavy and irregular periods (in women)
• Abnormal sensitivity to cold; the affected individuals may not tolerate cold very well

The onset of Drug-Induced Thyroiditis may be slow or rapid. In some cases, it may not be immediately observed, but may take days and weeks (or even much longer) to manifest following intake of the medication.

How is Drug-Induced Thyroiditis Diagnosed?

The diagnosis of Drug-Induced Thyroiditis may involve the following tests and procedures:

• Complete physical examination with comprehensive evaluation of medical history (which includes the use of any drug/medication)
• Assessment of the signs and symptoms
• Blood tests to evaluate the levels of:
  • T3 and T4; thyroid hormones produced in the thyroid gland
  • Serum TSH 
  • Antithyroid peroxidase antibody (anti-TPO); antibodies against thyroid peroxidase, an enzyme in the thyroid gland
  • Antithyroglobulin antibody; antibodies interacting with thyroglobulin, a protein found on the thyroid cells
• Ultrasound scans of the thyroid gland
• Radioactive iodine uptake test
• Fine needle aspiration (FNA) biopsy or core biopsy of the thyroid gland, if needed

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Drug-Induced Thyroiditis?

Drug-Induced Thyroiditis usually does not present any significant complications. However, in some cases, the potential complications may include:

• Emotional stress
• Thyrotoxicosis, or the presence of excess thyroid hormones in the body tissues
• Complications arising from any underlying disorder if present

How is Drug-Induced Thyroiditis Treated?

Discontinuing the medication responsible for the side effect may result in a cure, or in improvement of the condition. If treatment is needed for Drug-Induced Thyroiditis, then the following measures may be considered:

• Administration of pain relievers and steroids (if necessary)
• Beta-blockers are known to relieve an elevated heart rate and excessive sweating, which are prescribed if needed
• Follow-up care with screening and check-ups are important at regular intervals

Note:

• Prescription anti-thyroid drugs for hyperthyroidism, or thyroid hormone replacement for hypothyroidism is generally not required
• If any of the prescribed treatment medication or methods cause new symptoms, then it is important to discontinue the medication and immediately inform the healthcare provider

How can Drug-Induced Thyroiditis be Prevented?

Current medical research has not established a method of preventing Drug-Induced Thyroiditis. However, the following measures may be considered to help lower one’s risk for the condition:

• Drugs that cause the condition may be discontinued or alternative medication prescribed
• Inform your physician if you are allergic to any medication
• Periodic monitoring or follow-up of the condition with the healthcare provider is recommended

What is the Prognosis of Drug-Induced Thyroiditis? (Outcomes/Resolutions)

• The prognosis for Drug-Induced Thyroiditis is usually good in many cases, upon discontinuation of the medication and adequate treatment of the condition, if necessary
• In a vast majority of individuals, the signs and symptoms last only for a short period of time; an immediate improvement is observed following discontinuation of the offending medication
• However, the prognosis may also depend upon the type of medication involved, the period of exposure to the offending medication, and severity of the symptoms

Additional and Relevant Useful Information for Drug-Induced Thyroiditis:

The following article links will help you understand thyroid-stimulating hormone (TSH), total T3, and total T4 laboratory tests:

http://www.dovemed.com/common-procedures/procedures-laboratory/thyroid-stimulating-hormone-tsh-test/

http://www.dovemed.com/common-procedures/procedures-laboratory/total-t3-blood-test/

http://www.dovemed.com/common-procedures/procedures-laboratory/total-t4-blood-test/