Thyroid gland is a very important gland in the body due to its important function related to growth and metabolism. Thyroid gland can be affected by many condition like hypo- or hyper function of the gland, tumour, goitre and also affected by autoimmune disorders. Silent thyroiditis (ST) is one such autoimmune disease caused due to attack of the body's immune system on cells of the thyroid gland.
What is Silent Thyroiditis?
Silent thyroiditis is a type of disorder of the thyroid gland. Thyroiditis means inflammation of the thyroid gland and is often painful. In Silent Thyroiditis, there is no pain caused to the thyroid gland. Hence, it is called as 'Silent or Painless Thyroiditis'. The hallmark features of silent thyroiditis are the absence of thyroidal pain or tenderness and a markedly reduced radioactive uptake.
The other synonyms for Silent thyroiditis are Lymphocytic thyroiditis, Subacute lymphocytic thyroiditis.
Symptoms of Silent Thyroiditis
Hyperthyroidism (over-activity of thyroid gland) lasts for 3 months or less and the associated symptoms are:
- Weight loss
- Increased sensitivity to heat and excessive perspiration
- Mood changes such as irritability and nervousness
- Rapid heart palpitations
- Irregular periods in women
- Protrusion of eyes (mild)
- Increased hunger.
This state is followed by hypothyroidism (less activity of thyroid gland) and is characterized by the following symptoms:
- Weight gain
- Increased sensitivity to cold
- Mild enlargement of thyroid gland
- Dry skin and hair loss
- Irregular periods in women.
The symptoms of hypothyroidism persist till the thyroid gland becomes normal again. In some people, only symptoms of hypothyroidism are observed.
Prevalence Rate of Silent Thyroiditis
It is the least common type of thyroiditis. It affects middle aged women more than men. Individuals of all ethnic and racial groups are affected.
Prognosis of Silent Thyroiditis
Silent thyroiditis has a good prognosis. This disorder is self limiting and the recovery is within 1 year. However, in very few cases the hypothyroid state may not come to normal euthryoid state. In such cases, the patients need to be treated for hypothyroidism.
Causes of Silent Thyroiditis
The exact cause of Silent thyroiditis is not known till date. It is believed to be an autoimmune disease.
Pathophysiology of Silent Thyroiditis
The immune system generates antibodies (auto-antibodies) against thyroid gland. This attack leads to inflammation (swelling) of the thyroid. During this phase, the thyroid gland excessively secretes its hormones into the blood and shows symptoms of hyperthyroidism. After 3 months the thyroid gland gets depleted of its hormones and now shows symptoms of hypothyroidism. In most cases it returns to its normal euthyroid state and starts performing normal functions.
Risk Factors of Silent Thyroiditis
Risk factors associated with Silent Thyroiditis include:
- Female gender
- Family history
- May occur in patients with Systemis Lupus Erythematosus (SLE)
- Hodgkin lymphoma cancer patients who have been given radiation therapy
- Stoppage of steroid therapy
- Patients who have undergone surgical removal of the adrenal gland
- Patients who had lithium treatment.
Complications of Silent Thyroiditis
Silent thyroiditis is a self-limiting medical condition. Although in some cases complications arise when thyroid functions do not return to the normal and hypothyroidism persists permanently.
Diagnosis of Silent Thyroiditis
The clinical diagnosis of silent thyroiditis is performed as follows:
- Typical physical examination of:
- Blood tests to determine levels of T3, T4 and TSH hormones.
- Imaging techniques such as
- Ultrasound of Thyroid gland
- Radioactive uptake of iodine by thyroid gland
Treatment of Silent Thyroiditis
The symptoms of Silent Thyroiditis are mild and it is usually a self-limiting disorder, hence it does not require any treatment and only regular follow up is recommended.
In some exceptional cases treatment is required. The treatment options for Silent Thyroiditis are as follows:
- In case of increased palpitations, beta-blockers are administered to reduce rapid heart rate.
- In case of hypothyroidism, levothyroxine drug is given to bring the thyroid hormone levels to the normal.
- In some cases of hypothyroidism, thyroid replacement therapy may be required.
Prevention of Silent Thyroiditis
The cause of silent thyroiditis is unknown. Hence, currently there is no known preventive method available.
Coping with Silent Thyroiditis
During treatment of a patient with silent thyroiditis, bed rest is recommended. In such situations, presence of a health care provider who can give emotional support is helpful.
The mechanisms underlying pathogenesis of silent thyroiditis need to be thoroughly investigated. This approach will enable better treatment and management of these patients.