Subacute Thyroiditis - Symptoms, Diagnosis and Treatment : Dr. Zaidi

Subacute thyroiditis is an uncommon disorder. It refers to inflammation of the thyroid gland. Usually it is triggered by an acute upper respiratory tract infection (URI), such as a common cold.

What Are The Symptoms of Subacute Thyroiditis?

Symptoms of Subacute Thyroiditis occur in two phases:

Phase 1: Symptoms of Hyperthyroidism

Pain in the thyroid area. At times, pain also radiates to jaw or the ear.
Restlessness
Palpitations
Insomnia/anxiety
Excessive perspiration
Intolerance to heat
Excessive weight loss despite good appetite

A few (6-12) weeks later, these symptoms subside on their own and symptoms of hypothyroidism develop.

Phase : 2 Symptoms of hypothyroidism

Fatigue, sluggishness
Weight gain
Intolerance to cold
Depressed mood

How Long Does It Take To Recover From Subacute Thyroiditis?

Recovery time from from subacute thyroiditis is about 3-6 months in most cases. However, some individuals – about 5% – may continue to experience symptoms of hypothyroidism for longer duration. A few may even develop permanent hypothyroidism. That’s why it is important to continue to monitor your thyroid functions periodically.

What Causes Subacute Thyroiditis?

The cause of subacute thyroiditis is viral, usually an upper respiratory tract infection (URI.) Consequently, there is structural damage to the thyroid gland. It’s like a tornado hitting a trailer park.

Normally, the thyroid gland stores a large amount of thyroid hormones to be released in small quantities over a period of time.

With the destruction of the gland caused by the tornado of subacute thyroiditis, the large quantities of the stored thyroid hormones gets released into the blood circulation. This causes the phase of hyperthyroidism.

The thyroid hormones remain in circulation for a few weeks (6-12 weeks) and so does the phase of hyperthyroidism.

After the tornado goes away, the thyroid gland starts to repair itself, but it takes a while.

During this period, there is shortage of thyroid hormones, which gives rise to the phase of hypothyroidism. This phase typically last a few weeks (6-12 weeks).

Eventually, in most cases, the thyroid gland restores back to normal, although some patients may become hypothyroid permanently.

Can COVID-19 Cause Subacute Thyroiditis?

Subacute Thyroiditis can develop during and after the illness of COVID-19. Several cases have been be described. One such case was reported from Singapore. This patient was hospitalized with COVID-19. During the hospital stay, the patient developed anterior neck pain and rapid heart beat. Thyroid function test showed hyperthyroidism. The patient was treated with prednisone with rapid recovery.¹

In another publication, endocrinologists from Italy reported four cases of Subacute Thyroiditis. These cases developed 16 to 36 days after the resolution of COVID-19. Main symptoms were neck pain, palpitations, fever and asthenia. Three patients received prednisone while one received Ibuprofen. Symptoms resolved within a few days of treatment. Six weeks later, all patients continued to be asymptomatic.²

Can COVID Vaccines Cause Subacute Thyroiditis?

Endocrinologists from Hacettepe University School of Medicine, Turkey report three cases of Subacute Thyroiditis triggered by the inactivated SARS-CoV-2 vaccine (CoronaVac®). All the patients were females and healthcare workers. They presented with anterior neck pain and fatigue, four to seven days after they received the COVID vaccine. Diagnosis was confirmed by the laboratory testing. The authors concluded these cases to be ASIA syndrome -Autoimmune/inflammatory Syndrome Induced by Adjuvants in the vaccines. ³

How to Diagnose Subacute Thyroiditis?

Diagnosis of subacute thyroiditis is a tricky one. Patients usually consult their family physicians, who often do not think about the possibility of subacute thyroiditis. Patients get placed on a variety of medicines to control their symptoms. When patients don’t get better, both patients and physicians feel quite frustrated. Usually, it takes an endocrinologist to diagnose subacute thyroiditis accurately.

Diagnostic Tests include:

Free T4, FreeT3, which are elevated.
Thyroid Antibody tests to differentiate from Graves’ disease.
Thyroid Radioiodine uptake and scan to differentiate from Graves’ disease.

Thyroid antibody tests

Your endocrinologist will order either a TSI – Thyroid Stimulating Immunoglobulins or TRAB – Thyrotropin Receptor Antibody test. Typically these antibodies are elevated in Graves’ disease but not in Subacute Thyroiditis.

Thyroid Radioiodine uptake and scan

Thyroid Radioiodine uptake and scan is the most useful tool in deciding whether hyperthyroidism is due to subacute thyroiditis or Graves’ disease. In subacute thyroiditis, radioiodine uptake is minimal. On the other hand, it is elevated in Graves’ disease.

The Thyroid Radioiodine uptake and scan should not be done if a patient is pregnant or breast-feeding.

Don’t rely on TSH, a test typically ordered by non-endocrinologists, because it lags behind about 6 weeks. Therefore, the results of TSH may be telling the story what happened 6 weeks ago, which may be quite misleading. Even otherwise TSH is a misleading test for thyroid function.

Treatment of Subacute Thyroiditis

In the majority of cases, subacute thyroiditis is a self-limiting disease. Therefore, no specific treatment is required. However, close monitoring is essential.

For pain in the thyroid area, NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) – such as ibuprofen, naproxen – can be taken. However, if pain is intolerable, a short course of oral steroids, such as prednisone, is quite helpful.

You can manage symptoms of hyperthyroidism with a Beta-Blocker such as atenolol or propranolol.

Magnesium glycinate can work well to control rapid heart rate, anxiety and insomnia.

Symptoms of hypothyroidism may require a short course of thyroid hormone replacement with T4 and T3.

Patient education and close monitoring of the thyroid functions are the most important component of the treatment.

In Conclusion:

Subacute Thyroiditis presents with the worrisome symptoms of anterior neck pain, palpitations, anxiety and weight loss, followed by symptoms of hypothyroidism – sluggishness, weight gain, and depressed mood. An endocrinologist can quickly make the diagnosis and reassure the patient. Prognosis is excellent in the vast majority of patients. A few individuals may develop permanent hypothyroidism. Physician should be vigilant to the possibility of Subacute Thyroiditis in COVID-19 patients.