COVID-19-associated thyroid diseases

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mitra Chitsazan, M.D.[2]


Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus named for the similarity of its symptoms to those caused by the severe acute respiratory syndrome. Coronavirus disease 2019 (COVID-19) has been considered a global pandemic since its first emergence in Wuhan, China. On March 12, 2020, the World Health Organization declared the COVID-19 outbreak a pandemic.COVID-19 has been found to affect several organs and body systems, including the endocrine system, with short-term and possible long-term consequences. Recent data shows that COVID-19 patients have experienced a range of thyroid diseases.

Historical Perspective


There is no established system for the classification of COVID-19-associated thyroid disorders.


The exact pathogenesis of COVID-19-associated thyroid diseases is not fully understood. However, the following hypotheses have been suggested for the development of thyroid dysfunction in COVID-19 patients. [3] [4] [5] [6] [7] [8]


Coronavirus disease 2019 (COVID-19) caused by a novel coronavirus called SARS-CoV-2 is the cause of COVID-19-associated thyroid diseases. To read more click here

Differentiating COVID-19-associated thyroid diseases from other Diseases

Epidemiology and Demographics

Risk Factors

There are no established risk factors for COVID-19-associated thyroid diseases.


There is insufficient evidence to recommend routine screening for COVID-19-associated thyroid diseases.

Natural History, Complications, and Prognosis

A number of observational studies have shown that COVID-19 infection may be linked to some thyroid diseases, including: [2] [9] [10] [11] [12] [13] [14] [15] [15] [16] [2]

  • Prognosis has generally been good in most cases of COVID-19 patients with hyperthyroidism/hypothyroidism.
    • In a patient with subacute thyroiditis, the thyroid function and inflammatory markers normalized in 40 days. [2]
  • In a study on 154 COVID-19 patients, Low fT3 (i.e., euthyroid sick syndrome) was associated with higher mortality and increased IL-6, suggesting poor prognosis in these patients. [17]


Diagnostic Study of Choice

The diagnosis of COVID-19-associated thyroid diseases is made based on the thyroid function test (TFT), which measures serum levels of triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH).

History and Symptoms

The symptoms of clinical hyperthyroidism in COVID-19 patients are similar to hyperthyroidism in the general population. The most common symptoms include:

The symptoms of clinical hypothyroidism in COVID-19 patients are similar to hypothyroidism in the general population. The most common symptoms include:

If accompanied by thyroiditis:

Physical Examination

The most common physical examination findings in patients with hyperthyroidism include: [18]

The most common physical examination findings in patients with hypothyroidism include:

Laboratory Findings

The laboratory findings in hyperthyroidism are:

  • Elevated levels of serum thyroxine (T4) and triiodothyronine (T3).
  • Undetectable serum TSH.
  • Total T4 and T3 measurements are influenced by multiple conditions affecting serum thyroxine-binding globulin (TBG). Thus, the measurement of free thyroid hormones; free T4 (FT4) and free T3 (fT3), is the gold standard for the diagnosis of Graves' disease.[19]
  • Antibodies against the TSH receptor (TRAbs) are pathognomonic for Graves' disease. They are detectable in the serum of about 98% of untreated patients.[20] Detection of TRAbs rules out other causes of thyrotoxicosis.[21]
  • Anti-thyroid peroxidase (TPO) and antithyroglobulin (Tg) antibodies are also detectable in many patients with Graves' disease, but it is not recommended to measure these antibodies for diagnosis in all patients.

The laboratory findings in hypothyroidism are:

The laboratory findings in euthyroid sick syndrome are:

Euthyroid sick syndrome T3

(80-180 ng/dl)


(4.6-12 ug/dl)


(0.7-1.9 ng/dl)


(0.4 to 4.0mIU/L)

Reverse T3

(90 to 350pg/mL)

Mild euthyroid sick syndrome N N N
Moderate euthyroid sick syndrome N N/↓ N/↓
Severe euthyroid sick syndrome N/↓
Recovery N/↓ N N N N/



Echocardiography or Ultrasound

CT scan

  • There are no CT scan findings associated with COVID-19-associated thyroid diseases.


  • There are no MRI findings associated with COVID-19-associated thyroid diseases.

Other Imaging Findings

Thyroid ultrasound

  • Thyroid ultrasound may help diagnose Graves's disease. Typically, the thyroid pattern in Graves' disease is hypoechoic. Thyroid ultrasound gives an accurate estimation of the thyroid size, which is important in planning the therapeutic management and allows the detection of thyroid nodules that may not be palpable on physical examination.

Color flow Doppler

  • Color flow Doppler (CFD) estimates the blood flow which, in hyperthyroid Graves' disease patients, is typically increased within the thyroid gland.
  • CFD can be useful in the differential diagnosis of Graves' disease and other causes of thyrotoxicosis characterized by a low blood flow to the thyroid, such as factitious thyrotoxicosis, painless and subacute thyroiditis. [24]

Other Diagnostic Studies

Radioactive iodine uptake

Thyroid Disease TSH receptor antibodies Thyroid Ultrasound Color flow Doppler Radioactive iodine uptake/Scan Other features
Graves' disease + Hypoechoic pattern Ophthalmopathy, dermopathy
Toxic nodular goiter - Multiple nodules - Hot nodules at thyroid scan -
Toxic adenoma - Single nodule - Hot nodule -
Subacute thyroiditis - Heterogeneous hypoechoic areas Reduced/absent flow Neck pain, fever, and elevated inflammatory markers
Painless thyroiditis - Hypoechoic pattern Reduced/absent flow Symptoms and signs of hypothyroidism
Hashimoto's thyroiditis - Diffusely enlarged thyroid gland with a heterogeneous echotexture Normal early stages: may show increased uptake, late stages: single or multiple areas of reduced uptake (cold spots) -
  • To view other diagnostic studies for COVID-19, click here.


Medical Therapy

  • Treatment of COVID-19-associated thyroid diseases generally depends on the presentation of thyroid disease.
  • No specific treatment has been reported for COVID-19-associated thyroid disease.


Surgery is not a treatment option for patients with COVID-19-associated thyroid diseases.

Primary Prevention

There are no established measures for the primary prevention of COVID-19-associated thyroid diseases.

Secondary Prevention

There are no established measures for the secondary prevention of COVID-19-associated thyroid diseases.


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