Patients will experience a hyperthyroid period as the cellular lining of colloid spaces fails, allowing abundant colloid into the circulation, with neck pain and fever. Patients typically then become hypothyroid as the pituitary reduces TSHproduction and the inappropriately released colloid is depleted before resolving to euthyroid. The symptoms are those of hyperthyroidism and hypothyroidism. In addition, patients may suffer from painful dysphagia. There are multi-nucleated giant cells on histology. Thyroid antibodies can be present in some cases. The clinical presentation during the hyperthyroid phase can mimic those of Diffuse Toxic Goiter or Graves' disease. In such cases, a radionuclide thyroid uptake and scan can be helpful, since subacute thyroiditis will result in decreased isotope uptake, while Graves' disease will generally result in increased uptake. Distinguishing between these two types of disease is important, since Graves' disease and Diffuse Toxic Goiter can be treated with radioiodine therapy, but subacute thyroiditis is usually self-limited and is not treated with radioiodine.
In the initial phase of damage to the gland, preformed thyroid hormone will 'fall out' of the damaged cells. This leads to symptoms and biochemistry of an overactive thyroid, with raised free T3 and free T4, and a suppressed thyroid stimulating hormone value. The damaged cells will no longer be able to take up iodine in order to manufacture further supplies of thyroid hormone, and thus in due course the patient comes to experience the symptoms of an underactive thyroid with low free T3 and free T4, and eventually increased TSH.
Diagnosis
With the standard overactive thyroid, iodine uptake into the thyroid is avid, whereas if the cells are damaged, then uptake is poor. In this way, if there is doubt about whether the patient has too much thyroid hormone because of de Quervain's thyroiditis, then measuring radio-iodine uptake or technetium uptake gives a clear cut answer as it will be higher than normal in standard thyrotoxicosis and lower than normal in de Quervain's.
It is sometimes called subacute thyroiditis, but there are other forms of subacute thyroiditis, subacute lymphocytic thyroiditis, postpartum thyroiditis, and autoimmune thyroiditis all of which, in contrast to de Quervain's, are typically painless or "silent". It is also sometimes called "painful subacute thyroiditis". This is in contrast to subacute lymphocytic thyroiditis, which is also sometimes called "painless thyroiditis".
