Subacute thyroiditis

Subacute thyroiditis (de Quervain's) may be caused by a viral infection of the thyroid gland. It has a seasonal and geographical distribution common to infections with mumps virus, coxsackievirus and echo virus.

Patients with this disorder usually have an acute phase of thyroiditis in which the gland may be painful and anti-thyroid antibodies may be present. In this phase, patients are thyrotoxic, with an elevated serum T4 and decreased radioiodine uptake.

Progressive euthyroid and hypothyroid periods of 4-8 weeks may follow before thyroid functions finally normalize. Subacute thyroiditis shows a rapidly enlarging thyroid gland and signs of thyroid dysfunction. It has an acute course and is often associated with pain and tenderness in the area of the gland. It is also accompanied by an elevated erythrocyte sedimentation rate. It can cause low-uptake toxicosis, in that it can produce elevated serum levels of thyroid hormones in the face of low to normal levels of radioactive iodine uptake.