Subacute thyroiditis and acute suppurative thyroiditis

Both subacute thyroiditis (SAT) and acute suppurative thyroiditis (AST) represent thyroid disorders that may lead to hyperthyroidism as a result of destructive thyroiditis. SAT is supposedly of (post-)viral origin and has a characteristic triphasic clinical course (hyperthyroidism, hypothyroidism, euthyroidism). Patients often suffer from local pain, fever or malaise, biochemical findings include elevated inflammation parameters and increased serum thyroglobulin and liver enzymes. Usually, focal or multifocal poorly defined hypoechoic areas and a decreased vascularity in Doppler studies can be found during ultrasound imaging, while tracer uptake is reduced in thyroid scintigraphy. Beta-blocking agents are used for symptom control during thyrotoxicosis, nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids are recommended for pain relief and control of inflammatory symptoms. Thyroidectomy may be necessary in severe cases. Furthermore, unclear cases of SAT should prompt liberal further investigation via fine needle aspiration to differentiate the disease from possible malignancies or AST. AST is a bacterial infection of the thyroid, whose development is supported by certain anatomical-structural predispositions. Clinically, patients experience sudden neck swelling, pain, fever, sore throat, dysphagia, and localized erythema. SAT also leads to increased inflammatory parameters, while a thyrotoxic phase is less common. During acute inflammation, abscess formation and its expansion can be demonstrated by thyroid ultrasound or neck CT scans. Therapeutically, immediate empiric antibiotic therapy as well as drainage of abscess formations is of utmost importance.