Master Subacute Thyroiditis Pathophysiology with Picmonic for Medicine

Subacute thyroiditis is largely self-limited. Self-limiting disease refers to a medical condition that resolves on its own without requiring significant medical intervention, although symptomatic management may be necessary. While Subacute thyroiditis thyroid gland recovers spontaneously over a few weeks to months. However, some patients experience relapses and permanent hypothyroidism occurs in 15% of cases.

Subacute thyroiditis, which involves inflammation of the thyroid, manifests as a triphasic response. Each phase varies in duration and includes the thyrotoxic, hypothyroid, and euthyroid phases.

The first phase of the triphasic response is referred to as the thyrotoxic phase. This phase typically last 2-8 weeks and is due to damage of the follicular cells and the release of pre-formed colloid or stored T3/T4.

The thyrotoxic phase is due to damage of the follicular cells and the release of stored T3/T4 (i.e. pre-formed colloid). When follicular cells are damaged due to inflammation, autoimmune attack, or infection as seen in subacute thyroiditis, they lose their structural integrity and release performed colloid into the bloodstream. This leads to a transit increase in thyroid hormones and depletion of stored colloid.

The thyrotoxic and hypothyroid phases typically last 2-8 weeks.

The second phase of the triphasic response is the hypothyroid phase, which can be permanent in ~15% of subacute granulomatous thyroiditis cases. The hypothyroid phase involves the depletion of pre-formed colloid along with the impaired synthesis of new thyroid hormones as a result of follicular cell damage.

The hypothyroid phase involves the depletion of pre-formed colloid and as a result leads to the impaired synthesis of new thyroid hormones (i.e. colloid) due to the damage of the follicular cells.

The thyrotoxic and hypothyroid phases typically last 2-8 weeks.

The last phase of the triphasic response - the euthyroid phase - involves recovery of thyroid functioning along with pathological changes no longer being visible in the thyroid gland.

The euthyroid phase involves the recovery of the thyroid along with pathological changes no longer being visible in the thyroid gland.