What are the phases of subacute thyroiditis in order?

• A. Thyrotoxic, Hypothyroid, Euthyroid
• B. Euthyroid, Thyrotoxic, Hypothyroid
• C. Hypothyroid, Euthyroid, Thyrotoxic
• D. Thyrotoxic, Euthyroid, Hypothyroid

Answer: (A)

In subacute thyroiditis, inflammation damages thyroid follicles and releases the stored hormone first. That spillover causes a thyrotoxic (hyperthyroid) phase with high circulating thyroid hormone and suppressed TSH. As the hormone stores are exhausted and the gland’s function is impaired during ongoing inflammation, a hypothyroid phase follows, characterized by low thyroid hormone levels and elevated TSH. Over time, the gland heals and returns to normal function, bringing the patient back to a euthyroid state. This progression matches the typical lab pattern: low TSH with high hormones in the thyrotoxic phase, then high TSH with low hormones in the hypothyroid phase, and finally normal labs during recovery.