Table 6.8-3. Clinical phases of subacute thyroiditis (de Quervain thyroiditis)

Hormone levels

Iodine uptake

Clinical features

Phase 1

↑ FT4, ↑ FT3, ↓ TSH

Low

Thyrotoxicosis

Phase 2

Normal

Low

Euthyroidism

Phase 3

↓ FT4, ↓ FT3, ↑ TSH

High

Hypothyroidism

Phase 4

Normal

Normal

Euthyroidism

↑, increase; ↓, decrease; FT3, free triiodothyronine; FT4, free thyroxine; TSH, thyroid-stimulating hormone.