Recent advances have provided a great variety of techniques designed to assess the normal and disordered physiology of the thyroid gland. By and large, these procedures supplement rather than replace one another, and, when employed together, they make possible an integrated analysis of diverse aspects of thyroidal function and the metabolism of iodine. Thus, it is possible to assess the avidity of the thyroid gland for iodine, the quantity of thyroid hormone produced, its rate of release from the gland, the rate of peripheral degradation of hormone, and the concentration and chemical nature of hormonal iodine in the blood.1,2 Subacute, giant cell, or de Quervain's thyroiditis is a disease which is puzzling both in its etiology and in its pathologic physiology. In this disease, commonly employed measures of thyroidal function frequently display a seemingly paradoxical divergence from normality. For example, although the thyroidal uptake of radioiodine is characteristically diminished,