[Frequency of hypothyroidism after De Quervain thyroiditis and contribution of ultrasonographic thyroid volume measurement].

Subacute thyroiditis conventionally recovers without after-effect. Nevertheless some data relate a 5 to 9% occurrence of final hypothyroidism 6 months after the acute stage. We herein studied end-stage hypothyroidism occurrence and effect of thyroid volume alterations on hormonal course during thyroiditis. Twenty-nine cases of subacute thyroiditis were studied. Final thyroid function remained normal in 15 patients (51%) and undetermined in 5 patients (17%). Final hypothyroidism (TSH: 4.5-14.5 microU/mL) occurred in 9 patients (31%). Mean thyroid volume was increased in acute stage in patients with final normal thyroid function (16.6+/-5.7cm(3)) and decreased by 63% during follow-up; final mean thyroid volume was 6.1+/-1.3cm(3). Mean thyroid volume was normal in acute stage in final hypothyroid patients (10.7+/-3.0cm(3)) and decreased by 72% during follow-up; final mean thyroid volume was 3.3+/-1.1cm(3). End-stage mean thyroid volume was significantly lower in final hypothyroid patients (p<0.05) compared to patients with final normal thyroid function. We conclude that the occurrence of final hypothyroidism is underestimated after subacute thyroiditis. Ultrasonographic follow-up might be helpful in the detection of final hypothyroid-risk patients: thyroid volume not increased in acute stage and lower than 5cm(3) during follow-up is one of the ultrasonographic features of these patients.