The sonographical and functional sequelae of de Quervain's subacute thyroiditis: long-term follow-up

Abstract

Abstract. Fifty-three patients with subacute thyroiditis (SAT) were seen during the acute stage of the disease. HLA-Bw 35 was positive in 33 out of 39 tested patients. At first presentation, all examined patients (N = 23) had ultrasound abnormalities (generalized hypodensity, single or multiple hypodense areas). Serum T4 and/or T3 were increased in 24/52, free T4 in 11/23, and the TSH response to TRH was flat in 8/11 patients. Six of 12 in whom volumetry was performed had goitres. Thirty-seven patients were re-examined after a mean follow-up interval of 46.5 months. At this follow-up, serum T4, free T4 and T3 levels as well as the sonographically determined thyroid volume had decreased, but there was still abnormalities by ultrasound detected in 14/36 patients; 19.4% had focal sonolucent lesions, whereas the prevalence of such lesions was only 3.1% in asymptomatic controls. Three patients were subclinically hypothyroid at the follow-up, whereas all others were euthyroid. Patients with abnormal ultrasound findings were of the same age and had a similar thyroid size, but a slightly higher TSH and a significantly (P<0.02) lower free T4 than those with normal ultrasound findings. They also had a higher prevalence of thyroid autoantibodies in low titres. Serum thyroglobulin was elevated in more than half of the patients during the acute phase, but only in 1 out of 11 patients during follow-up. Thyroglobulin at the follow-up was not related to TSH, but there was a correlation with thyroid volume (r = 0.57). In conclusion, thyroid abnormalities regarding both function and ultrasound findings are sufficiently frequent after SAT to warrant close observation of the patient. Conversely, abnormal ultrasound findings and diminished thyroid function, when not explained by other factors, should suggest the possibility of past SAT.