The functional outcome of patients with subacute thyroiditis

Abstract

Whether with the passage of time subacute thyroiditis leads to hypothyroidism remains to be determined. Therefore, we evaluated the thyroid function including TRH test of 66 patients with a previous history of subacute thyroiditis and age-matched control subjects with special reference to the measurement of inorganic iodide. The patients were divided into 3 groups according to time lapse since the occurrence. Group 1 consisted of 24 cases followed up for 4 to 24 months. Sixteen cases in group 2 had their courses from 2 to 5 years, and group 3 was composed of 26 cases over the past 5 to 30 years. We selected 169 subjects without history of subacute thyroiditis and divided them into three control groups matched for age, each corresponding to the patient groups (group 1a, 2b and 3c, respectively). 41.7% and 29.2% of cases in group 1 had high basal levels of serum TSH (greater than 3.6 microU/ml) and delta TSH (the increment of TSH after TRH, greater than 46.8 microU/ml). In group 2, levels of serum T3 and T4 returned to normal ranges. However, in group 3, significant higher elevations in TSH and delta TSH than those in group 3c were observed, and the T4, FT4, T3 and FT3 levels were lower than those of group 3c (p less than 0.01 and p less than 0.05, respectively). 42.3% of cases in group 3 showed high TSH, and there were 4 cases with clinical hypothyroidism. Among the cases studied, a significant negative correlation (p less than 0.01) between levels of TSH and T4 was observed, while a correlation between TSH and delta TSH was positive (p less than 0.001). High levels of serum inorganic iodide were observed in 6.1% of cases and a correlation between inorganic iodide and TSH was significantly positive (p less than 0.01) not only in patients with subacute thyroiditis, but also in the control subjects. Antithyroid autoantibodies were detected in 42.4% of all the cases with subacute thyroiditis and also in 45.6% of all the controls. In group 3, MCHA was detected in 64.5% of the cases, and the frequency was higher than that of group 3c as well as that of 25% in group 2 (p less than 0.01), respectively. In 15.4% of the cases in group 3, the titers of MCHA were more than 40(2), and the titers of MCHA were significantly higher in patients with a long-term period after the onset of subacute thyroiditis than those with a short-term period.(ABSTRACT TRUNCATED AT 400 WORDS)