STUDIES ON THYROID VOLUME ESTIMATED BY ULTRASONOGRAPHY

Abstract

Changes in thyroid volume of patients with various thyroid diseases were evaluated and compared with those in circulating thyroid parameters. Studies were conducted on 160 patients with Graves' disease, 20 patients with Hashimoto's thyroiditis, 25 patients with simple goiter and 25 patients with thyroid tumor. Thyroid volume was measured by ultrasonography (thyroid volume = πabc/6, a : length, b : width, c : depth).In normal subjects (n=-20), thyroid volume ranged from 2.9 to 11.3ml (mean, 6.8ml). In simple goiter, thyroid volume ranged from 4.2 to 13.7ml (mean, 9.7ml). In untreated Graves' disease, thyroid volume ranged from 6.9 to 66.7ml (mean, 27.0ml). In untreated Hashimoto's thyroiditis, thyroid volume ranged from 4.3 to 120.0ml (mean, 31.8ml). In thyroid tumor, thyroid volume ranged from 7.4 to 25.8ml (mean, 13.5ml).In all the patients with Graves' disease as well as untreated patients, thyroid volume was significantly correlated with TBII (p<0.01) and Tg (p<0.01), but not with TSH, TSAb, MCHA or TGHA. In 11 patients, the mean thyroid volume decreased significantly after 1 year of therapy with methimazole (MMI, p<0.01), which is associated with decreasing serum TB II levels. Ten patients went through transient hypothyroidism due to overdoses of MMI, and the mean thyroid volume increased significantly (p<0.01) with increasing serum TSH levels. The mean thyroid volume of patients with sustained remission (n= 7) was significantly less than that of patients with relapse (n = 5) at the time MMI was stopped (p<0.05).Six patients with Hashimoto's thyroiditis were treated with T3, while 14 patients were treated with T4. In patients given T3 or T4 therapy, the mean thyroid volume decreased significantly after 6 months (p<0.01). In patients with euthyroid Hashimoto's thyroiditis, as well as those with hypothyroidism, the mean thyroid volume decreased significantly after thyroid hormone therapy (p<0.01).In conclusion, it is suggested that TSH and TSH receptor antibodies (TRAb) may stimulate thyroid growth. In addition, circulating Tg levels reflect thyroid volume in Graves' disease. It is also suggested that measurement of thyroid volume is useful in predicting remission in Graves' disease. In both patients with euthyroid Hashimoto's thyroiditis and hypothyroidism, thyroid volume decreased significantly after T3 or T4 therapy.