Correlation of computerized gray-scale sonographic findings with thyroid function and thyroid autoimmune activity in patients with Hashimoto's thyroiditis.

PURPOSE

The objective of this study was to retrospectively assess whether computerized gray-scale sonography can allow objective measurement of thyroid echogenicity in patients with Hashimoto's thyroiditis (HT) at various functional stages of the disease.

METHODS

Of the 77 patients with HT who were included in our study, 28 had been euthyroid, 20 had had subclinical hypothyroidism, and 29 had had clinical hypothyroidism. Of those with clinical hypothyroidism, 6 had been untreated and 23 had been receiving L-thyroxine substitution therapy. Fifty volunteers without thyroid disease served as a control group. Thyroid echogenicity was evaluated by computerized gray-scale sonography as mean tissue density (MTD) +/- standard deviation; the echogenicity of the prethyroid muscles served as a control of the system variability.

RESULTS

The MTD was significantly lower for the patients with HT (15.9 +/- 4) than for the control subjects (24.3 +/- 3; p < 0.05). Moreover, a significant difference was found between the MTD values of euthyroid patients with HT (18.9 +/- 3.4) and hypothyroid patients with HT analyzed either as a group (14.3 +/- 3.8) or separately for subclinical hypothyroidism (14.9 +/- 3.8) and clinical hypothyroidism (13.9 +/- 3.7; p < 0.05). The lowest MTD was found in patients with untreated clinical hypothyroidism (11.1 +/- 4.3), with a significant difference (p < 0.05) compared to all other groups of patients. Untreated patients with clinical hypothyroidism also showed the highest mean anti-thyroid peroxidase autoantibody levels (1,286 +/- 177 IU/ml versus 570 +/- 489 IU/ml for L-thyroxine-treated patients; p < 0.05), although no correlation between the MTD values and anti-thyroid peroxidase autoantibody levels was found in any group of patients.

CONCLUSIONS

Computerized gray-scale sonography provides an objective measure of thyroid hypoechogenicity, which correlates well to the clinical stages of HT. Use of this modality may prove beneficial in the diagnosis and follow-up of patients with HT.