Role of thyroid Doppler in differential diagnosis of thyrotoxicosis.

OBJECTIVE: To evaluate the role of thyroid blood flow assessment by color-flow Doppler ultrasonography in the differential diagnosis of thyrotoxicosis.

METHODS: Consecutive patients with thyrotoxicosis presenting to our center between June 2007 and March 2008 were included in the study. Clinical data were collected, and thyroid function tests including measurements of thyrotropin, total thyroxine, and total triiodothyronine were performed. Thyroid glands of all patients were evaluated with color-flow Doppler ultrasonography for size, vascularity, and peak systolic velocity of the inferior thyroid artery. Technetium Tc 99m pertechnetate scan was done when the diagnosis was not clear on the basis of clinical findings. Patients were divided into 2 groups for analysis: patients with destructive thyrotoxicosis and patients with Graves disease. Paired t tests and Fisher exact tests were used for statistical analysis.

RESULTS: A total of 65 patients participated in the study; 31 had destructive thyrotoxicosis and 34 had Graves disease. Thyroid blood flow, as assessed by peak systolic velocity of the inferior thyroid artery, was significantly higher in patients with Graves disease than in patients with destructive thyroiditis (57.6 +/- 13.1 cm/s vs 22.4 +/- 5.4 cm/s; P<.05). All patients with destructive thyroiditis had low peak systolic velocity of the inferior thyroid artery, and 32 of 34 patients with Graves disease had high peak systolic velocity. Color-flow Doppler ultrasonography parameters correlated significantly with pertechnetate scan results, demonstrating a comparable sensitivity of 96% and specificity of 95%.

CONCLUSIONS: Differentiating Graves thyrotoxicosis from destructive thyrotoxicosis is essential for proper selection of therapy. Assessment of thyroid blood flow by color-flow Doppler ultrasonography is useful in this differentiation.