Measurements of thyroid blood flow may help differentiate between thyroiditis and Graves’ disease as causes of hyperthyroidism
(July 2007)
The background of the study. Distinguishing between thyroiditis, particularly painless thyroiditis, and hyperthyroidism caused by Graves’ disease is important because their treatment is different. In this study, quantitative measurement of thyroid blood flow by ultrasonography was evaluated as a test for the differential diagnosis of these disorders.
How the study was done. The study subjects were 114 patients with hyperthyroidism and 25 normal subjects. All the patients had high serum free thyroxine (T4) and low serum thyrotropin (TSH) concentrations. Fifty-six (49 percent) had Graves’ disease, 28 (24 percent) had painless thyroiditis, and 30 (26 percent) subacute painful thyroiditis. Thyroid volume and blood flow were measured by ultrasonography.
The results of the study. The characteristics of the four groups, their standard test results, and the results of the quantitative measurements of thyroid blood flow are shown in the Table.
| Table. Demographic Characteristics and Mean Thyroid Test Results in 114 Patients with Hyperthyroidism and 25 Normal Subjects. |
| |
Graves’ Disease
(n = 56) |
Painless Thyroiditis
(n = 28) |
Subacute Thyroiditis
(n = 30) |
Normal Subjects
(n = 25) |
| Women/men |
45/11 |
22/6 |
24/6 |
20/5 |
| Serum free T4 (ng/dl) |
3.2 |
2.0 |
2.6 |
1.0 |
| Thyroid blood flow (%) |
15 |
0.8 |
0.9 |
0.8 |
All patients with Graves’ hyperthyroidism had high thyroid blood flow values (average, 15 percent), and all patients with painless thyroiditis and subacute thyroiditis had flow values <4 percent (average, 0.8 percent).
The conclusions of the study. Patients with thyroiditis can be distinguished from those with hyperthyroidism caused by Graves’ disease by quantitation of thyroid blood flow by ultrasonography.
The original article. Ota H, Amino N, Morita S, Kobayashi K, Kubota S, Fukata S, Kamiyama N, Miyauchi A. Quantitative measurement of thyroid blood flow for differentiation of painless thyroiditis from Graves’ disease. Clin Endocrinol (Oxf) 2007;67:41-5.
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