Ultrasound and color-flow Doppler evaluation for the diagnosis of subclinical hyperthyroidism

Clinical significance, population screening and management of subclinical hyperthyroidism (SHyper) are still debated. Although the diagnosis of subclinical hyperthyroidism is, by definition, purely a biochemical one a conventional gray-scale sonography and, more recently, color-flow Doppler sonography (CFDS) have proven to be useful in obtaining information about thyroid morphology and function in thyroid disease, such as SHyper. The objective of this study was to evaluate, using CFDS, the presence and significance of changes in intrathyroidal blood flow and velocity in patients affected by SHyper and, to evalutate the potential diagnostic role of CFDS in mild thyroid disease in absence of a significant alteration in the serum level of circulating thyroid hormones.

In this study, patients with SHyper (the case group) and euthyroid patients (the control group) were enrolled. All patients from the two groups who were affected by multinodular goiter as preoperative diagnosis, underwent total thyroidectomy. In both groups preoperative examination included a conventional grey-scale sonography, followed by CFDS. Quantitative flow evaluation was performed measuring the maximal peak systolic velocity (PSV) at the level of intrathyroid arteries and inferior thyroid artery.

Patients with SHyper showed an increased thyroid vascularization both intranodular and peripheral and the mean PSV values were higher in case patients than in control subjects.

We have shown that significant changes in thyroid vascularity and blood flow velocity are already present in patients with SHyper. CFDS is a suitable technique to identify SHyper.