The effect of anti-thyroid drug treatment duration on thyroid gland microvessel density and intraoperative blood loss in patients with Graves' disease.

Background: Preoperative preparation of the patient with Graves' disease (GD) is crucial to avoid intraoperative or postoperative complications associated with anesthesia or surgery. We aimed to evaluate thyroid blood flow and microvessel density in patients with GD according to antithyroid drug (ATD) treatment, preoperatively.

Method: Forty-three patients were divided into two groups according to the ATD type. Patients in group 1 (n = 25) were treated with methimazole, whereas patients in group 2 (n = 18) were treated with propylthiouracil, preoperatively. Blood flow through the thyroid arteries was measured by color flow Doppler ultrasonography. The microvessel density (MVD) was assessed immunohistochemically and via Western blot analysis using the level of CD-34expression in thyroid tissue.

Results: There was a positive correlation between blood loss and thyroid volume (r(s) = 0.953, P = .0001) and blood flow (r(s) = 0.720, P = .0001) and CD-34 expression (r(s) = 0.331, P = .03) and MVD (r(s) = 0.442, P = .003). No correlation was observed between ATD type and thyroid vascularity. In patients with longer treatment duration before operation, thyroid vascularity was significantly lower relative to patients with shorter treatment durations. According to logistic regression analysis, longer treatment duration had a 142-fold decreased rate of intraoperative blood loss independent of ATD type.

Conclusion: Preoperative ATD treatment duration may predict intraoperative blood loss during thyroidectomy. Longer treatment duration might be useful in reducing intraoperative bleeding, allowing better visualization and preservation of the nerves and parathyroid glands.