Thyroid scintigraphy: an old tool is still the gold standard for an effective diagnosis of autonomously functioning thyroid nodules

Background: Patients with autonomously functioning thyroid nodules (AFTN) may not have an abnormal TSH value, particularly in iodine deficient areas. Aim: to verify the accuracy of TSH as screening test in detecting AFTNs and to evaluate ultrasonographic features of thyroid nodules, which have resulted autonomously functioning at thyroid scintigraphy (TS). Methods: Seventy-eight patients with nodular goiter, no marker of autoimmunity and at least one AFTN at TS, were selected and divided in: Group1 (25 patients) with TSH >0.35 IU/L, and Group2 (53 patients) with TSH ≤0.35 IU/L. Results: In Group1 the mean nodule diameter was 19.8±9.4 mm; 12 nodules were isoechoic, 2 hyperechoic, and 11 hypoechoic. Vascular pattern was type I in 4, type II in 6 and type III in 15 nodules. In Group2 the mean nodule diameter was 28.6±14.2 mm; 27 nodules were isoechoic, 9 hyperechoic and 17 hypoechoic. Vascular pattern was type I in 14, type II in 15 and type III in 24 nodules. Conclusion: In our study TSH alone was not able to identify AFTN in 32% of the patients. All hot nodules predominantly showed an isoechoic pattern with periintranodular vascularization; however the presence of this pattern was not statistically significant. Moreover, we noticed a weak inverse correlation between the diameter of AFTN and TSH level. In conclusion TS is the most sensitive tool to detect AFTN, allowing a precocious diagnosis even in the presence of a normal TSH value.