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 AFTN 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: Group 1 (no.=25) with TSH>0.35 IU/l, and Group 2 (no.=53) 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 Group 2 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 peri-intranodular 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.