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

Patients with autonomously functioning thyroid nodules (AFTN) may not have an abnormal TSH value, particularly in iodine-deficient areas.

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).

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.

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.

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.