Association of insulin-like growth factor-1 with thyroid nodules.

The aim of the present study was to investigate the relationship between insulin-like growth factor-1 (IGF-1) and thyroid nodules. A total of 56 patients with thyroid nodules confirmed by physical examination and ultrasound screening were randomly selected. The patients were divided into three groups by radionuclide scan: the hot nodule group (group 1, n=18); the cold and solid nodule group (group 2, n=18); and the cold and cystic nodule group (group 3, n=20). Cystic fluid samples from patients with cystic cold thyroid nodules were defined as group 4. A control group of 18 healthy adults matched for age, gender and body mass index (group 0) was also included. For all participants, levels of the thyroid hormones, TT3, TT4, TSH and IGF-1, were determined by radioimmunoassay. The measurement data were expressed as the mean ± standard deviation (SD). The analysis of variance was performed by the t-test and the correlation analysis was performed by linear regression. The serum levels of IGF-1 in the solid cold nodule group were significantly higher than those in the hot nodule group (P<0.05). Serum levels of IGF-1 in the cystic cold nodule group were significantly lower than those in the control group (P<0.05). The serum IGF-1 levels in the cystic fluid were significantly lower than those in the cystic cold nodule (P<0.05) and the control groups (P<0.05). Additionally, the mean serum IGF-1 level in patients with thyroid adenoma was significantly higher than that in the control group (P<0.05). The serum IGF-1 level may not be involved in the pathogenesis of hot thyroid nodules and cold and cystic thyroid nodules; however, it may play a significant role in the pathogenesis of certain solid cold thyroid nodules.