Prevalence, clinical, biochemical and sonographic characteristics of thyroid incidentaloma in Isfahan in 2006

Thyroid nodule which is not detected by palpation but is diagnosed following a radiological procedure or during surgery is called thyroid incidentaloma. This study was designed to investigate prevalence of sonographic thyroid incidentaloma in Isfahan in 2006. In this cross-sectional study, 2523 adults were randomly selected through cluster sampling method. 2045 of them had normal thyroid examination results; 234 of these were randomly selected for thyroid sonography. Their thyroid stimulating hormone (TSH) and urinary iodine concentrations (UIC) were measured. Prevalence of thyroid incidentaloma was 13.2%. Age of people with and without incidentaloma was 46.1±12.4 and 38.4±12.1 respectively (P=0.002). The prevalence was higher in females than males (19% vs. 10%, P=0.002). Labor frequency in women with thyroid incidentaloma was higher than that of the healthy group (93.7% vs 58.8%, P=0.001). Levels of TSH were not different in the two groups. Median UIC in incidentaloma group (14 µg/dL: 2-40) was significantly lower than that in the healthy group (20 µg/dL: 1.8-42), (P=0.02). Mean diameter of nodules was 8.14±3.43 mm. Prevalence of thyroid incidentaloma was 13.2% in Isfahan. This is similar to obtained results in other communities. The disorder was higher in females than in males and increased with age.