Background: There are no open population epidemiological studies to determine the true prevalence of thyroid nodules in the Valley of Mexico. The aim of this investigation was to determine prevalence.
Methods: We carried out a cross-sectional, observational, descriptive study in 2401 open population subjects in the Valley of Mexico. All subjects were at least 18 years of age with no clinical history of thyroid disease. Variables analyzed were age, gender, thyroid nodule identified by neck palpation or neck ultrasound, TSH levels, cytological diagnosis and histopathological diagnosis in case of clinical thyroid nodule detection. Percentages as a summary measure for qualitative variables and proportions and chi-square for independent variables were used for statistical analysis.
Results: Included were 2401 subjects with a mean age of 39 years (82.4% female, 17.6% male). Thirty-four (1.4%) thyroid nodules were detected by palpation and 471 (19.6%) by ultrasound. The 34 palpable thyroid nodules corresponded to 16 (47.2%) colloid goiters, 8 (23.5%) follicular adenomas, 7 (20.5%) Hashimoto's thyroiditis, 2 (5.9%) papillary carcinomas and 1 (2.9%) oxiphilic cell adenoma. Nonpalpable thyroid nodules detected by ultrasound did not develop illness at 2-year follow-up. TSH was normal in 1620 (67.4%), high in 515 (21.5%) and low in 266 (11.1%) patients. There was no relationship between TSH levels and final diagnosis of the 34 palpable nodules (p >0.05).
Conclusions: Prevalence of palpable thyroid nodule in the Valley of Mexico is 1.4%; 5.9% of these are due to papillary thyroid cancer. TSH levels do not correlate with the presence or cause of the thyroid nodule.