Thyroid volume was measured by ultrasonography in 80 euthyroid patients with sporadic nontoxic goitre and in 50 healthy adults, all residing in non-iodine deficient areas. All patients were referred because of complaints of goitre and had been diagnosed as cases of goitre by inspection and palpation. The thyroid volume in 15 patients with goitre (19%) was within the normal reference range (4.9-19.1 ml). Fourteen of the 15 patients had thyroid nodules larger (mean diameter 2.9 +/- 1.1 cm) than those detected in nine of the healthy adults (mean diameter 0.8 +/- 0.6 cm; P less than 0.001). Thyroid size as estimated by inspection and palpation (grade OA to III according to Stanbury et al., 1974) was poorly related to thyroid volume measured by ultrasonography.
In conclusion: (1) a thyroid volume within the normal reference range does not rule out the presence of nodular goitre; and (2) application of thyroid volume measurement by ultrasonography may prevent overestimation of goitre prevalence in epidemiological surveys.