Clinical and epidemiological characteristics of thyroid hemiagenesis: ultrasound screening in patients with thyroid disease and normal population

Abstract

Thyroid hemiagenesis is a rare form of thyroid dysgenesis, in which one thyroid lobe fails to develop. The true prevalence of this rare abnormality is about 0.05-0.2% in normal population. We aimed to determine prevalence of thyroid hemiagenesis in patients with various thyroid disorders and a normal population in a mild to moderate iodine-deficient area. The clinical and thyroid ultrasonography records of 4,833 patients who presented with various thyroid disorders were reviewed. In addition, ultrasonographic data of two large surveys carried out for the community screening of iodine status of children (n = 4,772) and thyroid disorders of adult subjects (n = 2,935) were analyzed. In patients with thyroid disorders, we found 12 cases with thyroid hemiagenesis (0.25%). Thyroid hemiagenesis was due to the agenesis of the left lobe in all cases. The underlying thyroid diseases were Hashimoto's thyroiditis (n = 4), euthyroid multinodular goiter (n = 4), and toxic adenoma (n = 1). Three subjects have no underlying thyroid disease. In ultrasonography screening of normal population, altogether, the absence of the left lobe was detected in only two cases, indicating a true prevalence of thyroid hemiagenesis of 0.025%. None of the reviewed patients had thyroid dysfunction. Our community-based data is in accordance with previous studies in terms of prevalence and male-to-female ratio.

Increased risk of thyroid pathology in patients with thyroid hemiagenesis: results of a large cohort case–control study

“…The fact that diagnosis of THA is often made when some other thyroid disease is present, coupled with the paucity of cases without overt thyroid disorder under observation, makes assessment of the outcome of patients affected with this anomaly very difficult. However, the latest analysis of Gursoy et al revealed that the incidence of THA among patients with thyroid disorders is tenfold greater than in the healthy population, supporting our conclusion that subjects with THA are more prone to develop thyroid disorders (16).…”

“…The only concomitant thyroid abnormalities described in this largely pediatric cohort were nodules and cysts, while immunological tests were not performed (19). The latest study of 14 subjects by Gursoy et al revealed the presence of associated thyroid pathology in nine patients, of whom four patients were diagnosed with Hashimoto's thyroiditis, four patients with a nontoxic multinodular goiter, and one patient with toxic adenoma (16). The observed variety of thyroid pathological entities overlapping THA suggests a strong impact of environmental factors, age structure, and the selection of the analyzed group on the clinical profile of patients with THA.…”

“…Recent population-based studies estimated the prevalence of THA for 0.2-0.025% (2,6,15,16). Agenesis, for unknown reasons, concerns the left thyroid lobe in the majority of cases, 68-80% according to different reports.…”

Agenesis of the thyroid isthmus

“…al, (7) it is a complete and congenital absence of the thyroid isthmus.In studies the prevalence of the thyroid hemiagenesis ranged between 00.5-0.2%. Most commonly seen in women and as left lobe agenesis (8)(9)(10) The thyroid isthmus agenesis is uncommon and we recognized the absence of isthmus incidentally during surgery. Operations memories are presented in figure 2 and figure 3.…”

“…Thyroid isthmus agenesis is not a situation where surgeons often encounter. When USG looked carefully, isthmus agenesis can be seen and this can help in surgery (8).…”