title: Thyroid hemiagenesis: prevalence in normal children and effect on thyroid function.
abstract: Thyroid hemiagenesis prevalence was studied by neck ultrasound examination in 24,032 unselected 11- to 14-yr-old schoolchildren from southeastern Sicily. Twelve cases of thyroid hemiagenesis were identified, with a prevalence of 0.05%. The female to male ratio was 1:1.4. Thyroid hemiagenesis was always due to the absence (11 cases) or severe hypoplasia (1 case) of the left lobe. The hemiagenetic thyroid volume was within the normal total thyroid volume range normalized to age in 4 of 12 cases, enlarged in 3, and significantly reduced in 5. Thyroid function (thyroid hormones and TSH, both basal and 30 min after administration of 200 micro g TRH, iv) was evaluated in 9 of 12 children and was always within the normal range. However, children with thyroid hemiagenesis had an average serum TSH significantly higher than that of 18 matched controls (2.8 +/- 0.6 vs. 1.9 +/- 0.5 mU/liter; P < 0.001). This study confirms that thyroid hemiagenesis is nearly always due to left lobe defect, and that its prevalence is similar to the cumulative prevalence of thyroid agenesis and ectopia. Compensatory hypertrophy of the residual thyroid lobe occurs in most, but not all, cases and is due to thyroid tissue overstimulation by TSH. The high risk of goiter and hypothyroidism suggests systematic follow-up of all identified cases of thyroid hemiagenesis.
authors.affiliation: Endocrinologia, Dipartimento di Medicina Interna e Specialistica dell'Università di Catania, Ospedale Garibaldi, 95125 Catania, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Maiorana
authors.forename: Anna
authors.initials: A
authors.lastname: Carta
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Floriddia
authors.forename: Daniela
authors.initials: D
authors.lastname: Leonardi
authors.forename: Massimo
authors.initials: M
authors.lastname: Buscema
authors.forename: Lidia
authors.initials: L
authors.lastname: Sava
authors.forename: Francesca
authors.initials: F
authors.lastname: Calaciura
authors.forename: Riccardo
authors.initials: R
authors.lastname: Vigneri
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D006984:Hypertrophy; D008297:Male; D012802:Sicily / Q000453:epidemiology; D013961:Thyroid Gland / Q000002:abnormalities* / Q000473:pathology / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood; D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013974:Thyroxine