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

OBJECTIVE
Thyroid hemiagenesis (THA) is an anomaly resulting from the developmental failure of one thyroid lobe. Etiopathogenesis, clinical significance, and management of patients in whom THA is diagnosed are still a matter of debate. The aim of the study is to provide the first systematic analysis of a large cohort of subjects with THA.


DESIGN
Forty patients with THA are described in comparison to a control group of 80 subjects with fully developed thyroid gland.


METHODS
Serum concentrations of thyrotropin (TSH), free thyroxine (FT(4)), free triiodothyronine (FT(3)), and thyroid autoantibodies were measured. In 37 patients, thyroid ultrasonography and Tc-99m thyroid scintiscan were performed, followed by fine-needle aspiration biopsy if indicated. The remaining archival three cases were diagnosed with the use of I-131 scintiscan under basal conditions and after TSH stimulation.


RESULTS
Patients with THA, while usually clinically euthyroid, presented with significantly higher levels of TSH and FT(3) as well as with higher FT(3)/FT(4) concentration in comparison to the control group. Furthermore, a higher incidence of associated functional, morphological, and autoimmune thyroid disorders in patients with THA was observed when compared to subjects with bilobate thyroid (P<0.05).


CONCLUSIONS
Our results revealed that individuals with THA are more likely to develop thyroid pathology. The observed high incidence of associated pathologies is presumably due to long-lasting TSH overstimulation. Therefore, THA diagnosis should be followed by systematic observation and adequate levothyroxine treatment in patients with elevated TSH level.