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Dual thyroid ectopia prevalence higher than previously reported
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The prevalence of dual thyroid ectopia among babies with congenital hypothyroidism appears to be higher than previously reported, according to study findings.
Catherine Peters, MD, MBChB, MRCP, FRCPCH, a consultant in the department of endocrinology at the Great Ormond Street Hospital for Children in London, and colleagues evaluated data on 837,377 babies screening for congenital hypothyroidism who were referred through the U.K. Newborn Blood Spot Screening program between 2006 and 2012. Researchers sought to determine the incidence of dual ectopia in congenital hypothyroidism and compare the phenotype with single ectopia or thyroid agenesis.
Overall, 730 babies were referred for diagnostic confirmation; 134 diagnosed with thyroid ectopia and 73 with thyroid agenesis.
Of the patients with thyroid ectopia, 21 had dual foci, for an incidence of 2.5 per 100,000 births.
Compared with the single ectopia and agenesis groups, the dual ectopia group had lower thyroid-stimulating hormone on the screening blood spot (P < .001). The dual ectopia group had similar TSH and free thyroxine levels as the single ectopia group, whereas the levels were significantly different from the agenesis group (P < .001).
Among all patients with congenital hypothyroidism, a negative association was found between serum free T4 and TSH (P < .001).
“In this large study of babies with [congenital hypothyroidism], we report a higher incidence of dual ectopia than previously reported,” the researchers wrote. “The strength of the study is inclusion of all babies born in the region with [congenital hypothyroidism]. Screening biochemistry would initially suggest a milder deficiency of [T4] as blood spot TSH concentration was lower in the dual ectopia group. Altered feedback would not explain this difference as the relationship between serum TSH and [free T4] concentrations (albeit at a later time point) were similar between the two ectopia groups. Our data suggest that the poorly functioning ectopic thyroid at diagnosis becomes less effective at thyroxine production over time.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
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