Coexistence of resistance to thyroid hormone and ectopic thyroid: ten-year follow-up

Abstract

SUMMARYResistance to thyroid hormone (RTH) coexisting with ectopic thyroid is rare. Here we report a case of RTH with ectopic thyroid. A ten-year-old girl had been misdiagnosed as congenital hypothyroidism and treated with levothyroxine since she was born. Ten-year follow-up showed that the elevated thyrotropin was never suppressed by levothyroxine and no signs indicating hyperthyroidism or hypothyroidism despite elevated FT3 and FT4 levels. Therefore the girl developed no defects in physical and cognitive development. Pituitary adenoma was excluded by magnetic resonance imaging. Ultrasonography did not find the thyroid gland in the normal place, while the thyroid scan found a large lingual thyroid gland. The octreotide inhibition test showed a reduction in thyrotropin by 41.98%. No mutation was detected in the thyroid hormone receptor (THR) β, THRα, thyrotropin receptor (TSHR), and GNAS1 genes. To our knowledge, it is an interesting RTH case coexisting with lingual thyroid. Arch Endocrinol Metab. 2016;60(6):601-4

Resistance to Thyroid Hormone Beta: A Focused Review

“…Children with RTHb commonly have short stature, goiter and learning difficulties (14) and in association with CH will present high serum TSH and may exhibit hypothyroid symptoms when treated with standard levothyroxine doses. Five reports of RTHb with CH due to ectopic thyroid tissue have been reported (18)(19)(20)(21)(22). Of note, the case reported by Guo et al, had a lingual thyroid with a typical RTHb phenotype but no detectable mutations in the THRB gene (21).…”

“…Five reports of RTHb with CH due to ectopic thyroid tissue have been reported (18)(19)(20)(21)(22). Of note, the case reported by Guo et al, had a lingual thyroid with a typical RTHb phenotype but no detectable mutations in the THRB gene (21).…”

Update on resistance to thyroid hormone syndromeβ

“…Guoetal [26]reported a case of rare RTH-β with an ectopic thyroid gland in which a 10-year-old girl was diagnosed with congenital hypothyroidism, treated with L-T4. Her TSH was not suppressed, and FT3 and FT4 levels were elevated after 10 years of follow-up without any symptoms of hypothyroidism and hyperthyroidism.…”

Tissue sensitivity to thyroid hormones may change over time

“…The reasons for this condition are unknown, but a genetic origin appears unlikely, as it has been observed either in patients with ectopic or eutopic thyroid gland [1]. The concomitant occurrence of CH and resistance to thyroid hormone syndrome type  (RTH) is exceptional, since only five patients have been described so far, and only in 4 a mutation in the RTHß gene have been demonstrated [4,5,6,7]. RTH, firstly described by Refetoff in 1967 [8], is characterized by elevated circulating fT4 and fT3 together with an unsuppressed TSH.…”

“…Table1BClinical and biochemical of the patients included in the study when RETH was discovered Results of the l-T3 suppression test in patient 1 (Free TH values in cobas are reported in bold and those in delfia in italics) Normal values: TSH (0.5-3.6), fT4 (12-22) (9-20), fT3 (3.5-7.7)(4)(5)(6)(7)(8) …”