Department of Paediatric Endocrinology, Children's Health Ireland at Temple St, Dublin, Ireland.
Department of Paediatrics, School of Medicine, University College, Dublin, Ireland.
Horm Res Paediatr. 2021;94(1-2):36-43. doi: 10.1159/000514989. Epub 2021 May 27.
Scintigraphy using technetium-99m (99mTc) is the gold standard for imaging the thyroid gland in infants with congenital hypothyroidism (CHT) and is the most reliable method of diagnosing an ectopic thyroid gland. One of the limitations of scintigraphy is the possibility that no uptake is detected despite the presence of thyroid tissue, leading to the spurious diagnosis of athyreosis. Thyroid ultrasound is a useful adjunct to detect thyroid tissue in the absence of 99mTc uptake.
We aimed to describe the incidence of sonographically detectable in situ thyroid glands in infants scintigraphically diagnosed with athyreosis using 99mTc and to describe the clinical characteristics and natural history in these infants.
The newborn screening records of all infants diagnosed with CHT between 2007 and 2016 were reviewed. Those diagnosed with CHT and athyreosis confirmed on scintigraphy were invited to attend a thyroid ultrasound.
Of the 488 infants diagnosed with CHT during the study period, 18/73 (24.6%) infants with absent uptake on scintigraphy had thyroid tissue visualised on ultrasound (3 hypoplastic thyroid glands and 15 eutopic glands). The median serum thyroid-stimulating hormone (TSH) concentration at diagnosis was significantly lower than that in infants with confirmed athyreosis (no gland on ultrasound and no uptake on scintigraphy) (74 vs. 270 mU/L), and median free T4 concentration at diagnosis was higher (11.9 vs. 3.9 pmol/L). Six of 10 (60%) infants with no uptake on scintigraphy but a eutopic gland on ultrasound had transient CHT.
Absent uptake on scintigraphy in infants with CHT does not rule out a eutopic gland, especially in infants with less elevated TSH concentrations. Clinically, adding thyroid ultrasound to the diagnostic evaluation of infants who have athyreosis on scintigraphy may avoid committing some infants with presumed athyreosis to lifelong levothyroxine treatment.
描述使用 99mTc 诊断为无甲状腺扫描的甲状腺功能减退症婴儿中超声可检测到原位甲状腺的发生率，并描述这些婴儿的临床特征和自然病史。
回顾了 2007 年至 2016 年间所有诊断为先天性甲状腺功能减退症的婴儿的新生儿筛查记录。对经放射性核素扫描诊断为先天性甲状腺功能减退症和无甲状腺扫描的婴儿进行甲状腺超声检查。
在研究期间，488 例诊断为先天性甲状腺功能减退症的婴儿中，18/73（24.6%）例放射性核素扫描未见摄取的婴儿在超声下可见甲状腺组织（3 例甲状腺发育不良，15 例甲状腺位置正常）。诊断时血清促甲状腺激素（TSH）浓度中位数明显低于经超声证实无甲状腺和无摄取的婴儿（74 vs. 270 mU/L），游离 T4 浓度中位数较高（11.9 vs. 3.9 pmol/L）。10 例无摄取但超声下为正常甲状腺的婴儿中，有 6 例（60%）为一过性先天性甲状腺功能减退症。
在先天性甲状腺功能减退症婴儿中，放射性核素扫描无摄取并不能排除正常甲状腺的存在，尤其是在 TSH 浓度升高不明显的婴儿中。临床上，对放射性核素扫描诊断为无甲状腺的婴儿进行甲状腺超声检查，可能有助于避免一些被认为无甲状腺的婴儿接受终身左旋甲状腺素治疗。
