BACKGROUND We estimated the incidence of CH in twins, analyse the clinical features of CH cases in twins and further evaluate the CH screening strategy and recall procedures for twins. METHODS A retrospective investigation of the screening results and confirmed cases in 724,791 newborns was conducted from 2015 to 2017 in Guangzhou. Clinical features were compared between twins with CH and singletons with CH. In addition, the twins were further divided into same-sex twins and different-sex twins to analyse the characteristics and incidence of CH and to compare differences in the confirmed cases in the 2 groups. RESULTS The incidence of CH in same-sex twins was 1/593, which was much higher than the incidence of CH in singletons (1/1323) and different-sex twins (1/3060). Of the 20 twins diagnosed with CH, 17 were same-sex twins and 3 were different-sex twins. Among the six pairs of same-sex twins with CH, four had TSH inconsistency, which reached 67%. Eight of the 17 cases of same-sex twins diagnosed with CH had negative results at the first screening. CONCLUSIONS Distinguishing same-sex twins from different-sex twins during newborn screening is more feasible. The incidence of CH in same-sex twins is much higher than that in the general population and the risk of transient CH is relatively high. In positive cases in same-sex twins, the simultaneous recall of the twin can effectively avoid a missed diagnosis. The screening center should properly evaluate the recall strategy and screening procedure for twins, especially twins of the same-sex.

中文翻译：

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同性双胞胎先天性甲状腺功能低下的发生率很高，而且在新生儿筛查时很容易被漏诊。

背景：我们估算了双胞胎中CH的发生率，分析了双胞胎中CH病例的临床特征，并进一步评估了双胞胎的CH筛查策略和召回程序。方法回顾性分析2015年至2017年在广州市共724791例新生儿的筛查结果和确诊病例。比较了有CH的双胞胎和有CH的单胎的临床特征。此外，将双胞胎进一步分为同性双胞胎和异性双胞胎，以分析CH的特征和发生率，并比较两组确诊病例的差异。结果同性双胞胎的CH发生率为1/593，远高于单身双胎（1/1323）和异性双胞胎（1/3060）的CH发生率。在被诊断出患有CH的20对双胞胎中，17是同性双胞胎，3是异性双胞胎。在六对有CH的同性双胞胎中，有四对具有TSH不一致，达到67％。在第一次筛查中，被诊断为CH的17例同性双胞胎中有8例结果阴性。结论在新生儿筛查中将同性双胞胎与异性双胞胎区分开是更可行的。同性双胞胎中CH的发生率远高于普通人群，短暂性CH的风险相对较高。在同性双胞胎的阳性病例中，双胞胎的同时召回可以有效地避免漏诊。筛查中心应适当评估双胞胎，尤其是同性双胞胎的召回策略和筛查程序。在第一次筛查中，被诊断为CH的17例同性双胞胎中有8例结果阴性。结论在新生儿筛查中将同性双胞胎与异性双胞胎区分开是更可行的。同性双胞胎中CH的发生率远高于普通人群，短暂性CH的风险相对较高。在同性双胞胎的阳性病例中，双胞胎的同时召回可以有效地避免漏诊。筛查中心应适当评估双胞胎，尤其是同性双胞胎的召回策略和筛查程序。在第一次筛查中，被诊断为CH的17例同性双胞胎中有8例结果阴性。结论在新生儿筛查中将同性双胞胎与异性双胞胎区分开是更可行的。同性双胞胎中CH的发生率远高于普通人群，短暂性CH的风险相对较高。在同性双胞胎的阳性病例中，双胞胎的同时召回可以有效地避免漏诊。筛查中心应适当评估双胞胎，尤其是同性双胞胎的召回策略和筛查程序。同性双胞胎中CH的发生率远高于普通人群，短暂性CH的风险相对较高。在同性双胞胎的阳性病例中，双胞胎的同时召回可以有效地避免漏诊。筛查中心应适当评估双胞胎，尤其是同性双胞胎的召回策略和筛查程序。同性双胞胎中CH的发生率远高于普通人群，短暂性CH的风险相对较高。在同性双胞胎的阳性病例中，双胞胎的同时召回可以有效地避免漏诊。筛查中心应适当评估双胞胎，尤其是同性双胞胎的召回策略和筛查程序。