Turkkahraman Doga, Alper Ozgul M, Aydin Funda, Yildiz Akin, Pehlivanoglu Suray, Luleci Guven, Akcurin Sema, Bircan Iffet
Department of Pediatrics, Division of Endocrinology, Akdeniz University Hospital, Antalya, Turkey.
J Pediatr Endocrinol Metab. 2009 Sep;22(9):845-51. doi: 10.1515/jpem.2009.22.9.845.
To determine the final diagnosis of patients with subclinical hypothyroidism (SCH), and to perform mutation screening of the thyroid peroxidase gene (TPO).
Infants with SCH without an identified etiology were included in the study. Patients with thyroid dysgenesis were excluded. Children > or = 2 years of age, and still on L-thyroxine (LT4) treatment underwent a diagnostic algorithm. After LT4 was discontinued for 4 weeks, thyroid function tests (TFT) were obtained. A perchlorate discharge test (PDT) was performed in patients with normal thyroid ultrasound but abnormal TFT. Sequence analysis of TPO was studied in all children who underwent a PDT.
Forty-eight patients (23 males and 25 females) completed the trial. Among these children, 19 (39.5%) had transient SCH, and 29 (60.5%) had permanent SCH. Among patients with permanent SCH, 19 had thyroid hypoplasia, six had partial iodide organification defect with positive PDT, and four had other dyshormonogenesis with negative PDT. Mean LT4 dose before the medication ceased was 1.2 +/- 0.5 microg/kg/day in transient cases, and 1.7 +/- 0.4 in those with permanent SCH (p < 0.05). No TPO mutation was detected. However, in five patients, seven different previously known TPO polymorphisms were detected: c.102C > G, L4L; > A, A576A; c.2088C > T, D666D; c.2263A > C, T725P; c.2630 T >C, V847A.
LT4 treatment should be stopped after the age of 2 years in infants with SCH without a definite pathology of the thyroid gland to exclude cases with transient hypothyroidism. Additionally, we should consider particularly thyroid gland hypoplasia, and also partial defects in iodide organification in infants with SCH.
确定亚临床甲状腺功能减退症（SCH）患者的最终诊断，并对甲状腺过氧化物酶基因（TPO）进行突变筛查。
本研究纳入病因未明的SCH婴儿。排除甲状腺发育异常的患者。对2岁及以上且仍在接受左甲状腺素（LT4）治疗的儿童进行诊断性评估。LT4停药4周后，进行甲状腺功能测试（TFT）。甲状腺超声正常但TFT异常的患者进行高氯酸盐释放试验（PDT）。对所有接受PDT的儿童进行TPO序列分析。
48例患者（23例男性和25例女性）完成试验。在这些儿童中，19例（39.5%）为暂时性SCH，29例（60.5%）为永久性SCH。在永久性SCH患者中，19例有甲状腺发育不全，6例有部分碘有机化缺陷且PDT阳性，4例有其他激素合成障碍且PDT阴性。暂时性病例停药前LT4平均剂量为1.2±0.5μg/kg/天，永久性SCH患者为1.7±0.4μg/kg/天（p<0.05）。未检测到TPO突变。然而，在5例患者中检测到7种不同的已知TPO多态性：c.102C>G，L4L；>A，A576A；c.2088C>T，D666D；c.2263A>C，T725P；c.2630T>C，V847A。
对于无明确甲状腺病变的SCH婴儿，2岁后应停止LT4治疗，以排除暂时性甲状腺功能减退症。此外，对于SCH婴儿，我们应特别考虑甲状腺发育不全，以及碘有机化的部分缺陷。
