Corbetta Carlo, Weber Giovanna, Cortinovis Francesca, Calebiro Davide, Passoni Arianna, Vigone Maria C, Beck-Peccoz Paolo, Chiumello Giuseppe, Persani Luca
Laboratory for Neonatal Screening, Buzzi Children Hospital, Milan, Italy.
Clin Endocrinol (Oxf). 2009 Nov;71(5):739-45. doi: 10.1111/j.1365-2265.2009.03568.x. Epub 2009 Mar 28.
The guidelines of the National Academy of Clinical Biochemistry advocated the use of low bloodspot TSH (b-TSH) threshold for newborn screening of congenital hypothyroidism (CH). The impact generated by the application of this indication is largely unknown.
To determine the impact on CH epidemiology and classification generated by the introduction of low b-TSH cutoff.
Retrospective study of 629,042 newborns screened with b-TSH cutoffs of 12 (years 1999-2002) or 10 mU/l (2003-2005).
Congenital hypothyroidism incidence and classification. Results were compared with those virtually obtained with the previous cutoff (20 mU/l). Clinical re-evaluation after L-T4 withdrawal of a representative group of 140 CH children at 3-5 years.
Low b-TSH cutoffs allowed the detection of 435 newborns with confirmed CH (incidence 1:1446). Forty-five percent of CH infants, including 12/141 dysgenesis, would have been missed using the 20 mU/l cutoff. In contrast to current classification, 32% CH newborns had thyroid dysgenesis and 68% had a gland in situ (GIS). Premature birth was present in 20% of cases being associated with a 3-5 fold increased risk of GIS CH. Re-evaluation at 3-5 years showed a permanent thyroid dysfunction in 78% of 59 CH toddlers with GIS.
The use of low b-TSH cutoff allowed the detection of an unsuspected number of children with neonatal hypothyroidism, evolving in mild permanent thyroid dysfunction later in life. The incidence of CH in this Italian population appears to be double than previously thought with a clear-cut prevalence of functional defects over dysgenetic ones.
美国国家临床生物化学学会的指南提倡采用低血斑促甲状腺激素（b-TSH）阈值进行先天性甲状腺功能减退症（CH）的新生儿筛查。应用该指标所产生的影响在很大程度上尚不清楚。
确定引入低b-TSH临界值对CH流行病学及分类产生的影响。
对629,042例新生儿进行回顾性研究，这些新生儿的b-TSH临界值为12（1999 - 2002年）或10 mU/l（2003 - 2005年）。
先天性甲状腺功能减退症的发病率及分类。将结果与之前临界值（20 mU/l）实际获得的结果进行比较。对140例3 - 5岁的CH儿童代表组在停用左甲状腺素（L-T4）后进行临床重新评估。
低b-TSH临界值使得检测出435例确诊为CH的新生儿（发病率1:1446）。若采用20 mU/l的临界值，45%的CH婴儿，包括12/141例甲状腺发育不全患儿将会漏诊。与当前分类不同的是，32%的CH新生儿存在甲状腺发育不全，68%的患儿甲状腺位于原位（GIS）。20%的病例为早产，与GIS-CH风险增加3 - 5倍相关。3 - 5岁时的重新评估显示，59例GIS-CH幼儿中有78%存在永久性甲状腺功能障碍。
采用低b-TSH临界值能够检测出数量意外的新生儿甲状腺功能减退症患儿，这些患儿在生命后期会发展为轻度永久性甲状腺功能障碍。在这个意大利人群中，CH的发病率似乎是之前认为的两倍，功能性缺陷明显多于发育异常性缺陷。
