Endocrinology Service and Research Center, Sainte-Justine Hospital and Department of Pediatrics, University of Montreal, Montreal H3T 1C5, Canada.
J Clin Endocrinol Metab. 2011 Aug;96(8):2422-9. doi: 10.1210/jc.2011-1073. Epub 2011 Jun 1.
Congenital hypothyroidism (CH) is reportedly increasing in the United States, possibly reflecting changes in screening methods. In Québec, the same initial TSH cutoff (15 mU/liter) has been used for the last 20 yr, but in 2001, the cutoff was decreased from 15 to 5 mU/liter for the second test, which is requested when TSH is intermediate (15-30 mU/liter) on the first.
Our objective was to assess the incidence of CH over the last 20 yr in Québec.
DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURE: This is a population-based retrospective study. Incidences by etiology based on thyroid scintigraphy with technetium were compared between 1990-2000 and 2001-2009.
Of 1,660,857 newborns over 20 yr, 620 had CH (incidence 1:2679). Etiology was dysgenesis (n = 389, 1:4270), either ectopy (n = 290) or athyreosis (n = 99), goiter (n = 52, 1:31,940), normal-size gland in situ (n = 115, 1:14,442), and unknown (n = 64, 1:25,950). The new screening algorithm identified 49 additional cases (i.e. 25 normal-size gland in situ, 12 unknown etiology, 10 ectopies, and two goiters). Consequently, the incidence of normal-size gland in situ or of unknown etiology more than doubled (1:22,222 to 1:9,836, P = 0.0015; and 1:43,824 to 1:17,143, P = 0.0018, respectively) but that of dysgenesis and goiter remained stable. Had the 1990-2000 algorithm been applied in 2001-2009, no change in incidence would have been observed in any category.
Estimating the incidence of CH is influenced by minimal changes in TSH screening cutoffs. Lower cutoffs identify additional cases that have predominantly functional disorders whose impact on intellectual disability, if left untreated, remains to be determined.
据报道，先天性甲状腺功能减退症（CH）在美国的发病率正在上升，这可能反映了筛查方法的变化。在魁北克，过去 20 年来一直使用相同的初始 TSH 截止值（15mU/L），但在 2001 年，当 TSH 处于中间值（15-30mU/L）时，第二次测试的截止值从 15 降低到 5mU/L，第二次测试要求在第一次测试时 TSH 处于中间值（15-30mU/L）。
评估过去 20 年来魁北克 CH 的发病率。
设计、地点、患者和主要观察指标：这是一项基于人群的回顾性研究。根据锝甲状腺闪烁扫描确定病因的发病率，在 1990-2000 年和 2001-2009 年期间进行比较。
在过去 20 年的 1660857 名新生儿中，有 620 名患有 CH（发病率为 1：2679）。病因是发育不良（n=389，1：4270），包括异位（n=290）或无甲状腺（n=99）、甲状腺肿（n=52，1：31940）、原位正常大小腺体（n=115，1：14442）和未知（n=64，1：25950）。新的筛查算法确定了 49 例新病例（即 25 例原位正常大小腺体，12 例病因不明，10 例异位，2 例甲状腺肿）。因此，正常大小腺体或病因不明的发病率增加了一倍以上（1：22222 至 1：9836，P=0.0015；1：43824 至 1：17143，P=0.0018），而发育不良和甲状腺肿的发病率保持稳定。如果在 2001-2009 年应用 1990-2000 年的算法，则任何类别都不会观察到发病率的变化。
估计 CH 的发病率受到 TSH 筛查截止值的微小变化的影响。较低的截止值确定了更多的病例，这些病例主要是功能障碍，其对智力残疾的影响，如果不治疗，仍有待确定。
