Touati G, Léger J, Toublanc J E, Farriaux J P, Stuckens C, Ponte C, David M, Rochiccioli P, Porquet D, Czernichow P
Hôpital Saint-Vincent de Paul, Paris, France.
Eur J Pediatr. 1997 Feb;156(2):94-8. doi: 10.1007/s004310050562.
The adequate L-thyroxine dosage for the initial treatment of infants with congenital hypothyroidism is a subject of controversy. Some recommend higher dosages (> 10 micrograms/kg/day) to ensure adequate levels, while others advocate lower dosages to permit normalisation of thyroid status. The aim of this study was to evaluate the results of a treatment strategy using an initial dosage of 7.5-8.0 micrograms/kg per day, TSH measurements being taken at 15 and 30 days of treatment. Fifty one newborns infants with primary congenital hypothyroidism detected by neonatal screening were treated with the same therapeutic strategy. A mean L-thyroxine dosage of 7.9 micrograms/kg per day at the onset of treatment and 6.6 micrograms/kg/d at 2 months, normalised the FT4 and FT3 levels at 15 days in 100% and TSH levels at 2 months in 90% of cases. Many patients showed elevated levels of FT4 and a systematic higher initial dosage could expose many infants to a dangerous hyperthyroidism. Patients with abnormal TSH levels at 2 months already had higher TSH levels in the first 8 weeks of life and, despite higher L-thyroxine dosage, also exhibited lower FT4 and FT3 levels. These patients who needed an early increase in dosage had already shown a more profound ante and neonatal hypothyroidism. This subgroup of patients require a higher dosage of thyroxine and early assessment of FT4, FT3 and TSH levels are required for optimum dosage choice.
Even though a subgroup of patients may require a higher dosage of L-thyroxine, an initial dosage of 7.5-8.0 micrograms/kg per day, with an early assessment of FT4, FT3, and TSH levels, is adequate for the treatment of the majority of infants with congenital hypothyroidism.
先天性甲状腺功能减退症婴儿初始治疗时左甲状腺素的合适剂量存在争议。一些人推荐较高剂量（>10微克/千克/天）以确保达到足够水平，而另一些人则主张较低剂量以使甲状腺状态正常化。本研究的目的是评估采用每天7.5 - 8.0微克/千克的初始剂量的治疗策略的结果，在治疗第15天和第30天进行促甲状腺激素（TSH）测量。通过新生儿筛查发现的51例原发性先天性甲状腺功能减退症新生儿采用相同的治疗策略进行治疗。治疗开始时左甲状腺素的平均剂量为每天7.9微克/千克，2个月时为6.6微克/千克/天，100%的病例在第15天时游离甲状腺素（FT4）和游离三碘甲状腺原氨酸（FT3）水平正常化，90%的病例在2个月时促甲状腺激素（TSH）水平正常化。许多患者的FT4水平升高，系统性地采用更高的初始剂量可能会使许多婴儿面临危险的甲状腺功能亢进症。2个月时TSH水平异常的患者在生命的前8周TSH水平就已经较高，尽管左甲状腺素剂量较高，但FT4和FT3水平也较低。这些需要早期增加剂量的患者已经表现出更严重的产前和新生儿期甲状腺功能减退。这一亚组患者需要更高剂量的甲状腺素，并且为了选择最佳剂量需要早期评估FT4、FT3和TSH水平。
尽管有一亚组患者可能需要更高剂量的左甲状腺素，但每天7.5 - 8.0微克/千克的初始剂量，同时早期评估FT4、FT3和TSH水平，对于大多数先天性甲状腺功能减退症婴儿的治疗是足够的。
