初始小剂量L-甲状腺素治疗先天性甲状腺功能低下症疗效研究

目的:探讨左旋甲状腺素替代治疗先天性甲状腺功能低下症(CH)的最适剂量.方法:138例CH患儿按总T3(TT3)、总T4(TT4)和TSH的水平分为亚临床型、轻型和重型三组,各组分别给予(3.5±1.0)μg/(kg.d)、(4.3±0.7)μg/(kg.d)、(4.7±0.6)μg/(kg.d)剂量的左旋甲状腺素片,并于1、2、3个月复测血清TT3、TT4和TSH浓度,结合临床表现及时调整剂量;治疗至2岁左右测试发育商.结果:138例患儿左旋甲状腺素起始平均剂量为(4.3±0.9)μg/(kg.d).治疗1个月后各组患儿的平均TT3和TT4水平达正常范围;2个月后TT3和TT4水平达正常范围的上 1/2,临床无甲状腺功能低下的表现,但此时仍有32.6%的患儿TSH水平高于正常范围.治疗后各组临床和生化指标达正常的时间无差异(P＝0.925),三组间的起始剂量有显著性差异(P<0.01);各组间3个月内的平均用药剂量亦有显著性差异(P<0.01).18例患儿治疗至2岁,智力测试平均发育商为116.7±17.0.结论:治疗CH的起始用药剂量以(4.3±0.9)μg/(kg.d)为宜;CH的治疗最好根据临床症状和生化指标及时调整药量,做到剂量个体化.

Low initial dose of levothyroxine for treatment of congenital hypothyroidism

OBJECTIVE: To evaluate the results of treatment of infants with congenital hypothyroidism (CH) with a low initial dosage of levothyroxine. METHODS: 138 newborns with primary CH detected by neonatal screening were divided into 3 groups according to levels of serum TSH, TT(3) and TT(4): sub-clinical CH (TSH >50 mU/L), mild CH (TT(4) <54 nmol/L), severe CH (TT(4)<54 nmol/L and TT(3)<1.2 nmol/L). The initial dose of levothyroxine was (3.5 +/-1.0) microg/(kg.d) for sub-clinical CH group, (4.3 +/-0.7)microg/(kg.d) for mild CH group and (4.7 +/- 0.6)microg/(kg.d) for severe CH group. Follow-up evaluation was carried out at 1, 2 and 3 months of age by measuring serum levels of TT(3), TT(4) and TSH. The time, when clinical signs and symptoms were eliminated and serum levels of TT(3), TT(4) and TSH normalized, was recorded. Development Quotient (DQ) testing was performed when CH cases were about 2 years old. RESULTS: The mean initial dose of levothyroxine in 138 cases was (4.3 +/-0.9)microg/(kg.d). In one month the serum TT(3) and TT(4) levels returned to normal, while for TSH levels 67.4 % cases reached normal range in 2 months and 84.1 % in 3 months. Two months after therapy, the levels of TT(3) and TT(4) reached to the upper half of normal range and there were no signs or symptoms of hypothyroidism. The time for all cases in 3 groups to reach the normal clinical and biochemical indicators was similar (P=0.925). The dosage for cases with low circulating thyroxine before treatment was higher than that of the other groups (P<0.01). The average DQ score of 18 cases after treatment was 116.7 +/- 17.0. CONCLUSION: he levothyroxine dosage of (4.3 +/- 0.9)microg/(kg.d) is appropriate for the initial treatment of the majority of infants with CH. However it is better to individualize the dosage for each case.