Dynamics of the plasma concentrations of TSH, FT4 and T3 following thyroxine supplementation in congenital hypothyroidism
Dynamics of the plasma concentrations of TSH, FT4 and T3 following thyroxine supplementation in congenital hypothyroidism
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DOI：
10.1046/j.1365-2265.2002.01632.x
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发表时间：
2002-10-01
影响因子：
3.2
通讯作者：
Vulsma, T
中科院分区：
文献类型：
--
作者：
Bakker, B;Kempers, MJE;Vulsma, T
目的分析先天性甲状腺功能减退症（CH）儿童开始补充T4后甲状腺功能的各种诊断决定因素的血浆浓度动态。在甲状腺素治疗的第一阶段，TSH和游离T4（FT 4）的生化动力学的描述对于描述T4的初始剂量和具有可变形式CH的新生儿的剂量调整的实际轮廓是重要的。设计对频繁的血浆TSH、总T4（T4）、在治疗的第一周期间，对30名CH新生儿进行FT 4和总T3（T3）测量，初始每日T4剂量范围为4.8 - 11.1 μ g/kg。结果治疗3-4天后，初始血浆TSH浓度降低50%，与CH严重程度无关。在开始补充T4后的中位数32天，血浆TSH范围为0.4 - 4.0 mU/l。FT 4达到年龄相关正常值（12-29 pmol/l）所需的平均时间间隔为3天。血浆T3浓度的增加在几天内趋于平稳，当T4浓度达到100 nmol/L左右。结论血浆T3和FT 4浓度在甲状腺素治疗开始后几天达到正常范围。相比之下，血浆TSH浓度正常化需要几周时间。在血浆TSH正常化时，CH新生儿的血浆FT 4浓度范围高于正常范围。当TSH正常化是CH治疗的目标时，治疗前几个月的血浆FT 4目标范围需要调整。治疗第一个月期间，血浆TSH浓度无助于评估适当的T4补充剂量。一旦血浆TSH达到正常值，它就成为除血浆FT 4之外的一个可靠的决定因素。
OBJECTIVE The dynamics of the plasma concentrations of various diagnostic determinants of thyroid function were analysed in children with congenital hypothyroidism (CH) after the start of T4 supplementation. The description of the biochemical dynamics of TSH and free T4 (FT4) during the first period of thyroxine treatment is important to depict the practical outlines of the initial dosage of T4 and dosage adjustments for newborns with variable forms of CH.DESIGN A retrospective analysis was performed of frequent plasma TSH, total T4 (T4), FT4 and total T3 (T3) measurements in 30 CH neonates during the first weeks of treatment, treated with initial daily T4 dosages ranging from 4.8 to 11.1 mug/kg.RESULTS A 50% reduction in the initial plasma TSH concentration was achieved after 3-4 days of treatment, independent of CH severity. At a median of 32 days after the start of T4 supplementation, plasma TSH ranged between 0.4 and 4.0 mU/l. The mean interval needed for FT4 to reach the age-related normal values (12-29 pmol/l) was 3 days. The increase in plasma T3 concentrations levelled off within a few days, when T4 reached concentrations of around 100 nmol/l.CONCLUSIONS Plasma T3 and FT4 concentrations reach the normal range a few days after thyroxine treatment is started. By contrast, normalization of plasma TSH concentration takes several weeks. At the time that plasma TSH is normalized, CH neonates show a higher range of plasma FT4 concentrations than the normal range. When TSH normalization is the goal of treatment in CH, the target range for plasma FT4 during treatment in the first months needs to be adapted.During the first month of treatment the plasma TSH concentration is not helpful in assessing the proper T4 supplementation dosage. Once plasma TSH has reached normal values, it becomes a reliable determinant in addition to plasma FT4.