Initial treatment dose of L-thyroxine in congenital hypothyroidism

详细信息    查看全文

• 作者：Karin A. Selva ; Scott H. M ; el ; Leanne Rien ; David Sesser ; Richard Miyahira ; Michael Skeels ; Jerald C. Nelson ; Stephen H. LaFranchi
• 刊名：The Journal of Pediatrics
• 出版年：2002
• 出版时间：December 2002
• 年：2002
• 卷：141
• 期：6
• 页码：786-792
• 全文大小：108 K

文摘

Objectives: To determine the optimal initial treatment dose of L-thyroxine in congenital hypothyroidism (CH) by evaluating the time course of rise of thyroxine (T₄) and free T₄ concentrations into an established ȁc;target range” and normalization of thyroid-stimulating hormone (TSH) and to reevaluate the ȁc;target range” for T₄ and free T₄ concentrations during the first 2 weeks of CH treatment. Study design: Infants of birth weight 3 to 4 kg with CH (n = 47) detected by newborn screening were randomly assigned into three L-thyroxine treatment dose arms: 37.5 ;c;g/day (group 1); 62.5 ;c;g/day for 3 days, then 37.5 ;c;g/day (group 2); and 50 ;c;g/day (group 3). Serum T₄, free T₄, triiodothyronine (T₃), free T₃, and TSH were measured before treatment and at 3 days and 1, 2, 4, 8, and 12 weeks after treatment. Results: T₄ and free T₄ concentrations increased into the target range (10 to 16 ;c;g/dL) by 3 days of therapy in infants in groups 2 and 3 and by 1 week in group 1; 50 ;c;g/day (average 14.5 ;c;g/kg/day) provided the most rapid normalization of TSH by 2 weeks. With the use of linear regression analysis of T₄ versus TSH or free T₄ versus TSH plots, the intercept at the lower range of normal for TSH (1.7 mU/L) showed T₄ = 19.5 ;c;g/dL and free T₄ = 5.23 ng/dL. Conclusions: Initial dosing of 50 ;c;g/day (12-17 ;c;g/kg per day) raised serum T₄ and free T₄ concentrations to target range by 3 days and normalized TSH by 2 weeks of therapy. We recommend consideration of a somewhat higher ȁc;target range” of 10 to 18 ;c;g/dL for T₄ and 2 to 5.0 ng/dL for free T₄ during the first 2 weeks of L-thyroxine treatment. After 2 weeks of treatment, the target range drops to 10 to 16 ;c;g/dL for T₄ and 1.6 to 2.2 for free T₄. (J Pediatr 2002;141:786-92)