TY - JOUR
T1 - Initial treatment dose of L-thyroxine in congenital hypothyroidism
AU - Selva, Karin A.
AU - Mandel, Scott H.
AU - Rien, Leanne
AU - Sesser, David
AU - Miyahira, Richard
AU - Skeels, Michael
AU - Nelson, Jerald C.
AU - LaFranchi, Stephen H.
PY - 2002/12/1
Y1 - 2002/12/1
N2 - Objectives: To determine the optimal initial treatment dose of L-thyroxine in congenital hypothyroidism (CH) by evaluating the rime course of rise of thyroxine (T4) and free T4 concentrations into an established "target range" and normalization of thyroid-stimulating hormone (TSH) and to reevaluate the "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 μg/day (group 1); 62.5 μg/day for 3 days, then 37.5 μg/day (group 2); and 50 μg/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 μg/dL) by 3 days of therapy in infants in groups 2 and 3 and by 1 week in group 1; 50 μg/day (average 14.5 μg/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 μg/dL and free T4 = 5.23 ng/dL. Conclusions: Initial dosing of 50 μg/day (12-17 μg/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 "target range" of 10 to 18 μg/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 μg/dL for T4 and 1.6 to 2.2 for free T4.
AB - Objectives: To determine the optimal initial treatment dose of L-thyroxine in congenital hypothyroidism (CH) by evaluating the rime course of rise of thyroxine (T4) and free T4 concentrations into an established "target range" and normalization of thyroid-stimulating hormone (TSH) and to reevaluate the "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 μg/day (group 1); 62.5 μg/day for 3 days, then 37.5 μg/day (group 2); and 50 μg/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 μg/dL) by 3 days of therapy in infants in groups 2 and 3 and by 1 week in group 1; 50 μg/day (average 14.5 μg/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 μg/dL and free T4 = 5.23 ng/dL. Conclusions: Initial dosing of 50 μg/day (12-17 μg/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 "target range" of 10 to 18 μg/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 μg/dL for T4 and 1.6 to 2.2 for free T4.
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U2 - 10.1067/mpd.2002.128887
DO - 10.1067/mpd.2002.128887
M3 - Article
C2 - 12461494
AN - SCOPUS:0036916572
SN - 0022-3476
VL - 141
SP - 786
EP - 792
JO - Journal of Pediatrics
JF - Journal of Pediatrics
IS - 6
ER -