Ultrasound Appearance of Thyroid Tissue in Hypothyroid Infants

Objective To identify those infants who need a higher starting dose of levothyroxine (l-T4) for early normalization of thyroid-stimulating hormone (TSH) level. Study design TSH levels at 2 time points (1 to 3 weeks and 3 to 5 weeks) after l-T4 therapy at a starting dose of 8 to12 μg/kg/day were eval...

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Bibliographic Details
Published in:The Journal of pediatrics 2008-07, Vol.153 (1), p.101-104
Main Authors: Ogawa, Eishin, MD, Kojima-Ishii, Kanako, MD, Fujiwara, Ikuma, MD
Format: Article
Language:English
Subjects:
Biological and medical sciences
Bone and Bones - metabolism
Congenital Hypothyroidism - diagnosis
Congenital Hypothyroidism - diagnostic imaging
Endocrinopathies
Female
General aspects
Humans
Infant, Newborn
Male
Medical sciences
Neonatal Screening - methods
Non tumoral diseases. Target tissue resistance. Benign neoplasms
Pediatrics
Pediatrics - methods
Retrospective Studies
Thyroid Function Tests - methods
Thyroid Gland - diagnostic imaging
Thyroid Gland - pathology
Thyroid. Thyroid axis (diseases)
Thyrotropin - blood
Thyroxine - therapeutic use
Ultrasonography - methods
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Summary:Objective To identify those infants who need a higher starting dose of levothyroxine (l-T4) for early normalization of thyroid-stimulating hormone (TSH) level. Study design TSH levels at 2 time points (1 to 3 weeks and 3 to 5 weeks) after l-T4 therapy at a starting dose of 8 to12 μg/kg/day were evaluated retrospectively in 22 hypothyroid infants screened for congenital hypothyroidism (CH) in terms of etiology as determined by ultrasonography (US), the size of distal femoral epiphysis (DFE), and initial thyroid function. Results The infants with a noneutopic thyroid or small DFE exhibited significantly higher posttherapeutic TSH levels compared with the other infants. Eight of the 9 infants who failed to achieve normalized TSH values at 1 to 3 weeks had noneutopic thyroid. All of the infants with eutopic thyroid exhibited normalized TSH at 3 to 5 weeks, and a significantly greater proportion of the infants with eutopic thyroid exhibited normalized TSH at 1 to 3 weeks compared with those with noneutopic thyroid. Stepwise regression analysis demonstrated that US etiology was a significant independent variable for normalization of TSH at 1 to 3 weeks. Conclusions US examination to identify eutopic or noneutopic thyroid provides useful information for determining the starting dose of l-T4 in hypothyroid infants.
ISSN:0022-3476
1097-6833
DOI:10.1016/j.jpeds.2007.12.015