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Factors involved in the rate of fall of thyroid stimulating hormone in treated hypothyroidism
J Raza1, P C Hindmarsh, C G Brook
1London Centre for Paediatric Endocrinology, Great Ormond Street, Hospital for Children, London.
Insights
Thyroid hormone replacement therapy in infants with hypothyroidism is effective. The study found that initial thyroid stimulating hormone (TSH) levels and the cause of hypothyroidism did not impact the rate of TSH normalization.
Area of Science:
- Pediatric Endocrinology
- Neonatal Care
- Thyroid Disorders
Background:
- Congenital hypothyroidism requires timely treatment to prevent developmental issues.
- Thyroid stimulating hormone (TSH) levels are a key indicator of thyroid function and treatment efficacy.
- Understanding factors influencing TSH normalization can optimize infant hypothyroidism management.
Purpose of the Study:
- To investigate the rate of serum TSH concentration decline in hypothyroid infants treated with thyroxine.
- To determine if initial TSH levels or the etiology of hypothyroidism affect the speed of TSH normalization.
Main Methods:
- Prospective study of 32 hypothyroid infants (11 boys, 21 girls) treated with thyroxine (100 µg/m²/24 hours).
- Serum TSH levels were monitored longitudinally post-treatment initiation.
- Etiology of hypothyroidism was assessed using isotope scans in 27 patients (athyrotic, ectopic gland, dyshormonogenesis).
Main Results:
- Serum TSH remained elevated at 3 months (81%), 6 months (62.5%), and 1 year (28%) in a significant proportion of infants.
- The mean age for achieving normal serum TSH was 0.79 years.
- Neither the diagnosis of hypothyroidism nor initial TSH concentrations influenced the rate of TSH decline.
Conclusions:
- Thyroxine treatment leads to a gradual normalization of TSH in infants with hypothyroidism.
- The specific cause of congenital hypothyroidism and initial TSH levels do not appear to significantly alter the time course of TSH normalization.
- Continued monitoring is essential to confirm TSH normalization in treated infants.
Abstract:
The rate of fall of serum thyroid stimulating hormone (TSH) concentrations in 32 hypothyroid infants (11 boys, 21 girls) was studied after starting treatment with thyroxine to determine whether it was influenced by initial TSH concentration or the cause of the hypothyroidism. Of 27 patients who had isotope scans before treatment was started, 11 (40%) were athyrotic, 10 (38%) had an ectopic gland, and six (22%) probably had dyshormonogenesis. Treatment was started with thyroxine at 100 micrograms/m2/24 hours at a mean age of 26 days (range 14-45). Serum TSH concentrations remained increased in 26 (81%) at 3 months, 20 (62.5%) at 6 months, and nine (28%) at 1 year and beyond. The mean age for serum TSH to reach the normal range was 0.79 years (range 0.15-2.1 years). Diagnosis (in 27 patients) and initial results (in 32) made no difference to the rate of fall.