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Response to TRH in suspected hypopituitarism
Insights
Thyrotrophin-releasing hormone (TRH) tests revealed abnormal thyroid-stimulating hormone (TSH) responses in 35% of children receiving growth hormone (GH) therapy, even when clinically euthyroid. Further research is needed for interpretation.
Area of Science:
- Pediatric Endocrinology
- Neuroendocrinology
- Clinical Chemistry
Background:
- Growth hormone (GH) deficiency diagnosis and therapy in children.
- Thyroid function assessment in pediatric patients.
- Role of thyrotrophin-releasing hormone (TRH) stimulation tests.
Purpose of the Study:
- To analyze TRH stimulation test results in children undergoing GH therapy.
- To investigate abnormal thyroid-stimulating hormone (TSH) responses in euthyroid children.
- To correlate TRH test abnormalities with GH deficiency aetiology.
Main Methods:
- Retrospective analysis of 405 TRH stimulation tests in UK children (1977-1981).
- Categorization of TSH responses based on criteria to minimize assay variation.
- Comparison of TRH test results between hypothyroid, clinically euthyroid, and normal children.
Main Results:
- 93% of hypothyroid children showed abnormal TRH tests.
- 35% of clinically euthyroid children with normal thyroxine had abnormal TSH responses to TRH.
- Abnormal TRH tests were more frequent in euthyroid children with defined GH deficiency aetiology.
Conclusions:
- Abnormal TRH stimulation tests occur in a significant proportion of euthyroid children receiving GH therapy.
- Interpretation of abnormal TRH tests in this group requires further investigation.
- Regular thyroid function monitoring is recommended for these patients pending further clarification.
Abstract:
A retrospective analysis was made of 405 thyrotrophin-releasing hormone (TRH) stimulation tests on children who were successful applicants for growth hormone (GH) therapy in the UK between 1977 and 1981 inclusive. Thyroid-stimulating hormone (TSH) responses to TRH were divided into normal and those indicating pituitary or hypothalamic disease on the basis of criteria which eliminated variation in TSH assay between laboratories. Among children known to be hypothyroid 93% had abnormal TRH stimulation tests, but 35% of those children who were clinically euthyroid and who had normal serum thyroxin levels also had abnormal TSH responses to TRH. Abnormal TRH tests in the latter group were most common in euthyroid children who had GH deficiency with clearly defined aetiology and least common in those with idiopathic GH deficiency. Further work is required to clarify the interpretation of an abnormal TRH stimulation test in this group of children, but until this is done, such patients should be kept under regular review with respect to thyroid function.