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[Optimal TRH-testdose in children: 1 microgram TRH/kg (i. v.) (author's transl)]
Insights
The optimal dose for the thyrotropin-releasing hormone (TRH) test in children is 1 microgram/kg intravenously. Higher doses do not offer additional clinical information for diagnosing thyroid conditions.
Area of Science:
- Pediatric Endocrinology
- Thyroid Function Testing
- Hormone Assays
Context:
- Previous research established 1 microgram/kg as the optimal TRH test dose in infants.
- This study evaluates the clinical application of this low-dose TRH in a broader pediatric age range.
- Thyroid Stimulating Hormone (TSH) levels are crucial indicators of thyroid function.
Purpose:
- To assess the efficacy and clinical utility of a low-dose TRH stimulation test in children aged 25 months to 16 years.
- To determine if higher TRH doses provide additional diagnostic information compared to the established optimal dose.
- To establish age-specific TSH response thresholds following TRH administration.
Summary:
- A low dose of 1 microgram/kg of TRH intravenously significantly increased TSH levels in all 70 euthyroid children tested.
- TSH responses at 30 minutes were comparable between 1 microgram/kg TRH and 200 micrograms TRH doses, with no added clinical benefit from higher doses.
- Younger children (≤2 years) exhibited higher TSH responses, but basal TSH secretion was age-independent, and an upper threshold of 7.5 microU TSH/ml is applicable for infants two weeks and older.
Impact:
- Confirms 1 microgram/kg intravenous TRH as the optimal and sufficient dose for pediatric thyroid function testing.
- Simplifies TRH testing protocols by demonstrating that higher doses are unnecessary, reducing potential patient burden.
- Provides evidence-based guidelines for interpreting TSH responses in a wide pediatric age group, aiding in accurate diagnosis of thyroid disorders.
Abstract:
In a previous study the optimal TRH test dose of 1 microgram/kg (i v.) was determined in 67 infants between the ages of 2 weeks and 2 years old. At that time the following doses were tested: 0.5 microgram, 1 microgram, 1 microgram/kg, 2 micrograms/kg and 200 micrograms. In the present study the clinical application of this low dose TRH administered to children between the ages of 25 months and 16 years will be reported. There was a significant increase in TSH in all of the 70 euthyroidic children. The 30 minute values after intravenous injection of 1 microgram TRH/kg were 11.7 +/- 4.5 microU/ml (400% increase, upper threshold value 20 microU/ml). The dose of 200 micrograms TRH resulted in a 30 min value of 13.0 +/- 6.6 microU/ml in 30 of the children (430% increase, upper threshold value 20 microU/ml). In children two years old and younger these values were significantly higher. After administering 1 micrograms TRH/kg, the value 17.0 +/- 8.5 microU TRH/ml was measured in 20 children (735--400% increase) and after 200 micrograms TRH, the value 21.0 +/- 7.5 microU/ml (690--200%). The upper threshold value is 36 microU TSH/ml. The TSH basal secretion did not depend on the age of the child. The upper threshold value of 7.5 microU TSH/ml applies to children two weeks of age and older. 1 microgram TRH/kg (i. v.) is the optimal test dose for children. The higher doses do not provide any additional clinical information.