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Symptomatic hypothyroxinemia with normal TSH levels in preterm infants
Insights
Preterm infants with low thyroxine (hypothyroxinemia) showed symptoms of congenital hypothyroidism. Thyroid replacement therapy rapidly resolved these symptoms, suggesting its benefit in such cases.
Area of Science:
- Neonatology
- Pediatric Endocrinology
- Thyroid Disorders
Background:
- Congenital hypothyroidism can present with symptoms like prolonged jaundice and lethargy.
- Preterm infants are at risk for various endocrine disturbances.
- Hypothyroxinemia, characterized by low serum thyroxine, requires careful evaluation in neonates.
Purpose of the Study:
- To describe clinical features associated with hypothyroxinemia in preterm infants.
- To evaluate the efficacy of thyroid replacement therapy in these infants.
- To recommend further research on the incidence and management of neonatal hypothyroxinemia.
Main Methods:
- Case series of eight preterm infants with hypothyroxinemia.
- Clinical assessment for symptoms resembling congenital hypothyroidism.
- Biochemical evaluation including serum thyroxine, thyroid stimulating hormone, and thyroid binding globulin.
- Initiation of thyroid replacement therapy and monitoring of symptom resolution.
- Follow-up after therapy cessation to assess long-term outcomes.
Main Results:
- All eight preterm infants presented with symptoms such as prolonged jaundice, lethargy, constipation, and hoarse cry.
- Laboratory findings included low serum thyroxine with normal thyroid stimulating hormone and thyroid binding globulin.
- Thyroid replacement therapy led to rapid resolution of clinical symptoms and normalization of thyroid hormone levels.
- Infants demonstrated normal growth, development, and thyroid function upon follow-up after therapy cessation.
Conclusions:
- Hypothyroxinemia in preterm infants can mimic congenital hypothyroidism clinically.
- Thyroid replacement therapy appears beneficial for resolving symptoms and normalizing thyroid status.
- Further prospective studies and randomized controlled trials are warranted to confirm incidence and optimal management strategies.
Abstract:
The authors report eight preterm infants with hypothyroxinemia who developed clinical features similar to those described in congenital hypothyroidism: prolonged jaundice, hypoactivity, lethargy, constipation, edema, and hoarse cry. All had low serum thyroxine, normal thyroid stimulating hormone, and normal thyroid binding globulin levels. After exclusion of other causes for the symptoms, thyroid replacement therapy was started, resulting in rapid resolution of symptoms and return to euthyroid status. Follow-up of these infants after cessation of therapy revealed normal growth and development and normal thyroid function. The authors therefore recommend a prospective study to investigate the incidence of hypothyroxinemia, frequency of associated clinical features, and the benefits of thyroid replacement therapy based on a randomized controlled trial.