Thyroid Hormone in the Pediatric Intensive Care Unit.

Area of Science:

• Pediatric Endocrinology
• Critical Care Medicine
• Molecular Endocrinology

Background:

• Thyroid hormones regulate growth, development, and metabolism in children.
• Thyroid hormone homeostasis is frequently disrupted in critically ill children, manifesting as decreased T3 and increased rT3.
• Traditional views of these changes as adaptive responses to illness are being challenged by the "inflammatory hypothesis."

Purpose of the Study:

• To review the alterations in thyroid hormone levels during critical illness in children.
• To discuss the potential role of inflammation in mediating these thyroid disturbances.
• To evaluate the potential benefits and safety of thyroid hormone supplementation in critically ill pediatric patients.

Main Methods:

• Review of existing literature on thyroid hormone levels in pediatric critical illness.
• Analysis of the "inflammatory hypothesis" linking cytokines to thyroid dysfunction.
• Evaluation of studies on thyroid hormone supplementation in critically ill children.

Main Results:

• Decreased serum triiodothyronine (T3) and increased reverse triiodothyronine (rT3) are common in pediatric critical illness.
• Thyroid hormone levels correlate with the severity of nonthyroidal illness.
• Evidence suggests inflammation, mediated by cytokines, plays a significant role in thyroid hormone disruption.

Conclusions:

• Thyroid hormone alterations in critically ill children are complex and not fully understood.
• The inflammatory hypothesis offers a compelling explanation for these changes.
• Thyroid hormone (T3) supplementation shows promise for improving outcomes in pediatric ICU patients due to its safety and potential benefits.