Biochemical indicators of euthyroid sick syndrome in critically ill children

Area of Science:

• Pediatric critical care medicine
• Endocrinology
• Clinical biochemistry

Background:

• Euthyroid sick syndrome (ESS), a condition of altered thyroid function tests in critically ill patients, is common in pediatric intensive care units (PICUs).
• Understanding the prevalence and predictors of ESS is crucial for managing critically ill children and predicting outcomes.

Purpose of the Study:

• To determine the prevalence and predictors of euthyroid sick syndrome (ESS) in a pediatric intensive care setting.
• To investigate the association between thyroid function tests, specifically free triiodothyronine (fT3), and mortality in critically ill children.
• To identify biochemical indicators associated with ESS progression.

Main Methods:

• A retrospective study included 386 children admitted to the PICU between January 2015 and March 2020 who had thyroid function tests (fT3, fT4, TSH) performed.
• ESS was defined by decreased fT3 with normal or decreased fT4 and TSH levels.
• Statistical analyses, including multivariate regression, were used to identify predictors of ESS and the association between fT3 levels and 28-day mortality.

Main Results:

• Euthyroid sick syndrome (ESS) was diagnosed in 141 (36%) of the 386 children studied.
• The ESS group exhibited a higher 28-day mortality rate (8.5% vs. 3.7%).
• Blood urea nitrogen (BUN), albumin, platelet count, and lactate were identified as independent predictors of ESS progression. Low fT3 levels (<2.31 pg/mL) were significantly associated with increased 28-day mortality (p=0.001).

Conclusions:

• Blood urea nitrogen, albumin, lactate, and platelet count are significant independent risk factors for euthyroid sick syndrome (ESS) progression in critically ill children.
• Free triiodothyronine (fT3) levels are correlated with mortality in this population, suggesting its potential utility in mortality prediction indices for pediatric intensive care patients.