RESUMO
INTRODUCTION: Thyroxine is essential for nervous system development. Subclinical hypothyroidism (SCH), also known as mild thyroid failure, is associated with impaired cognitive function in children and mood disorders in adults. Serotonin is also involved in brain development as well as in mood and behavior modulation. The possible interaction between thyroid function tests, serum serotonin concentrations, and emotional intelligence (EI) was studied. METHODS: A total of 224 schoolchildren from the Peloponnese, Greece, aged 11-19, were included in the study, of whom 26.3% had SCH. Emotional quotients (EQ), such as well-being, self-control, emotionality, and sociability, were assessed using the TEIQue-ASF questionnaire, and TSH, fT4, and serum serotonin concentrations were also evaluated. RESULTS: Children and adolescents with SCH had a lower EQ total score (p < 0.001), EQ well-being score (p = 0.025), EQ self-control score (p = 0.029), EQ emotionality score (p = 0.029), and EQ sociability score (p = 0.010) and lower serum serotonin concentrations (p < 0.001). CONCLUSIONS: Children and adolescents with SCH exhibited lower EI scores and lower serum serotonin concentrations when compared with age-matched healthy controls.