Abstract
BACKGROUND: Postoperative reduction of thyroid hormones (TH), particularly triiodothyronine (T3), is frequently observed but poorly characterized in pediatric surgical patients. This study aimed to identify risk factors for postoperative TH reduction in pediatric patients, analyze the association between anesthetic factors and perioperative TH changes, and explore the relationship between postoperative TH reduction and clinical outcomes in pediatric cardiac surgery patients. METHODS: We conducted a retrospective analysis of 233 pediatric patients (ages 0-18) undergoing surgery and anesthesia at Shanghai Children's Medical Center between 2014 and 2023. Patients were categorized into low thyroid hormone (LTH) and non-LTH groups based on postoperative free T3 (FT3) and/or free thyroxine (FT4) levels below the lower reference limits. Multivariable logistic and ridge regression were used to identify independent predictors. Clinical outcomes were analyzed in a sub-cohort of cardiac surgery patients. RESULTS: Postoperative LTH occurred in 78 patients (33.5%). Longer anesthesia duration, surgical duration, higher ASAphysical status (III-V), cardiac surgery, and cardiopulmonary bypass (CPB) use were associated with LTH in univariate analysis (P < 0.05). Multivariable regression identified anesthesia duration as a significant independent risk factor (OR = 1.335, 95% CI: 1.144-1.557, P < 0.001), a finding confirmed by ridge regression. This risk remained consistent regardless of surgery type (P for interaction = 0.747) or CPB use (P for interaction = 0.826). In an exploratory analysis of cardiac surgery patient, severe TH reduction (low both FT3 and FT4) was significantly associated with longer postoperative hospital stays (P = 0.035). CONCLUSION: Longer anesthesia duration is independently associated with postoperative TH reduction in children. In cardiac surgery, the degree of this reduction correlates with prolonged hospitalization. These findings highlight anesthesia duration as a potentially risk factor for postoperative thyroid hormone reduction, which may inform perioperative management and warrant further investigation into underlying mechanisms.