Relationship of Preoperative Thyroid Dysfunction to Clinical Outcomes in Pediatric Cardiac Surgery

Context Thyroid function may be assessed in children before cardiac surgery because of concerns that hypothyroidism or thyrotoxicosis might adversely affect cardiac function perioperatively. However, the relationship between preoperative thyroid dysfunction and surgical outcomes is unknown. Objective Determine the relationship between preoperative thyroid dysfunction and outcomes of pediatric cardiac surgery. Methods Retrospective cohort study (January 2005 to July 2019). Setting Academic pediatric hospital. Patients All patients <19 years old who underwent cardiac surgery with cardiopulmonary bypass and had thyrotropin (TSH) measured within 14 days preoperatively. Exclusion criteria included neonates (<= 30 days), preoperative extracorporeal life support, salvage operations, or transplantation procedures. Main Outcome Measures Subjects were stratified by preoperative TSH concentration (mIU/L): low (<0.5), normal (0.5-5), mildly high (5.01-10), or moderately high (>10). Outcomes were compared among subjects with normal TSH (control) and each group with abnormal TSH concentrations. The primary outcome was 30-day mortality. Secondary outcomes included time to extubation, intensive care unit and hospital length of stay, and operative complications. Results Among 592 patients analyzed, preoperative TSH was low in 15 (2.5%), normal in 347 (58.6%), mildly high in 177 (29.9%), and moderately high in 53 (9.0%). Free thyroxine was measured in 77.4% of patients and was low in 0 to 4.4% of subjects, with no differences among TSH groups. Thirty-day mortality was similar among TSH groups. There were no differences in any secondary outcome between patients with abnormal TSH and patients with normal TSH. Conclusion Preoperative mild to moderate subclinical hypothyroidism was not associated with adverse postoperative outcomes in children undergoing cardiopulmonary bypass procedures.