Thyroid function during and after cardiopulmonary bypass in children

Background: The aim of the study was to elucidate the changes in thyroid function during and after cardiopulmonary bypass (CPB) in children. Methods: Triiodothronine (T3), thyroxine (T4), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were determined preoperatively, at specific times throughout CPB, and serially up to 48 h postoperatively, in 10 children (median age 35, range 23-68 months) undergoing elective surgery for congenital heart disease. Results: T3 decreased from 2.01+/-0.08 preoperatively to 0.94+/-0.10 nmol/l 24 h postoperatively (P<0.05). T4 levels followed a pattern similar to changes in T3. FT4 increased from 17.4+/-0.7 preoperatively to 30.0+/-0.4 pmol/l after 30 min of CPB (P<0.05). TSH decreased from 2.44+/-0.43 preoperatively to 0.93+/-0.21 24 h postoperatively (P<0.05). Conclusion: T3, T4 and TSH are significantly depressed after open heart surgery in children.