Related Experiment Videos
Transient secondary hypothyroidism in children after cardiac surgery
M Bettendorf1, K G Schmidt, U Tiefenbacher
1Department of Pediatrics, University of Heidelberg, Germany.
Insights
Children undergoing cardiac surgery can experience transient secondary hypothyroidism, leading to prolonged recovery. This condition may impact cardiac and respiratory function post-operation.
Area of Science:
- Pediatric Endocrinology
- Cardiovascular Surgery
- Critical Care Medicine
Background:
- Congenital heart defects often require surgical intervention in pediatric patients.
- Cardiac surgery can induce significant physiological stress, potentially affecting endocrine function.
- Thyroid hormone plays a crucial role in metabolic regulation and organ function.
Purpose of the Study:
- To assess thyroid hormone status in children before and after cardiac surgery.
- To investigate the relationship between thyroid hormone levels and postoperative outcomes.
- To identify potential contributing factors to altered thyroid hormone levels post-cardiac surgery.
Main Methods:
- Measured plasma concentrations of thyroid-stimulating hormone (TSH), thyroxine (T4), free thyroxine (fT4), triiodothyronine (T3), reverse triiodothyronine (rT3), thyroglobulin (Tg), and urinary iodine excretion in 132 children.
- Collected data preoperatively and daily for 21 days postoperatively.
- Analyzed correlations between thyroid hormone levels and clinical outcomes like ventilation duration and medication use.
Main Results:
- Post-surgery, children showed significantly decreased TSH, T3, T4, fT4, and Tg, with increased rT3.
- Maximal changes in TSH and rT3 preceded alterations in other thyroid hormones and Tg.
- Lower postoperative T3 levels correlated with prolonged mechanical ventilation and higher doses of inotropic/vasopressor medications.
Conclusions:
- Transient secondary hypothyroidism is observed in children following cardiac surgery.
- This hormonal imbalance may contribute to postoperative cardiac and respiratory dysfunction, delaying recovery.
- Further research into the potential benefits of thyroid hormone replacement therapy is warranted.
Abstract:
Thyroid hormone status was assessed in 132 children with congenital heart defects undergoing cardiac surgery (median age 3.1 y; range 2 d to 16.2 y). Plasma TSH, thyroxine (T4), free thyroxine (fT4), triiodothyronine (T3), reverse triiodothyronine (rT3), thyroglobulin (Tg), and urinary iodine excretion were measured before and every other day after cardiac surgery (d 1-21). After surgery we observed strikingly low plasma concentrations of TSH (0.4 mU/L; 0.2-1.3), T3 (0.6 nmol/L; 0.3-1.2), T4 (48.9 nmol/L; 12.9-82.4), IT4 (12.9 pmol/L; 5.1-19.3), and Tg (9.4 micrograms/L; 1.5-20.6), whereas rT3 plasma concentrations increased (0.13 pmol/L; 0.05-0.3; n = 40). The maximal post-operative changes of TSH and rT3 preceded changes of T3, T4, fT4, and Tg. Postoperative urinary iodine excretion increased significantly (n = 109). Thyroid hormone plasma concentrations were lowest after cardiopulmonary bypass operations and in patients treated with dopamine. In patients with postoperative T3 plasma concentrations less than 0.6 nmol/L (n =52) the period of mechanical ventilation and intensive care treatment was significantly prolonged. Furthermore, the cumulative doses of inotropic and vasoactive catecholamines and furosemide were significantly higher in this patient group. Our results demonstrate transient secondary hypothyroidism in children after cardiac surgery that may contribute to postoperative cardiac and respiratory dysfunction and may delay recovery. Possible benefits of thyroid hormone replacement therapy need to be thoroughly examined.