Hypothalamic-pituitary-thyroid axis changes in children after cardiac surgery.
BACKGROUND
Hypothalamic-pituitary-thyroid axis changes in critical illness result in nonthyroidal illness syndrome (NTIS) characterized by abnormal TSH and thyroid hormone levels. It is unclear whether NTIS is adaptive or maladaptive. Some have suggested that NTIS adversely affects outcome, but there are limited data in children.


OBJECTIVE
Our objective was to determine the natural history of NTIS in children undergoing cardiac bypass surgery and to correlate these changes with outcome and illness severity.


METHODS
Thyroid function was measured in 21 patients, aged 1-11 yr, preoperatively and postoperatively twice daily on postoperative days (POD) 0-3 and daily thereafter until POD 7. Pediatric Logistic Organ Dysfunction and inotrope scores and pediatric intensive care unit, hospital, and ventilation days were measured and statistically analyzed in relation to thyroid function.


RESULTS
All patients exhibited NTIS within the first day postoperatively. TSH recovered by POD 4. Total T(3), free T(3) index, and T(3) uptake were still below preoperative levels on POD 7. NTIS changes correlated to prolonged hospital stays with increased pediatric intensive care unit and mechanical ventilation days and also showed strong relations with Pediatric Logistic Organ Dysfunction and inotrope scores. The T(3) measures drawn within 6-14 h from surgery were predictive of clinical outcome. Alterations in illness severity preceded changes in thyroid function.


CONCLUSIONS
NTIS was present in this population of critically ill children with some of the biochemical changes not corrected by 8 d postoperatively. The degree of NTIS was related to and predictive of clinical outcome and illness severity.
Marks
Seth D
SD
Department of Pediatrics, Division of Endocrinology, University of Alberta, Stollery Children's Hospital, 1C4 Walter Mackenzie Health Sciences Centre, 8440 112th Street, Edmonton, Alberta, Canada. smarks@ualberta.ca
Haines
Christina
C
Rebeyka
Ivan M
IM
Couch
Robert M
RM
D006348:Cardiac Surgical Procedures; D002648:Child; D002675:Child, Preschool; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D018729:Fontan Procedure; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D007223:Infant; D015278:Intensive Care Units, Pediatric; D008297:Male; D013961:Thyroid Gland / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine; D004298:Dopamine