The authors discuss thyroid hormone changes in critically ill children. The hypothalamo-pituitary-thyroid axis and thyroid hormone metabolism are influenced by acute diseases, surgical procedures and various drugs used in intensive care. In neonates and infants requiring intensive care true hypothyroidism must be taken into consideration as it may complicate the course of the underlying disease and threaten the further development of the central nervous system.

        Key words: thyroid hormones, low tri-iodothyronine syndrome, povidone-iodine, hypothyroidism