Syndromes related to defective iodothyronine metabolism.
"Syndromes related to defective iodothyronine metabolism" have been frequently observed in clinical practice. As for methodological and pathophysiological reasons T4, T3, rT3 and TSH estimations are of limited value in these situations, thus, the interpretation of the laboratory findings becomes frequently difficult. Furthermore determining the individual "whole body"- or "organ-thyroid state" requires more than measuring the serum concentrations of thyroid hormones. Iodothyronine metabolism is strongly organ specific, therefore, alterations in plasma thyroid hormone concentrations cannot reflect the specific cellular and subcellular thyroid hormone concentrations of individual organs. However, there is some experimental evidence, that disease-induced alterations in plasma thyroid hormone levels are a simple reflection of the catabolic state of the organisms. At present the biological implication of altered thyroid hormone economy in non-thyroidal illness should not be considered as an energy sparing, i.e. protein sparing effect, anymore: Thyroid hormones in their physiological concentrations act as anabolic hormones. There is no general indication for substituting diminished T3. Up to now, preliminary data suggest the benefit of T3-substitution in septic shock or in "respiratory distress syndrome". However, the possible benefit of improved cardiovascular of respiratory function should be compared carefully to the harm of the therapy, i.e. T3-induced increase in protein catabolism or possible deterioration in preexisting ischemic heart disease: From a clinical point of view, most of non-thyroidal illness-induced changes in ITH-metabolism seem to implicate a pitfall in physician's diagnosis of the thyroid state rather than a therapeutic question.
D001833:Body Temperature Regulation; D002395:Catecholamines / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007453:Iodide Peroxidase / Q000378:metabolism; D007657:Ketone Bodies / Q000378:metabolism; D008954:Models, Biological; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology; D012772:Shock, Septic / Q000503:physiopathology; D013577:Syndrome; D013954:Thyroglobulin / Q000378:metabolism; D013959:Thyroid Diseases / Q000209:etiology*; D013961:Thyroid Gland / Q000503:physiopathology*; D013970:Thyronines / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism; D013974:Thyroxine / Q000378:metabolism; D014284:Triiodothyronine / Q000378:metabolism; D014285:Triiodothyronine, Reverse / Q000378:metabolism
D002395:Catecholamines; D007657:Ketone Bodies; D013970:Thyronines; D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D013972:Thyrotropin; D013954:Thyroglobulin; D007453:Iodide Peroxidase; D005947:Glucose; D013974:Thyroxine