thyronines and Syndrome

"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.

Topics: Body Temperature Regulation; Catecholamines; Glucose; Humans; Infant, Newborn; Iodide Peroxidase; Ketone Bodies; Models, Biological; Respiratory Distress Syndrome, Newborn; Shock, Septic; Syndrome; Thyroglobulin; Thyroid Diseases; Thyroid Gland; Thyronines; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

1. The relationship between the length of incubation, hatching, hypoxic condition, thyroid hormones and the occurrence of ascites were studied in embryos of 2 broiler lines differing in susceptibility to the ascites syndrome. 2. Both the time of external pipping (ep) and hatching of embryos from the ascites-resistant (AR) broiler line was earlier compared to the ascites-sensitive line (AS). The interval between internal pipping (ip) and ep was the same between the lines, but the interval between ep and hatching was shorter in the resistant line. 3. The T3 and T4 concentrations in plasma of the AS line were lower compared to the AR line. 4. Analyses of partial pressures of oxygen (pO2) and carbon dioxide (pCO2) in the air cell of the egg revealed that at day 18 the AS embryos had lower pO2 and higher pCO2 concentrations compared to the AR embryos. 5. The delay in hatching of the AS embryos might induce a more pronounced and/or extended hypoxic environment, thereby creating an environment that evokes ascites.

Topics: Animals; Ascites; Carbon Dioxide; Chick Embryo; Chickens; Disease Susceptibility; Eggs; Hypoxia; Incidence; Oxygen; Poultry Diseases; Syndrome; Thyronines; Time Factors; Triiodothyronine