Reduced Serum T sub 4 and T sub 3 and Their Altered Serum Binding after Burn Injury in Rats
ARMY INST OF SURGICAL RESEARCH FORT SAMHOUSTON TX
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In humans, a reduction in the circulating concentrations of bioactive thyroid hormones is characteristic of nonthyroidal illness NTI. In burned patients, similar to patients with other NTI, serum concentrations of 3,5,3 - triiodothyronine T3 and often tetraiodothyronine T4, as well as the indices of free hormonal concentrations, FT3I and often FT4I index total hormone concentrations, FT3I and often FT4Iindex total hormone concentration times T3 uptake, are suppressed. To investigate the significance of such changes, we have characterized serum T4 and T3 after full-thickness scald burns 60 body surface under anesthesia of 270-gm male Sprague-Dawley rats housed in a lightdark cycle of 1410 hr. Because of failure of the in vitro charcoal T3 uptake to account for this serum bindng abnormality, the results are most consistent with a burn-induced circulating inhibitors for binding of T4 and T3, not only to transport proteins but also in vitro charcoal, perhaps similar to inhibitors previously described in the sera of patients with various nonthyroidal illnesses. The thermally traumatized rat appears to be a good model for thyroid changes in burns and other nonthyroidal illness.
- Anatomy and Physiology
- Medicine and Medical Research