title: Reduced serum T4 and T3 and their altered serum binding after burn injury in rats.
abstract: Total T4 and T3 concentrations are often suppressed in burned patients. 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 light:dark cycle of 14:10 hr. Groups (N = 9-15) of BURN, SHAM (anesthesia, fur clipped, no burn) and CON (controls) were sacrificed on postburn days 8 and 14. T4 and T3 (radioimmunoassay), free indices (FT4I and FT3I = respective total T4 or T3 X in vitro charcoal T3 uptake, T3U), and free concentrations (FT4 and FT3 = total T4 or T3 X respective equilibrium dialyzable fraction, T4DF or T3DF) were not different between CON and SHAM. Compared to SHAM, mean T4 and FT4I (by about 48% of respective SHAM means on both days), TT3 (by 36, 43%), and FT3I (by 38, 45%) (days 8, 14) were suppressed in BURN (all p less than 0.001). T4DF (both days) and T3DF (day 14) were significantly elevated in BURN, demonstrating a deficit in serum binding, but T3U was not. FT4 (by 26, 22%) and FT3 (by 33, 34%) (day 8, 14) were significantly lower in BURN. On either day, covariance analyses (BURN vs. combined CON + SHAM) correlated FT4I or FT3I with respective FT4 or FT3 (all p less than 0.001, slopes not different in BURN vs. CON + SHAM), but the lower FT4I and FT3I in BURN significantly overestimated (all p less than 0.001) the depression of respective FT4 and FT3 in BURN.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D002056:Burns / Q000097:blood* / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000097:blood* / Q000378:metabolism; D014284:Triiodothyronine / Q000097:blood* / Q000378:metabolism
chemical_list: D014284:Triiodothyronine; D013974:Thyroxine