AJP - Endocrinology and Metabolism, Vol 272, Issue 2 E191-E200, Copyright © 1997 by American Physiological Society
Hormone-specific alterations of T4, T3, and reverse T3 metabolism with recent ethanol abstinence in humans
E. M. Kaptein
Department of Medicine, University of Southern California, Los Angeles 90033, USA.
Effects of recent alcoholic withdrawal on thyroxine (T4),
3,5,3'-triiodothyronine (T3), and reverse T3 (rT3) metabolism were
determined by serum tracer kinetic studies in recently abstinent alcoholics
without overt hepatocellular injury or caloric deprivation. Data were
compared with those of normal subjects using a three-pool model, with
rapidly and slowly equilibrating pools exchanging with serum. Significant
differences included 1) reduced serum total rT3 levels (to 69% of normal)
and rT3 degradation rates (to 61%); 2) increased rT3 binding in rapidly (to
557%) but reduced binding in slowly (to 13%) equilibrating tissues, with
opposite effects on rT3 fractional transfer rates to serum from rapidly (to
7.5%) and slowly equilibrating sites (to 669%); 3) increased T4 fractional
transfer rates from serum to rapidly equilibrating tissues (to 122%); and
4) increased T4 binding to both rapidly (to 195%) and slowly (to 190%)
equilibrating tissues. T3 kinetics were not significantly altered. Thus
recently abstinent alcoholics have hormone-specific alterations of T4, T3,
and rT3 transfer, distribution, and metabolism distinct from other
nonthyroidal illnesses or caloric deprivation. Furthermore, these data
indicate separate transfer processes for T4, T3, and rT3 from serum to
tissue sites and hormone-specific tissue binding characteristics in humans
in vivo.
