HYPOTHALAMIC-PITUITARY-THYROID (HPT) AXIS IN CHRONIC-ALCOHOLISM .1. HPT AXIS IN CHRONIC-ALCOHOLICS DURING WITHDRAWAL AND AFTER 3 WEEKS OF ABSTINENCE

Thyroxine (T-4), free T-4 (fT(4), triiodothyronine (T-3), free T-3 (fT (3))l reverse T-3 (rT(3)), thyrotropine (TSH), thyroxine binding globu lin (TBG), and T-3 uptake were measured in 14 chronic alcoholics durin g withdrawal and after 21 days of abstinence. Results were compared wi th those of 16 healthy volunteers. During withdrawal, the fT(4) and fT (3) concentrations were subnormal, whereas the respective protein-boun d fractions were normal. T-4 T-3, and TBG increased during the abstine nce period, T-3 and TBG being significantly higher than in normals at the second measuring time. T-3 uptake values fell, but remained well w ithin the normal range at both measuring times. During abstinence, the fT(3) levels remained significantly lower than in healthy subjects. r T(3) concentrations decreased, but not significantly. The TSH values w ere normal throughout. These results showed numerous abnormalities in the hypothalamic-pituitary-thyroid axis in alcoholics, the reasons for which are as yet unclear. The following possible interpretations are suggested: The abnormally low serum fT(3) and fT(4) levels during with drawal might reflect an increase in tissue uptake. The increases in T- 4-and partly those in T-3-during abstinence seem to reflect increased binding by TBG, the level of which rose markedly for reasons as yet un known. If increases in TBG during abstinence are taken into account, t he decreases in rT(3) concentrations may reach the level of statistica l significance. These falls in rT(3) concentrations may reflect an inc rease in rT(3) metabolization (deiodination) in various tissues, inclu ding the CNS, leading to a reduction in serum rT(3) bioavailability. F actors such as liver disease, protein caloric malnutrition, and ''psyc hological stress''' do not fully explain all these abnormalities. A di rect effect of ethanol on intracellular thyroid hormone metabolism and /or function seems conceivable.