Dopamine and the sick euthyroid syndrome in critical illness.
OBJECTIVE
The sick euthyroid syndrome is a poorly understood hallmark of critical illness. Dopamine is a natural catecholamine with hypophysiotrophic properties, that is used as an inotropic agent of first choice in intensive care medicine. We explored the effect of dopamine infusion (5 micrograms/kg/min) on the sick euthyroid syndrome of critically ill patients.


METHODS
In a prospective, randomized, controlled and open-labelled study of critically ill, adult polytrauma patients (n = 12), we evaluated the effect of prolonged (83-296 hours) dopamine infusion (5 micrograms/kg/min i.v.) on the thyroid axis. The effect of brief (15-21 hours) dopamine administration was documented in an additional randomized, controlled, cross-over study involving 10 patients. The median age of the studied patients was 29 (16-83) years.


METHODS
Serum TSH concentrations were measured by IRMA. The TSH profiles were obtained by blood sampling every 20 minutes for 9 hours during two consecutive nights. Serum T4, T3 and reverse T3 concentrations were measured by RIA once per study night.


RESULTS
Withdrawal of prolonged dopamine infusion was found to elicit a tenfold increase of serum thyrotrophin concentrations, a 57 and 82% rise of T4 and T3 respectively, and an increase of the T3/rT3 ratio, resulting in virtual normalization of the thyroid axis within 24 hours. The brief dopamine infusion was documented to have a suppressive effect on the thyroid axis within 24 hours.


CONCLUSIONS
Dopamine infusion appears to induce or aggravate the sick euthyroid syndrome in critical illness. As a consequence, the sick euthyroid syndrome of severely ill patients receiving dopamine may be not an adaptive mechanism, but a condition of iatrogenic hypothyroidism.
Van den Berghe
G
G
Department of Intensive Care Medicine, University of Leuver, Belgium.
de Zegher
F
F
Lauwers
P
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016638:Critical Illness; D003864:Depression, Chemical; D004298:Dopamine / Q000494:pharmacology*; D005067:Euthyroid Sick Syndromes / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D013961:Thyroid Gland / Q000187:drug effects*; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood; D014285:Triiodothyronine, Reverse / Q000097:blood
D013963:Thyroid Hormones; D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D013972:Thyrotropin; D013974:Thyroxine; D004298:Dopamine