Effect of acute high dose dobutamine administration on serum thyrotrophin (TSH)

OBJECTIVE The interpretation of thyroid function tests in the setting of severe illness is often complicated by concomitant drug administration which may independently produce changes in thyroid hormone concentrations or even secondary hypothyroidism. Although the effects of dopamine on TSH are well established, the effects of dobutamine, another drug commonly used in the setting of severe illness, on TSH are unknown. The aim of the study was to establish the effect(s) of acute high dose dobutamine on serum TSH concentration. DESIGN AND PATIENTS Thirty subjects undergoing dobutamine stress echocardiogram were compared to twenty controls. Serum TSH was determined between the hours of 0800 and 1000 h at baseline, at maximum dobutamine infusion (20-50 mu g/kg/min and 15 minutes after stopping dobutamine. MEASUREMENTS Serum TSH concentration was measured using a third generation chemiluminescent assay. RESULTS TSH concentration decreased with time in both dobutamine and control subjects and there was an additional statistically significant effect of dobutamine treatment to decrease TSH. TSH concentration remained within the normal range in all subjects who started with normal TSH concentration and remained above normal in the three dobutamine-treated subjects with elevated TSH at baseline. The dobutamine-associated decrease in TSH was still present 15 minutes after discontinuing dobutamine, CONCLUSIONS These results indicate that acute high dose dobutamine lowers TSH by an unknown mechanism. Additional study with prolonged dobutamine infusion is needed to establish the steady state level and physiological consequences of dobutamine-inhibited TSH.