Evaluation of serum levels of thyroid hormones in macaws (Ara spp.) by chemiluminescence

ABSTRACT This paper investigated the efficiency of chemiluminescence in obtaining serum concentrations of thyroid hormones in twenty-three macaws kept in captivity, from two sexes [male (n=10) and female (n=12)] and two species [Ara ararauna (n=12) and Ara chloropterus (n=11)]. Reference intervals for the hormones sampled were indicated and the effects of species and sex on these values were analyzed. Concentration values of total T4, free T4, free T3 and TSH varied respectively from 0,3 to 2,5µg/dL (average =0,94µg/dL), 0,11 - 0,46ɳg/dL (average = 0,28ɳg/dL), 3,59 - 1,46pg/mL (average =2,42pg/mL), and 0,01 - 0,12µUI/mL (average= 0,04µUI/mL). There was interaction between species and sex (P<0.05) on total T4 concentrations. Males had higher values than females in Ara ararauna, while females had higher values than males in Ara chloropterus. Sex effect was not observed (P>0.05) for concentrations of free T4, free T3 and TSH, but species effect was observed (P<0.05) for free T3 concentrations. In this case, concentrations of free T3 were lower in Ara ararauna than in Ara chloropterus. The results of this study suggest that it is possible to measure serum concentration of thyroid hormones in macaws by means of chemiluminescence method, as long as relevant variations between different species and sexes are taken into account.