artigo original Padronizao de Valores de Captao Tiroidiana Com 123 I

ABSTRACT Reference Values for Thyroid 24 Hours 123 I Uptake.To establish references for thyroid 24h 123 I uptake value (TUV), wereviewed 475 patients who had freeT4 and TSH dosages, and TUV mea-sured 24h after the administration of 123 I. The patients were separated in3 groups: hyperthyroid, euthyroid and hypothyroid, according to thyroidhormone results. The mean and standard deviation (SD) of the TUVs werecalculated for each group. We used the unpaired T test to compare themeans and ROC curves to evaluate the best TUV to separate the groups.The mean and SD of TUVs for the groups were: hyperthyroid (36.5% ±16.5%), euthyroid (14.4% ± 5.48%) and hypothyroid (13.7% ± 7.5%). Theunpaired T test showed statistically significant difference between hyper-thyroid and euthyroid groups (p< 0.01). There was no significative differ-ence between hypothyroid and euthyroid groups (p= 0.55). The 23% TUVhas the best sensitivity (80%) / specificity (93%) ratio to separate hyper-thyroid from euthyroid groups. There was not a good TUV to separateeuthyroid form hypothyroid groups. In conclusion, it can be established23% as the optimal superior limit for the normal uptake values. However,it was not possible to establish a suitable inferior limit, due to the expres-sive overlay of TUVs of hypothyroid and euthyroid groups. (Arq BrasEndocrinol Metab 2005;49/3:425-432)Keywords: Thyroid uptake; Iodine-123; Reference values; T-test; ROCcurves