[Clinical significance of triiodothyronine (T3) measurement]

The clinical significance of T3 assay is related to the discovery of T3 thyrotoxicosis, a form of hyperthyroidism caused by an overproduction of alone T3 with normal value of T4. We evaluated the prevalence and the clinical features of this form in a group of 850 subjects who were submitted to clinical examination and hormonal thyroid assay. We showed that T3 thyrotoxicosis is a mild condition of hyperthyroidism.