Hyperthyroidism without elevated levels of thyroxine and triiodothyronine in a patient with pulmonary tuberculosis

We have reported a case of toxic thyroid adenoma with low T3 and low T4 syndrome in a patient who received antituberculous drugs for active pulmonary tuberculosis. Search for thyroid-hormone-binding antibodies was negative. Thyroid lobectomy was done and histologic examination confirmed toxic thyroid adenoma; two months after operation the patient was clinically and biologically euthyroid. During the course of a severe nonthyroidal illness, normal thyroid hormone levels must be regarded as an indicator of hyperthyroidism. In addition, we believe that rifampin has a significant effect on thyroid function tests and results of thyroid physiology.