Increased peroxidase activity in pendred's syndrome with hypothyroidism

Abstract

An 8-year-old boy with goiter and bilateral nerve deafness had a 46% discharge of radioiodine after thiocyanate administration. He was clinically euthyroid. Although the serum total T4 was low (2.4 μg/100 ml) and TSH was significantly high (181 μU/ml), the serum total T3 was normal (152 ng/100 ml). It was considered that the increased release of TSH by the feedback mechanism in response to the low T4 resulted in a quite normal level of serum T3. The thyroid gland demonstrated a low stable iodine content, an increase in MIT/DIT ratio and a decrease in iodothyronine. The thyroglobulin behaved normally in Sephadex G-200 chromatography and immunoreaction. Thyroid tissue exhibited increased peroxidase activity as measured by I-3 formation. Increased peroxidase activity may be related to the observed increase in serum level of TSH. © 1976, Tohoku University Medical Press. All rights reserved.