Congenital goitre due to "thyroid peroxidase-iodinase defect"
Niepomniszcze, H.; Coleoni, A.H.; Targovnik, H.M.; Iorcansky, S.; Degrossi, O.J.
Acta Endocrinologica 93(1): 25-31
1980
ISSN/ISBN: 0001-5598 PMID: 7355662 Document Number: 159777
A 16 yr old male cretin with congenital goitrous hypothyroidism and 95% discharge in the perchlorate test underwent thyroidectomy. Thyroid studies disclosed negligible peroxidase (TPO) activity in the tyrosine iodinase assay, 6 nmol I- incorporated/g (normals: 220-410). Using the same particulate preparations, a high activity was obtained in the guaiacol assay, 485 U/mg vs. 176 U/mg of a control gland. Goiter TPO was solubilized by treating the thyroid pellets with deoxycholate, trypsin and acetone. Soluble goiter TPO was further purified on Sephadex G-200. By this procedure, a single peak of enzyme activity for oxidizing guaiacol was obtained, although no activity was found for iodinating tyrosine. I2 formation, as measured by the triiodide assay, was only 28% of that expected for normal TPO when compared for guaiacol oxidation. This abnormal TPO apparently was the cause of the congenital hypothyroidism of the patient. The term "thyroid peroxidase-iodinase defect" is suggested for defining this newly found inborn error.