Study of mutations in PAX-8 and TSH receptor genes after determination of congenital hypothyroidism etiology: importance of color Doppler ultrasonography, thyroid uptake and scan and intravenous perchlorate test

Abstract

The etiology of congenital hypothyroidism (CH) plays an important role in determining disease severity, outcome and treatment. Permanent primary CH results frequently from development defects of the thyroid gland (dysgenesis) or thyroid hormone synthesis defect (dyshormonogenesis). We will evaluate patients from APAE-Sao Caetano with diagnosis of primary CH to determine their etiology using Color-doppler ultrasonography (USDC), thyroid radioisotope iodine uptake (RAIU) scan and intravenous perchlorate test (PCIV). USDC can provide not only morphology, but also blood flow in topic and ectopic thyroid glands. As it is a rapid, innocuous and sensitive exam, it can be adopted as a diagnosis tool for the initial investigation of CH. RAIU scan indicates a functioning thyroid gland with regard to iodine uptake. Normal scan findings associated or not to goiter alert the physician to a probable dyshormonogenesis, afterwards perchlorate test is mandatory for differential diagnosis. The perchlorate test with intravenous vial will enables more precise diagnosis, without side effects and misinterpretation seen in oral test. Combining color-Doppler ultrasonography and thyroid scan to intravenous perchlorate test, the etiologic diagnosis will precisely be done. We will also search for mutations in most frequently found genes: PAX-8 and TSH receptor genes associated to thyroid dysgenesis. Therefore we will amplify the etiologic and genetic diagnosis repertory of CH and counseling of disease’s risks to patient and his family. (AU)