Diagnostic spectrum of congenital hypothyroidism in Turkish children

Background: Congenital hypothyroidism (CH) is classified as transient or permanent. Transient CH can be treated with short-term thyroxine replacement therapy or followed up without therapy, whereas lifelong thyroxine replacement is needed in permanent CH. Determination of the underlying etiology is essential for determination of follow-up strategy. The purpose of the present study was therefore to assess the role of color Doppler ultrasonography (CDU) in etiologic diagnosis of CH together with radionuclide method and grayscale ultrasonography (GSU).

Methods: A total of 182 patients (83 female, 99 male) were evaluated. To determine etiologic diagnosis, the patients underwent a free T4 (fT4), thyroid-stimulating hormone (TSH) and urinary iodine level measurement, and thyroid scintigraphy, perchlorate discharge test, CDU, and GSU.

Results: Fifty-four patients had transient and 97 had permanent CH. Isolated hyperthyrotropinemia was diagnosed in 31 patients. Transient CH was due to iodine deficiency in 22 and excess iodine in 13 patients. In 97 patients with permanent CH, ectopia was present in 32 patients and agenesis of the thyroid gland was found in 22 patients, while 43 were diagnosed with dyshormonogenesis. In the ectopia group, GSU failed to detect ectopic tissues in all cases, whereas CDU was successful in determining the presence of ectopic thyroid in 20 cases. The sensitivity of CDU was 80% in determining ectopic tissue.

Conclusion: To determine etiologic diagnosis, radionuclide methods and sonographic modalities should be assessed together. The gold standard in the diagnosis of ectopic thyroid tissue is thyroid scintigraphy. CDU may be a major supportive diagnostic tool in the evaluation of ectopic thyroid gland.