Abstract 55: Ultrasonography as an imaging modality in congenital hypothyroidism – A descriptive study

Background: 99mTc-pertechnetate scanning is considered ideal for etiological diagnosis of congenital hypothyroidism, but it leads to radiation exposure and financial burden. Also exogenous thyroxine replacement interferes uptake in scintigraphy studies. Ultrasonography is a relatively simple and noninvasive procedure but may miss ectopic thyroid tissue and dyshormonogenesis. Aims: To evaluate the use of sonography as the primary imaging modality in congenital hypothyroidism. Results: In this cross sectional study of fifteen patients, 73% (n=11) were female and 26% (n=4) male. The mean age of the patients was 1.84 years. The Thyroid Stimulating Hormone levels at diagnosis ranged from 40-404 mIU/ml. Ultrasonography studies were available for 100% (n=15) patients and scintigraphy studies for 26% (n=4) patients. Ultrasonography studies showed normal thyroid gland size in 46% (n=7) patients, hypoplasia of gland in 6% (n=1) patient, and gland was not visualized in 46% (n=7) patients. 99mTc-pertechnetate scanning was done in 4 patients, of which 75% (n=3) patients showed features of dyshormonogenesis, and in all these patients the thyroid was visualized normally on ultrasonography. 25% (n=1) patient had ectopic thyroid gland and thyroid on uptake studies. Conclusion: Ultrasonography is an important tool in the diagnosis of congenital hypothyroidism when Radionuclide uptake studies are not feasible, or when the patient is already on exogenous thyroid replacement.