“Comparison of Thyroid Uptake by Tc – 99m Pertechnetate and Iodine – 131 for Euthyroid & Hypothyroid Patientsâ€

Euthyroidism is defined as normal functioning thyroid gland that occurs with normal serum levels of TSH and T4. Lower than normal T4 levels usually mean its hypothyroidism. This thyroid condition can be treated with radioactive therapy using uptake studies by Iodine-131 and Tc-99m. Oral administration of I-131 has been a commonly accepted procedure for treatment of benign and malignant conditions of the thyroid since the 1940s. However, thyroid uptake using Tc-99m has proven to be more advantageous than with I-131, since the procedure is faster, short half-life (only 6 hours), short retention in the gland, no beta (-) radiation thus providing low dose to the thyroid gland (10000 times less than that of I-131) and the images have better quality for its gamma photon of 140keV. So the aim of this study was to make a comparison between I-131 and Tc-99m for performing thyroid uptake and to correlate them for both euthyroid and hypothyroid patients and hence to standardize a simple and fast method for performing thyroid uptake. This study was made for 87 patients (58 females and 29 males) with ages ranging from 14 to 75 years (mean of 39.2 years) were done with both I-131 and Tc-99m. The type of patients was euthyroid, hyperthyroid and hypothyroid. The correlation and comparison between I-131 and Tc-99m was studied for euthyroid and hypothyroid patients. From this study out of 87 patients 32 were found euthyroid, 12 were hypothyroid and others were hyperthyroid. Out of 32 euthyroid patients 26 patients were positive with both Tc-99m and I-131. 6 patients had negative results with Tc-99m and positive results with I-131. Out of 12 hypothyroid patients 10 patients were positive with both Tc-99m and I-131. 2 patients had negative results with Tc-99m and positive results with I-131. A statistically significant correlation was found between I-131 and Tc-99m data for euthyroid patients (r = 0.49, p-value = 0.005). But for hypothyroid patients (r = 0.56, p value = 0.058) which indicates statistically not significant correlation. Considering I-131 imaging as the gold-standard procedure, Tc-99m had a good correlation with I-131 for the detection of euthyroidism but not for the hypothyroidism. So, the consideration of thyroid structure and function using Tc-99m is a simple, fast, better and efficient method for euthyroid patients according to its advantages over I-131 and also for the good quality correlation of this study. To show better correlation for hypothyroidism; further study should be needed with more patients.