The Study of Thyroid Physiology Using 131I-Sodium-Iodide Uptake Measurements

The measurement of the radioactive iodine uptake (RAIU) provides the most direct study of thyroid physiology by studying the rate of thyroidal accumulation, incorporation, and release of radioiodine. A total 69 subjects with a mean age of 34±13 years (range: 8-70 years) that include 70% females and 30% males, referred to the Institute of Nuclear Medicine & Allied Sciences (INMS), Rajshahi for RAIU measurement were evaluated to investigate their thyroid physiology. The uptake study consisted of oral administration of 3.7–7.4 MBq (100–200 μCi) of 131I as sodium-iodide was performed both at 2 hours and 24 hours. The Mean±SD of RAIU values for euthyroidism, hypothyroidism and hyperthyroidism were found to be 6.3±3.4% at 2h and 9.9±6.8% at 24h, 1.8±0.8% at 2h and 4.2±2.6% at 24h, and 36.5±21.4% at 2h and 54.8±15.9% at 24h, respectively. The RAIU measured in the present study effectively indicate the status of the respective thyroid.