APPLICATIONS OF RADIOIODINE-132 TO MEASUREMENTS OF DAY TO DAY CHANGES IN HUMAN THYROID FUNCTION
Radioiodine-- 132 of half-life 2,3 hours has been used for over 2,000 measurements of human thyroid function. It is formed continuously from a Te/sup 132/ suspension and can be distilled from it by a simple and rapid method. A 5 mc source of Te/sup 132/ (half-life 77 hours) initially yields 3 to 5 mc of I/sup 132/ by such distillation and still yields 30 to 50 mu c of I/sup 132/ per distillation after 3 weeks' decay. Doses of 6 mu c or iess are given orally to fasting subjects and the ratio of the radioactivity in neck and thighs is determined by gamma radiation counting two hours later. Apparatus is described which allows these measurements to be made simultaneously, a statistically reliable result being obtainable in 2 to 4 minutes counting on a normal subject after a 8 mu c dose. One considerable advantage of using I/sup 132/ in place of I/sup 132/ is the very large reduction in radiation dosage received by the subject. Calculations will be presented for beta and garama dosage from I/sup 132/ and I/sup 131/ to the gonads and to normal and abnormal thyroid glands in the foetus, neonate, child, pregnant, and non-pregnant adult. Radiation to the normal adult thyroid gland from I/sup 132/ is less than 1% of that from I/sup 131/ , yet the sensitivity of most counting systems per microcurie is equal or greater for I/sup 132/ than for I/sup 131/. The value of using I/sup 132/in tests on children and pregnant women is stressed. A further advantage of I/sup 132/ as compared with I/sup 131/ is that tests may be repeated daily without interference due to thyroid radioactivity from previous tests, I/sup 132/ decaying to 0.1% of its initial activity in 24 hours. Investigations are reported showing the range of results obtained with hyperthyroid, normal, and myxoedematous subjects and the day-to-day variation in thyroid activity of normal subjects. The changes in thyroid function during normal pregnancy and the puerperium are described, but no changes are found in relation to the normal menstrual cycle. (auth)
- Research Organization:
- Univ. of London, Eng.
- NSA Number:
- NSA-13-006100
- OSTI ID:
- 4272905
- Report Number(s):
- A/CONF.15/P/277
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Comparative effects of iodine-132 and iodine-131 in rat thyroid glands
Fission Products and the Dairy Cow