Rapid thyroidal iodine turnover in hyperthyroid patients: Incidence and impact on outcome of I-131 therapy (Rx)
- Univ. of Iowa Hospitals and Clinics, Iowa City, IA (United States); and others
It has been suggested that rapid thyroidal iodine turnover (RTIT) may be frequent in hyperthyroid patients and that it could cause not only I-131 therapy failures but also high radiation doses to the blood from circulating protein bound I-131 (JNM 73;14:379A). We investigated the incidence and importance of this phenomenon by comparing 4 hr to 24 hr uptake ratios with the success of I-131 therapy (3.7-5.5 MBq/gm of thyroid). Of 525 hyperthyroid patients treated at our institution between 1980 and 1993, 460 had both 4 and 24 hr uptake measurements: 370 were female, 90 male, mean age 42 years. Clinical diagnosis was Graves` disease in 402, non-Graves` disease in 58. Of the 460, 27 patients were lost to follow-up after the first I-131 Rx, 6 after the second Rx. Defining rapid turnover as early uptake {ge} late uptake, we found 71 of 460 hyperthyroids (15%) to have rapid thyroidal I-131 turnover with all but 2 in patients with Graves` disease. Of 22 patients with RTIT who failed 1st I-131 Rx, 18 (82%) were successfully treated with 2nd I-131 Rx; and of 29 with nonrapid turnover, 27 (93%) had a successful 2nd I-131 Rx. 17 of 24 (71%) patients were converted to nonrapid after the 1st I-131 Rx. The results (a) confirm a relatively high incidence of rapid thyroidal iodine turnover in hyperthyroid patients, (b) reveal a near 50% failure rate for first I-131 Rx in such patients vs. 11% for non-RTIT, (c) demonstrate a reversion to non-RTIT for most RTIT patients after first I-131 Rx, (d) show the 4 to 24 hour uptake ratios to be a guide for treatment outcome.
- OSTI ID:
- 441582
- Report Number(s):
- CONF-950603--
- Journal Information:
- Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 36; ISSN 0161-5505; ISSN JNMEAQ
- Country of Publication:
- United States
- Language:
- English
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