The effect of lithium in radioiodine therapy of metastatic well differentiated thyroid carcinoma
- National Inst. of Health and Clinical Endocrinology Branch, Bethesda, MD (United States); and others
Lithium carbonate retards the release of I-131 from thyroid tumors. To evaluate the effect of lithium on increasing the radiation dose to metastatic well differentiated thyroid carcinoma in radioiodine therapy, we studied the biologic half life of I-131 in metastic lesions (15 patients, 36 lesions) before and after administration of lithium carbonate. All patients had prior thyroidectomy and were withdrawn from T4 for 6 weeks and from T3 for 2 weeks. Following oral administration of I-131(1.5 - 5 mCi), scintigraphies of all functioning metastases were recorded daily up to 10 days. After background subtraction and correction for physical decay of I-131, the biological half life of I-131(T{sub {1/2}biol}) in each lesion was computed using a monoexponential curve fitting. After the initial set of measurements, the patients were placed on lithium carbonate 900-1200mg/day, to achieve blood levels of 0.8 to 1.2 mg/dl and then the above procedure was repeated. In 29 of the 36 metastatic lesions, T{sub {1/2}biol} was prolonged after lithium carbonate treatment. Effective half life of I-131(T{sub {1/2}eff}) also increased in these lesions from 2.74{plus_minus}0.84 to 3.68{plus_minus}0.88 days (mean {plus_minus}SD, p < 0.0001). The mean increase of T{sub {1/2}eff} was 34.2%(median:34.3%,range:3.6%-116.9%). Among 15 patients, 10 patients showed prolonged T{sub {1/2}eff} in all lesions, 4 patients showed prolonged T{sub {1/2}eff} in some of the lesions. The fractional increase of T{sub {1/2}eff}(FIT {sub {1/2}eff}) with lithium carbonate therapy was linearly related to the fractional increase of T{sub {1/2}biol}(p<0.0001). However FIT{sub {1/2}eff} was inversely proportional to the initial T{sub {1/2}biol}(p<0.01) indicating that the effectiveness of lithium carbonate to augment the radiation dose was greater in tumor with rapid iodine release and poor iodine retention.
- OSTI ID:
- 441585
- Report Number(s):
- CONF-950603-; ISSN 0161-5505; TRN: 96:002093-0009
- Journal Information:
- Journal of Nuclear Medicine, Vol. 36, Issue Suppl.5; Conference: 42. annual meeting of the Society of Nuclear Medicine, Minneapolis, MN (United States), 12-15 Jun 1995; Other Information: PBD: May 1995
- Country of Publication:
- United States
- Language:
- English
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