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Serial TSH determination after T/sub 3/ withdrawal or thyroidectomy in the therapy of thyroid carcinoma. [I-131]

Journal Article · · J. Nucl. Med.; (United States)
OSTI ID:5825357
Exogenous triiodothyronine (T/sub 3/) was substituted for levothyroxin or desiccated thyroid in 13 athyrotic patients previously treated for papillary, follicular, or mixed papillary-follicular carcinoma of the thyroid. After 4 weeks, T/sub 3/ therapy was discontinued and serial determinations of plasma thyroid stimulating hormone (TSH) concentrations were made. A roughly exponential rise in TSH values, corresponding to a doubling time of 2 days, was observed until a level of 40 ..mu..IU/ml was reached, after which the curve passed through a maximum at 20 days. The mean time required for a level of 50 ..mu..IU/ml was 11 days, and this time is suggested for TSH determination before I-131 imaging of patients with thyroid cancer. Plasma TSH values in eight patients following total thyroidectomy showed a much slower and more variable rise, with a mean doubling time of 7.6 days. Weekly TSH levels beginning at 15 days will provide a rational basis for I-131 imaging in this group, in whom a longer period of hypothyroidism will be required before imaging and therapy. Adherence to these protocols should minimize the duration of hypothyroidism in patients undergoing I-131 treatment of thyroid carcinoma.
Research Organization:
Univ. of Arizona, Tucson
OSTI ID:
5825357
Journal Information:
J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 20:9; ISSN JNMEA
Country of Publication:
United States
Language:
English