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Standardized radioiodine therapy in Graves' disease: the persistent effect of thyroid weight and radioiodine uptake on outcome
Author(s) -
BRUIN T. W. A.,
CROON C. D. L.,
KLERK J. M. H.,
ISSELT J. W.
Publication year - 1994
Publication title -
journal of internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.625
H-Index - 160
eISSN - 1365-2796
pISSN - 0954-6820
DOI - 10.1111/j.1365-2796.1994.tb00837.x
Subject(s) - medicine , thyroid , confidence interval , radioiodine therapy , graves' disease , incidence (geometry) , nuclear medicine , prospective cohort study , iodine , thyroid disease , endocrinology , gastroenterology , thyroid cancer , physics , optics , materials science , metallurgy
. Objective. To assess the incidence of hypothyroidism, euthyroidism, and recurrent hyperthyroidism following a standard dose of Na 131 I (3.7 MBq or 100 μCi) per g thyroid tissue, adjusted for radioiodine tracer uptake. Design. A single‐centre prospective follow‐up study from January 1990 to December 1992. Setting. Academic Hospital in Utrecht, the Netherlands. Subjects. Newly diagnosed patients with Graves' disease ( n = 148). Interventions. Radioiodine treatment at a standard dose of 3.7 MBq or 100 μCi per g thyroid tissue. Main outcome measures. Confidence interval testing of resulting thyroid status, defined by biochemical criteria. Results. The overall cure rate was 70% (103 of 148 subjects), confidence interval (CI) 62–77%. A 90% incidence of hypothyroidism was found in patients with a small thyroid (less than 20 g). Recurrent hyperthyroidism was found significantly more often in subjects with a thyroid weight exceeding 60 g compared to those who had a thyroid of 9–59 g. More recurrences were found in subjects in the highest tertile of a 24‐h radioiodine uptake test (> 80% uptake) compared to those in the lowest tertile (< 60% uptake). Conclusions. No uniform treatment results expressed per thyroid weight category were obtained, in spite of standardizing the treatment Na 131 I dose (3.7 MBq per g thyroid). Graves' patients with a thyroid smaller than 20 g and those with less than 60% 24‐h radioiodine uptake have a 50–90% chance of hypothyroidism at the 12‐month follow‐up.