131I Hyperthyroidism Therapy Dose Estimation
In Basedow Grave’s Disease there are two alternatives. Either you chose a fixed dose trying to reach an hypothyroid condition or use a formula, with the idea of trying to achieve a euthyroid state. Those using the fixed dose comment that no matter how precise the way you apply the formula, the result may be unpredictable. In addition, it is not easy to estimate the thyroid weight, unless you do it with ultrasound or an objective methodology. There is more consensus in toxic nodule regarding amount to give.
a1) Grave's Disease adult fixed dose = 15 mCi. a2) Autonomous Nodule adult fixed dose = 30 mCi.
In adults use the following formula for Grave's Disease:
b1)
Formula = 0.1 (mCi) x Gland Weight (g)-------------------------------------
Uptake Fraction (%)
In children, McCormack use (2):
b2) Formula
= 0.16 (mCi) x Gland Weight (g)--------------------------------------
Uptake Fraction (%)
Doses in children should be larger in order not to leave any residual thyroid tissue and decrease cancer risk (3). Doses from 200 to 300 uCi/g gland have been used based on this rationale.
References:
1 Jairo Wagner, Hans Graf, Marcia Khaled Puñales, Suzana Nesi França. DIAGNOSTICO Y TRATAMIENTO DE LAS MALFORMACIONES Y DISFUNCIONES DEL TIROIDES, p: 177 -184 in: Medicina Nuclear Aplicaciones Clínicas. Eds: I. Carrio - P. González. Editorial Masson, Barcelona España, 2003.
2 McCormack S, Mitchell DM, Woo M, Levitsky LL, Ross DS, Misra M. Radioactive iodine for hyperthyroidism in children and adolescents: referral rate and response to treatment.Clin Endocrinol. 2009 Dec;71(6):884-91.
3 Rivkees SA, Dinauer C. An
optimal treatment for pediatric Graves' disease is radioiodine. J Clin
Endocrinol Metab. 2007 Mar;92(3): 797-800.