Radioactive iodine in the management of thyrotoxicosis.
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Date
2011
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Abstract
Objective : An audit of the use and outcomes of Radioactive Iodine (RAI) therapy
in the definitive management of thyrotoxicosis at Inkosi Albert Luthuli Central
Hospital (IALCH), KwaZulu-Natal, South Africa.
Methods : The clinical records of all new patients with thyrotoxicosis, referred in a
4 year period between 01/01/2003 and 31/12/2006, were analysed. Response to
RAI was monitored using biochemical parameters (namely, Thyroid Stimulating
Hormone and Free T4 levels). Rates of euthyroidism (cure), hypothyroidism and
hyperthyroidism (treatment failure) were correlated to dose of RAI. Patients were
followed-up for at least 2 years or until the onset of hypothyroidism. The follow-up
period was until 31/12/2007.
Results : One hundred and fourteen patients (37.7%), of a cohort of 302 new
thyrotoxic patients treated with RAI, met the inclusion criteria. Ninety-six patients
(84.2%) had Graves Disease (GD) whilst 18 had Toxic Nodular Disease (TND).
At 2 year follow-up, 91 patients (79.8%) were hypothyroid, 10 (8.8%) were
euthyroid and 13 (11.4%) were hyperthyroid. The average dose of RAI to achieve
euthyroidism was 10mCi and hypothyroidism, 9.7mCi. The average time to achieve
euthyroidism was 5.9 months and 10.1 months to become hypothyroid. Thirty-one
patients (27.2%) remained persistently hyperthyroid after one dose of RAI.
Patients with GD (88.5%) were more likely to become hypothyroid (p < 0.001)
whilst 38.9% of TND patients remained hyperthyroid (p = .001). Baseline TFT values
were significant in terms of outcomes correlated with the prescribed RAI dose i.e
Low Dose (<8mCi) vs. Intermediate Dose (8-9mCi) vs. High Dose (>9mCi)(TSH p =
0.05; FT4 p = 0.003; FT3 p = 0.001).
Conclusion : The majority of patients became hypothyroid over time, in keeping
with reported data. In the public health sector, where early access to RAI (in terms
of waiting times for appointments for RAI) and follow-up are major problems, early
cure is essential to minimize the morbidity of thyrotoxicosis and this may be
achieved with an initial high dose of RAI.
Description
Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2011.
Keywords
Hyperthyroidism., Iodine--Isotopes., Theses--Radiotherapy and oncology.