Background: Hyperthyroidism is a common systemic disorder where Graves’ disease is
known as the leading cause of the disease. Thyroid stimulating hormone, T4 and T3 antibody assay
is usually performed for the diagnosis of the pathology. However, with uncertainty in the results
and in order to estimate the magnitude and the exact cause of the disease, radioactive iodine uptake
(RAIU) test is recommended. The aim of this study is to evaluate underlying pathology in the patients
presenting hyperthyroidism using RAIU test results.
Methods: This is a cross-sectional retrospective study conducted on the patients with hyperthyroidism
referred to Shahid Madani Hospital in Khorramabad. Data regarding the biochemical analysis
and RAIU test was collected from the records and a questionnaire based on demographic and
clinical information was completed for each patient.
Results: Of 137 patients presenting hyperthyroidism, 62.04% presented with Graves’ disease,
24.08% with toxic multinodular goiter and 13.86% with toxic adenoma. 24-hour RAIU test
showed that the percent of radioiodine uptake was most in toxic adenoma with 67.7%, Graves’ disease
53.5% and multinodular goiter 39%, respectively. From the age-based analysis, we found that
Graves’ was most common in 20-30 years old individuals accounting for 34%, multinodular goiter
in 50+ aged individuals with 36.3% and toxic adenoma was most prevalent in 30-40 and 50+ aged
patients, with 26.3%. In our population of interest, 81.8% toxic multinodular goiter patients were
Conclusion: Our study presents the outcome of RAIU tests in hyperthyroidism based on the underlying
pathologies. We also conclude, in light of other findings, that Graves’ disease is the most
common cause of hyperthyroidism in our population.