SAT467 Monitoring TSH Over Time May Not Be Necessary in Patients With Thyroid Nodules

Abstract

Abstract Disclosure: S. Kaul: None. A. Gupta: None. Introduction: A substantial number of patients with thyroid nodules receive monitoring of blood thyroid stimulating hormone (TSH) levels after the initial diagnosis. There is not enough literature supporting long-term monitoring of blood TSH levels in these patients with thyroid nodules. The objective of this study was to evaluate the change in blood TSH level in patients with known thyroid nodules over time and to determine if repeat blood TSH testing is required in these patients. We hypothesized that monitoring of blood TSH level is not warranted in patients with thyroid nodules in the absence of a history of medical conditions or medications that are known to affect thyroid hormone levels. Methods: We studied 100 patients aged 18 to 99 years at the Dayton VA Medical Center with at least one thyroid nodule on imaging studies from January 2010 to December 2016 with normal blood TSH level at time of the diagnosis of the thyroid nodule. Subjects with abnormal thyroid hormone level, history of hot thyroid nodule, autoimmune thyroid disease (on imaging or blood work), thyroid or pituitary surgery, radioactive iodine treatment, neck irradiation, or usage of thyroxine or any other medications known to affect thyroid hormone levels were excluded. Blood TSH level at the time of diagnosis of thyroid nodule and after were retrospectively studied and analyzed for 100 subjects. Normal blood TSH level range at time of diagnosis was noted to be 0.35-5.50 uIU/mL or 0.35-4.00 uIU/mL depending on the assay method used. Normal repeat blood TSH level range was noted to be 0.35-5.50 uIU/mL, 0.35-4.00 uIU/mL, or 0.55-4.78 uIU/mL depending on the assay method used. Results: 100 subjects with normal blood TSH at the time of diagnosis of their thyroid nodule had blood TSH level monitoring for an average time period of 5.74 years. Out of the 100, six subjects (6%, 95% CI [2.52%, 12.73%]) developed an abnormal blood TSH level in a mean time period of 6.94 years. One subject’s initial blood TSH level increased from 3.38 uIU/mL to 7.76 uIU/mL after 8.52 years. This subject did not receive treatment with thyroxine. In the other five subjects, blood TSH level decreased to below normal range in a mean time period of 6.63 years and ranged from 0.25-0.52 uIU/mL. Blood TSH level remained within normal range for 94 subjects in a mean time period of 5.67 years. Conclusion: Monitoring of blood TSH level over time may not be required in most patients with thyroid nodules in the absence of symptoms, medical conditions, or medications that are known to affect thyroid hormone levels. Presentation Date: Saturday, June 17, 2023