MON-588 Characteristics of Overt Thyrotoxicosis When TSH Is Measured in All Patients in Nonsurgical Departments

Introduction: Thyroid dysfunction in patients in non-surgical departments is common and often caused by nonthyroidal illness syndrome (NTIS) and medications. The aim of this study was to characterize overt thyrotoxicosis when TSH is measured routinely in medical departments. Methods: This is a retrospective study of adult patients from medical departments, who were admitted to our medical center for any reason. TSH level was measured on admission routinely in all patients, FT3 and FT4 levels were measured in patients with low TSH. In order to characterize the patients with overt thyrotoxicosis, three groups were defined and compared: 1) T4 group: overt thyrotoxicosis with high FT4 included a random sample of patients who had low TSH and only high FT4 levels. 2) T3 group : overt thyrotoxicosis with high FT3 included all patients with low TSH and high FT3 levels (with and without high FT4 levels). 3. NTIS group : Included a random sample of patients with low TSH and FT3 levels and FT4 levels below the middle of the normal range. Results: TSH levels were measured on admission in 77,147 inpatients and 82 (0.11%) patients met the criteria for T3 group. The T4 and the NTIS groups included a random sample of 123 patients and 119 patients respectively. The T4 group was 5.1 times more prevalent than the T3 group. The T3 group had much more elevated FT3 level compared to FT4 elevation in T4 group, 85.4% of the patients in T4 group had FT4 level less than 1.25 times the upper normal level. In addition, the T4 group had low FT3 levels, 79.7% of patients had FT3 levels in the lower half of the norm and less. Compared to the T3 group, the T4 group was older, had less supraventricular arrhythmia, more systemic or inhaled corticosteroids treatment and higher CRP levels (all p