8423 Pattern of Thyroid Function Tests Variation Among an Elderly Population

Abstract Disclosure: M.I. Chiamolera: Employee; Self; Fleury Medicina e Saude. J.P. Morgado: Employee; Self; Fleury Medicina e Saude. C.M. Ferrer: Employee; Self; Fleury Medicina e Saude. O.J. Pereira: Employee; Self; Grupo Fleury. J.V. Lima: Employee; Self; Fleury Medicina e Saude. P.R. Saddi: Employee; Self; Fleury Medicina e Saude. J.G. Vieira: Owner/Co-Owner; Self; Fleury Medicina e Saude. R.M. Maciel: Owner/Co-Owner; Self; Fleury Medicina e Saude. R.M. Biscolla: Employee; Self; Fleury Medicina e Saude. Introduction: The understanding of thyroid function data has evolved in recent decades, revealing a consistent rise in age-related TSH levels as demonstrated by various research groups. The advent of Big Data, marked by an abundance of studies with expansive datasets, has mitigated the former limitations of sample sizes. Consequently, utilizing clinical laboratory databases to study the behavior of these tests has emerged as a feasible and innovative solution.Objective: This study aims to investigate the patterns of TSH and free T4 (fT4) levels in a population aged 60 years and above. The analysis utilizes thyroid function test database from Latin American lab. Methods: A retrospective analysis was conducted on data from 8,694,807 blood samples, initially filtering for TSH analysis based on criteria such as concentration within the reference values of fT4, absence of negative anti-thyroid antibodies, and no medication usage. The TSH assays were performed in a Roche Platform, and fT4 assays were performed in Roche, Beckman and Siemens platforms. Statistical analyses were achieved using Shapiro-Wilk, Kruskal-Wallis, Dunn´s post-hoc test, Cohen´s D test, and others. Results: From the initial group, 439,690 TSH samples, 79,928 Beckman fT4 (fT1b), 35,623 Siemens fT4 (fT4s) and 324,139 fT4 (fT4r) were selected to be studied. TSH analyses using the Kruskal-Wallis test (KWT) showed a difference between age groups (p-value<2.2e-16); the magnitude of this effect showed through the Cohen D test (CDT) pointed to a small difference between the 18-59 and the over-80 age groups. The fT4b analyses showed significant differences between the age groups (p-value<2.2e-16) in the KWT. The CDT showed the most significant difference between 18-59 to over 80 age groups. For the fT4s analyses, there were significant differences between the age groups (p-value<7.473e-09) in the KWT. The CDT showed that this difference is only perceived between the 18-59 and over-80 age groups. Finally, for the fT4s analyses, there were significant differences between the age groups (p-value<2.2e-16) in the KWT. The CDT showed that this difference is only perceived between the 18-59 and over-80 age groups. Conclusion: The analyses of this large dataset showed essential differences in both TSH and fT4 (3 different methods) with age. This data showed the importance of establishing age-specific reference values to correctly assess thyroid function in this population and avoid misdiagnosis of hypothyroidism. Presentation: 6/1/2024