Juan J Díez, Emma Anda, Victoria Alcazar, Juan C Galofré, Cristina Familiar, María J Pamplona-Civera, Silvia González-Martínez, Ana Herrero-Ruiz, María R Alhambra, Alejandra Planas, Cecilia Sánchez-Ragnarsson, Tomás Martín, Beatriz Rodriguez-Jiménez, Mireia Mora, Aida Orois, Reinaldo Sánchez-Barrera, Julia Sastre
Adoption of ATA 2025 reference-range TSH targets substantially increases the proportion of low risk DTC survivors classified as adequately treated. Nevertheless, treatment adequacy remains strongly shaped by dose instability and selected provider workload attributes.
BACKGROUND: For low-risk differentiated thyroid carcinoma (DTC) survivors with excellent or indeterminate response, the 2025 American Thyroid Association (ATA) guidelines endorse assay-specific reference-interval thyrotropin (TSH) targets, potentially simplifying levothyroxine titration versus ATA 2015 fixed cutoffs.
OBJECTIVE: To assess whether endocrinologist and hospital-level characteristics influence levothyroxine treatment adequacy in low-risk DTC with excellent/indeterminate response, and to compare adequacy under ATA 2015 versus ATA 2025 frameworks.
METHODS: Multicenter, retrospective study including 978 adults managed by 16 endocrinologists. Dynamic risk stratification (DRS) status and serum TSH at last visit defined adequacy: ATA 2015 (0.5-2.0 mcU/ml for excellent; 0.1-0.5 mcU/ml for indeterminate) vs ATA 2025 (within local reference interval for both). Physician and hospital characteristics were compared across adequacy strata. Multilevel logistic regression (random intercept for physician) evaluated patient- (age, follow-up, dose instability) and physician-level predictors.
RESULTS: Under ATA 2015 criteria, 383 of 954 (40.1%) were adequately controlled, compared with 650 of 963 (67.5%) under ATA 2025 criteria. In those with >2 years' follow-up, adequacy increased from 41.5% (364/878) to 68.8% (608/884) from ATA 2015 to ATA 2025. Dose instability independently predicted lower adequacy in both frameworks (ATA 2015: aOR 0.183, 95% CI 0.129-0.260; ATA 2025: aOR 0.110, 0.078-0.156; both p<0.001). With ATA 2025, additional inverse associations included older age (aOR 0.980/year; p=0.001), female physician sex (vs male; aOR 0.244; p=0.037), and higher new-patient volume (aOR 0.967/patient; p=0.009).
CONCLUSIONS: Adoption of ATA 2025 reference-range TSH targets substantially increases the proportion of low risk DTC survivors classified as adequately treated. Nevertheless, treatment adequacy remains strongly shaped by dose instability and selected provider workload attributes.