SUN-399 Use Of The 36-point Thyroid Symptom Questionnaire To Guide Optimal Thyroid Hormone Replacement Therapy

Abstract Disclosure: T.D. Hoang: None. A.A. Patel: None. A.J. Spiro: None. N.L. Watson: None. M.K. Shakir: None. Levothyroxine monotherapy (LT4) is the standard of care for treating patients with hypothyroidism; however, a subset of patients have bothersome symptoms despite normal thyroid stimulating hormone (TSH) values. Some patients may benefit from combination thyroid hormone replacement therapy, like desiccated thyroid extract (DTE) or levothyroxine with liothyronine (LT4+LT3). Objective: To determine whether the 36-Point Thyroid Symptom Questionnaire (TSQ-36) can guide which patients should trial combination replacement therapy. Methods: We performed a post-hoc subgroup analysis of two previous randomized, double-blind, cross-over studies (total n=143) to evaluate patient symptoms on treatment with LT4, DTE, and LT4+LT3. The TSQ-36 was completed at the end of each treatment period. Patients were stratified based on their TSQ-36 score on LT4: Low Symptoms (TSQ-36: 0-12), Moderate Symptoms (TSQ-36: 13-24), High Symptoms (TSQ-36: 25-36). Mean TSQ-36 scores were compared on LT4, LT4+LT3, and DTE. Treatment-blinded preference of therapy was also stratified by TSQ-36 score on LT4.Results:In Cohort 1, the Moderate-High Symptoms group had significantly lower TSQ-36 scores on DTE vs LT4 (p=0.01).In Cohort 2, the High Symptoms group had significantly lower TSQ-36 scores on DTE vs LT4 (p<0.01) and on LT4+LT3 vs LT4 (p<0.001). The Moderate Symptoms group had significantly lower TSQ-36 scores on DTE vs LT4 (p=0.02). The Low Symptoms group had significantly lower TSQ-36 scores on LT4 vs DTE (p=0.03) and LT4+LT3 (p=0.02).Patients who preferred combination therapy had significantly higher TSQ-36 scores than patients who preferred LT4. Conclusion: The TSQ-36 can be used to quantify patient symptoms and guide thyroid hormone replacement therapy. Patients on LT4, with moderate-to-severe symptoms despite normalization of TSH, should consider a trial of combination therapy. Patients with low symptoms on LT4 should generally avoid combination therapy. Presentation: Sunday, July 13, 2025