Correlation study on serum TT3 and FT3 levels with disease severity in elderly tuberculosis patients — Exploration of the value of thyroxine level-guided Anti-TB individualized medication

Tuberculosis (TB) remains a major global public health issue, with elderly patients (≥65 years) at higher risk of severe progression—driven by immune decline, polypharmacy, and impaired drug metabolism, which complicate anti-TB medication management in geriatrics. As the thyroid’s primary active hormones, TT3 and FT3 regulate metabolism and immunity, both critical for medication tolerance, therapeutic response, and prognosis in elderly TB patients. Low TT3 and FT3 levels correlate with poor outcomes in elderly severe pulmonary TB, often alongside higher anti-TB toxicity and lower efficacy. Aligned with intelligent pharmacy’s goal of optimizing high-risk care, this study explores the correlation between serum TT3 and FT3 and disease severity in elderly TB patients—and verifies T3 as a practical biomarker for geriatric anti-TB risk stratification and dose adjustments. A retrospective prospective observational study was conducted, enrolling 509 TB patients admitted to our hospital from January 2022 to December 2023. Patients were divided into a severe group (n=270) and non-severe group (n=239) based on severe TB development within 1 week of admission. Venous blood samples were collected on admission to measure serum TT3 and FT3; patient demographics and 1-week severe manifestations were recorded. TT3 and FT3 levels on admission were significantly lower in the severe group. Severe patients had significantly lower TT3 and FT3 than non-severe patients (both P<0.001). Pearson analysis showed a significant negative correlation between TT3 and FT3 and severe pulmonary TB (TT3: r=-0.541, P<0.001; FT3: r=-0.423, P<0.001). ROC curve analysis confirmed high evaluative value of TT3 and FT3 for severe TB (AUC=0.841 and 0.827, respectively). Subgroup analysis revealed that negative correlations persisted in both elderly and non-elderly groups: TT3 correlation was slightly weaker in the elderly (r=-0.516 vs. non-elderly r=-0.529), while FT3 correlation was stronger (r=-0.491 vs. non-elderly r=-0.380). Serum TT3 and FT3 levels are closely associated with disease severity in elderly TB patients and serve as potential biomarkers for geriatric anti-TB individualized medication. Notably, FT3’s stronger correlation in the elderly makes it more reliable for guiding anti-TB risk stratification and dose adjustments.