Serum 25-hydroxyvitamin D and health-related quality of life in patients with papillary thyroid carcinoma: a prospective cohort study.

[BACKGROUND] The incidence of papillary thyroid carcinoma (PTC) is rising worldwide. Despite its excellent prognosis, many PTC patients experience impaired Health-Related quality of life (HRQoL). Vitamin D exerts pleiotropic effects on musculoskeletal, immune, and psychological health, but its impact on HRQoL in PTC patients remains unclear.

[METHODS] This prospective cohort study consecutively recruited patients with PTC from January 2024 to August 2025. Baseline serum 25-hydroxyvitamin D concentrations were measured before treatment. The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) and The Thyroid Cancer-Specific Quality of Life Questionnaire (THYCA-QoL) were applied to assess HRQoL. Associations between serum 25-hydroxyvitamin D and HRQoL domains were examined using rank-transformed general linear models, spearman correlation, multivariable linear regression and binary logistic regression. A nomogram was developed to predict the probability of weight gain in HRQoL domains and evaluated using Harrell's C-index and bootstrap calibration.

[RESULTS] Among 600 patients, 27.8% had vitamin D deficiency, 69.5% had insufficiency, and 2.7% had sufficiency. Patients with sufficient vitamin D had better physical functioning and lower social functioning scores than those with deficiency or insufficiency ( = 0.002). Vitamin D was positively correlated with multiple functioning domains and negatively correlated with specific symptoms (all  < 0.05). In linear and logistic regression, higher vitamin D levels were independently associated with better physical and role functioning and fewer symptom burdens, and reduced the odds of impaired physical functioning (OR = 0.986,  = 0.016) and neuromuscular and weight gain symptoms (all  < 0.05). The nomogram showed fair discrimination (C-index 0.628) and good calibration.

[CONCLUSION] Suboptimal vitamin D status was common among patients with PTC. Higher vitamin D levels were associated with better physical and role functioning and fewer neuromuscular, psychological, and weight gain symptoms. Assessment of vitamin D status may be considered as part of supportive care when clinically indicated.