Objective: In differentiated thyroid carcinoma (DTC), TSH suppression with levothyroxine (L-T4) is a standard treatment for reducing tumor recurrence after total thyroidectomy. This study aims to evaluate the effect of long-term TSH suppression on the development of sarcopenia and frailty in elderly patients with DTC.
Method: Seventy patients aged 60 years and older with stable TSH levels during the last year and under L-T4 due to DTC were included in the study. The anterior thigh muscle thickness was measured by ultrasound and the Sonographic Thigh Adjustment Ratio (STAR) Index was calculated. Reduced muscle strength was diagnosed with a hand grip test. Walking speed, Fried Frailty Index and the Physical Activity Scale for the Elderly (PASE) scores were calculated.
Results: Median age of the patients was 65 years (min-max: 60-80) and 64.3% were women. The patients were followed up for 11 (2-30) years. Median TSH was 1.10 µIU/ml (IQR=1.13). While active suppression (TSH<0.1) was applied to 4.3% of the cases, 22.9% had low (0.1-0.49), 60.0% had low-normal (0.5-2), and 12.9% had normal (2.1-4) TSH levels. The anterior thigh muscle thickness was 37.5 (9.5) mm, and the STAR Index was 1.21 (0.39). Muscle mass was reduced in 35.7% of the cases. TSH was found to be significantly low in the group with reduced muscle mass compared to the group having no muscle mass reduction (0.71 (1.07) vs 1.20 (1.08); P=0.014). Reduced muscle strength was present in 17.2% of the patients in the hand grip test. TSH levels of the reduced muscle strength group was lower than normal muscle strength group (0.66 (0.97) vs 1.18 (1.17); P=0.037). According to the Fried Frailty Index, 58.5% of the cases was prefrail and/or frail while the remaining cases were robust. TSH was lower in the group at high risk of frailty than in the robust group (0.77 (0.88) vs 1.39 (1.07); P=0.002). TSH showed a positive correlation with walking speed (r=0.258, P=0.031) and STAR Index (r=0.254, P=0.034), and a negative correlation with Fried Frailty Index (r=−0.399, P=0.001). TSH below 1.325 µIU/ml was found to increase the risk of frailty with a sensitivity of 80.49% and a specificity of 58.62% (AUC=0.719, P=0.001). Logistic regression analysis indicated that TSH was an independent predictor of frailty development (P=0.006).
Conclusion: In elderly patients with TSH suppression due to DTC, muscle strength and muscle mass decrease, and the risk of frailty increases in the long term. Close follow-up of these patients for sarcopenia and frailty is recommended.
13 May 2023 - 16 May 2023