Quality of Life, Muscle Strength, and Fatigue Perception in Patients on Suppressive Therapy With Levothyroxine for Differentiated Thyroid Carcinoma

Abstract

The aim of this study was to evaluate the fatigue perception, the muscle function, and the health-related quality of life (QoL) in subclinical hyperthyroidism (SCH) induced by levothyroxine in the treatment of differentiated thyroid carcinoma, in comparison with a group of euthyroid (EU) subjects. A cross-sectional study with 38 SCH individuals and 54 EU subjects was performed. They were submitted to Short Form-36 and Chalder questionnaires to evaluate QoL and fatigue, respectively. The tests performed to evaluate muscle function of upper and lower limbs were: maximum quadriceps isometric strength (QS); quadriceps fatigue resistance (T50% QS), QS at 30 seconds (QS30s); quadriceps functional capacity (QFC); maximum isometric handgrip strength (HS); fatigue handgrip resistance (T50% HS), HS at 30 seconds (HS30s); and functional capacity of the shoulder. The SCH patients had worse muscle function, regarding HS (25.19 ± 7.00 vs. 30.45 ± 9.98 kgf in EU, P = 0.009) and functional capacity of the shoulder (41.28 ± 48.36 vs. 56.68 ± 37.44 s in EU, P = 0.004). The self-perception of fatigue by Chalder questionnaire (23.91 ± 5.39 vs. 29.77 ± 7.03, P = 0.000) and the QoL in terms of functional capacity (70.20 ± 21.57 vs. 56.25 ± 28.79, P = 0.025), physical aspects (71.42 ± 36.44 vs. 45.83 ± 42.88, P = 0.004), pain (62.48 ± 22.20 vs. 50.05 ± 24.80, P = 0.035), and emotional aspects (70.74 ± 38.26 vs. 46.29 ± 44.56, P = 0.008) were also worse in SCH. In conclusion, the SCH was associated with alterations in the QoL, reduction in the muscle function of upper limbs, and higher degree of fatigue.