Isokinetic evaluation of muscle strength in patients with thyroid dysfunction

Skeletal muscle weakness is a frequent symptom of thyroid dysfunction. Both hypothyroidism and hyperthyroidism may cause signs and symptoms of neuromuscular dysfunction. It has been reported in previous studies that muscle strength recovers after treatment of thyroid dysfunction. The aim of the current study was to evaluate knee extensors and flexors strength in patients with thyroid dysfunction before and after medical treatment and compare the data with those of a matched control group. For this purpose 11 hyperthyroid, 9 hypothyroid patients and 27 healthy controls were recruited. All were tested isokinetically on the dominant side. The results suggest that return of thyroid hormone concentrations to their reference ranges, significantly increases muscular strength in hyperthyroid patients. However there was no significant recovery in the hypothyroid group. Nevertheless in both groups post-treatment muscle strength was significantly lower than in the control group. The findings suggest that patients with thyroid dysfunction, especially with hypothyroidism, should train for muscle strengthening after establishing euthyroidism to obtain optimum life conditions.