Hypothyroid Myopathy with Muscle Pseudohypertrophy

A 35-year-old man with progressive limb weakness, intermittent muscle cramping, fatigue, weight gain, and constipation was diagnosed with hypothyroid myopathy with muscle pseudohypertrophy (Hoffman’s syndrome), caused by severe hypothyroidism due to Hashimoto's thyroiditis.

Physical examination revealed macroglossia and calf muscle enlargement, along with proximal muscle weakness and delayed deep-tendon reflexes. Laboratory tests confirmed hypothyroidism, with markedly elevated thyrotropin and thyroid peroxidase antibody levels, along with severe muscle damage (creatine kinase level: 7087 U/L).

Muscle pseudohypertrophy in hypothyroidism results from altered muscle-fiber composition and glycosaminoglycan accumulation in muscle tissue. The patient was treated with levothyroxine, which led to complete resolution of muscle weakness, though pseudohypertrophy persisted at the three-month follow-up.

A 35-year-old man with progressive limb weakness, intermittent muscle cramping, fatigue, weight gain, and constipation was diagnosed with hypothyroid myopathy with muscle pseudohypertrophy (Hoffman’s syndrome), caused by severe hypothyroidism due to Hashimoto's thyroiditis.

Physical examination revealed macroglossia and calf muscle enlargement, along with proximal muscle weakness and delayed deep-tendon reflexes. Laboratory tests confirmed hypothyroidism, with markedly elevated thyrotropin and thyroid peroxidase antibody levels, along with severe muscle damage (creatine kinase level: 7087 U/L).

Muscle pseudohypertrophy in hypothyroidism results from altered muscle-fiber composition and glycosaminoglycan accumulation in muscle tissue. The patient was treated with levothyroxine, which led to complete resolution of muscle weakness, though pseudohypertrophy persisted at the three-month follow-up.