Hoffmann’s Syndrome as a Rare Manifestation of Hypothyroidism: Current Views on Mechanisms of Development and Diagnosis

Hypothyroidism is one of the most common endocrine disorders, occurring in at least 5% of the population. The clinical picture of hypothyroidism is often non-specific, and the only complaints of the patient may include muscular symptoms such as stiffness, myalgias, cramps and rapid fatigue. Differential diagnosis in such cases is difficult, requiring the exclusion of many diseases. Meanwhile, late detection of hypothyroidism can lead to complications affecting almost all systems of the body, primarily cardiovascular and nervous. Regarding the musculoskeletal system, hypothyroidism is dangerous due to the risk of rhabdomyolysis, Hoffmann’s syndrome and myasthenia gravis. Although the pathogenesis of hypothyroid myopathy is not fully understood, the presumed mechanisms of muscle tissue destruction are based on a decrease in the oxidative capacity of mitochondria and abnormal glycogenolysis, leading to several metabolic dysfunctions. The clinical and biochemical evaluation of hypothyroid myopathy was based on twenty-four cases described in the English-­language literature from 1975 to 2024. All subjects studied had an elevation of serum creatine phosphokinase (CK). This elevation does not necessarily correlate with the severity of myopathic symptoms and does not explain the cause of the presumed muscle damage. The obligatory clinical manifestation is muscle weakness. Other common clinical manifestations included slowed tendon reflexes with a slow relaxation phase, myalgia, cramps and muscle induration in the absence of muscle hypertrophy and stiffness. Clinical presentation alone is not sufficient to diagnose hypothyroid myopathy, so serum TSH levels should be evaluated in all patients with muscle weakness or elevated CK levels.