[Hypothyroidism with leading myopathy in a patient suffering from systemic lupus erythematosus and Hashimoto's thyroiditis].

BACKGROUND

Muscle weakness with or without elevation of serum creatine kinase (CK) is a common complaint, which is a diagnostic challenge for the treating physician. Either infectious, neurologic, iatrogenic, genetic or endocrinologic and rheumatologic causes should be considered.

CASE REPORT

A 66-year-old female patient with a history of systemic lupus erythematosus (SLE) currently in remission presented herself with muscle weakness, myalgias and elevated CK (1618 U/l) to the authors' hospital. A flare of the SLE as cause of the symptoms could be ruled out diagnostically. Instead, a Hashimoto's-associated hypothyroidism was detected. Treatment with L-thyroxine resulted in rapid improvement of symptoms, and CK levels returned to normal.

CONCLUSION

Although a myositis can be observed in SLE patients suffering from muscle weakness with elevated CK levels, a careful evaluation is warranted. In the presented case, hypothyroidism due to Hashimoto's thyroiditis was the real culprit of the symptoms.