A 61-Year-Old Woman with Muscle Fatigue and Increased Cardiac Troponin

[摘要] A 61-year-old woman presented with a 12-month history of progressive muscle weakness, especially involving the proximal limb muscles. Her symptoms were associated with muscular fatigue such that she was compelled to sit and rest after walking only 30–50 m. She reported difficulty climbing stairs and standing from a sitting position. There was no rash or Raynaud phenomenon but she did report some episodes of feeling hot and perspiring. She denied any paresthesia, headache, or chest pain. Her past history included sigmoid diverticular disease, osteoarthritis of the cervical spine, and depression for over 20 years with psychotic features in the last 2–3 years. Her medications were aripiprazole 5 mg daily, irbesartan 150 mg daily, amisulpride 150 mg daily, imipramine 50 mg nocte, lercanidipine 10 mg daily, and sertraline 300 mg daily. She had also recently started replacement therapies for B12 and vitamin D deficiencies. Salient examination findings included a general reduction in muscle power, proximal greater than distal, with intact reflexes and sensation.Initial investigation included an erythrocyte sedimentation rate of 32 mm/h [reference interval (RI) <20], creatine kinase (CK)4 activity of 1900 U/L (RI <140), negative screen for antinuclear and extractable nuclear antigen antibodies, and a negative myositis autoantibody panel. The patient was biochemically euthyroid [thyroid stimulating hormone 1.95 mU/L (RI 0.1–5.0)] and had no evidence of renal dysfunction, with creatinine of 0.75 mg/dL [66 μmol/L; RI 0.51–1.02 mg/dL (45–90 μmol/L)]. MRI of the right thigh did not show features of myositis. The patient was admitted to the hospital for a trial withdrawal of her antipsychotic medication but after 5 days there was no change in her condition. CK remained increased at 510 U/L with a CK-MB fraction of 11.8% (RI <4%). Cardiac troponin T (cTnT) was 83 ng/L (99th percentile <14) measured using the high-sensitivity cTnT (hs-cTnT) assay …

[学科分类] 过敏症与临床免疫学