Correct!
4. 1 and 3
The markedly reduced MIP suggests neuromuscular disease (3). The shape of our patient’s flow-volume loop is relatively normal. A “rounded” expiratory peak has been described with neuromuscular disease but this appears to be neither sensitive or specific (3).
A repeat troponin (since he had a previous elevation), creatinine kinase and an AChRAb should be ordered as screening tests for some neuromuscular diseases. The troponin came back elevated at about 600 ng/mL but did not change over time. Creatinine kinase, an enzyme released into the blood stream with myositis, was normal. However, the AChRAb was markedly elevated at 18.0 mmol/L (normal < 0.02). This led to a presumptive diagnosis on myasthenia gravis which was confirmed by a positive AChR modulating flow cytometry and electromyography (EMG).
What medication is the patient taking which likely led to unmasking his myasthenia gravis? (Click on the correct answer to be directed to the fifth of six pages).