MRCP2-2140
A recuperating alcoholic patient admitted to the ward has developed confusion after two days. Additionally, he complains of experiencing difficulty standing up from a sitting position and increasing shortness of breath. Upon further inquiry, it is discovered that he typically consumes 5-6 pints of medium strength lager daily, but his last drink was 7 days ago. He has a poor diet and smokes 30 rolled up cigarettes every day. During the examination, it is observed that his chest is clear, but he has generalised muscle weakness. What test is most likely to reveal the underlying abnormality?