Serum creatine phosphokinase in epidemic influenza

Creatine phosphokinase (CPK) in serum was determined in the acute stage of 22 patients confined to bed with epidemic influenza and in the covalescence. Further, 21 healthy controls were investigated during bed rest and when ambulant. The activities of CPK were higher in the acute stage of influenza than during the convalescence out of bed, whilst the controls showed higher activities when ambulant than during bed rest. The findings are compatible with involvement of striated muscle in epidemic influenza.