CPK: relationship of psychological and physical stress.

In the past few years, the finding of elevated serum levels of creatine phosphokinase in some acutely psychotic patients has commanded a great deal of interest. Although structural abnormalities in nerve and muscle of some of these patients have been described, the cause remains obscure. Physical stress will raise CPK, but the role of psychological stress has been unclear. CPK levels of medical students were measured before and after an academic examination, but no relationship between examination stress and changes in CPK was found. A significantly higher number of CPK elevations were reported in association with vigorous exercise. These findings are consistent with a hypothesis that psychological stress plays an insignificant role in the CPK elevations seen in some acutely psychotic patients. The importance of physical activity in elevated CPK values was reconfirmed.