Rhabdomyolysis and malignant hyperpyrexia.

detected in any patient by this method. Fourteen patients had raised serum creatine kinase activity (up to 5000 IU/1, normal range < 170 lU/i) and raised serum aspartate transaminase activity (up to 150 IU/1, normal < 35 IU/1). In all cases enzyme activity fell after admission to hospital. Peak serum creatine kinase activity was not significantly related to weight, sex, level of consciousness, or type of surface on which the patient was discovered. Five patients had spent less than six hours on the floor. They had significantly lower peak creatine kinase activity (p= <0-02; Mann-Whitney U test). All except one patient had aciduria (urine pH < 6). Serum creatinine concentration was raised on admission in seven patients but fell later. No patient gave a history of chest pain. Electrocardiographic changes suggestive of recent myocardial infarction were seen in only one. No patient had an abnormal cardiac scan, but in one focal skeletal muscle uptake was related to a site of pressure. Comment Raised serum myoglobin concentrations and creatine kinase and aspartate transaminase activities occurred in up to 84% of patients and were related to the period on the floor. Rises in serum muscle enzyme activity were considerable in some patients, with creatine kinase activity reaching 5000 IU/1, but despite long periods on the floor massive levels similar to those that occur when muscle injury is complicated by acute renal failure were not seen. Similarly, raised serum myoglobin concentrations were not very high. Why massive muscle injury occurs sporadically in conditions such as prolonged pressure or unusual exercise remains obscure. Although clearly the insult may be unusually severe, there is possibly a predisposition either extrinsically by an agent such as viral infection4 or intrinsically by an unrecognised abnormality of muscle metabolism." Myoglobinuria and clinically important renal injury did not occur at these low levels of myoglobinaemia despite most patients having aciduria and dehydration. Differentiation of myocardial from skeletal muscle injury is clinically important. Raised muscle enzyme activity after a collapse could easily indicate myocardial injury, which may be silent in old people. In our patients raised serum muscle enzyme activity was common' although myocardial injury was probable in only one. Raised serum muscle enzyme activity should therefore be interpreted with caution in diagnosing myocardial infarction in old people who are unable to get up after a fall. We thank Drs L WoUlner, R A Griffiths, and S T McCarthy for permission …