THE ROLE OF CREATINE-KINASE IN THE DIAGNOSIS OF NEUROLEPTIC MALIGNANTSYNDROME

Elevation of serum creatine kinase (CK) concentrations occurs almost i nvariably in neuroleptic malignant syndrome (NMS). However, the role o f CK levels in the diagnosis of the syndrome remains controversial. Th is study measured CK levels in patients who became pyrexial while on p sychotropic medication and thereby mimicked some of the features of NM S. In all of these cases a diagnosis of infectious illness was made an d patients responded to appropriate antibiotic therapy without alterat ion in psychotropic medication. Two other groups were studied for comp arison - patients on psychotropics who were apyrexial and patients who became pyrexial but were not on psychotropics. Significant, unexpecte d elevations of CK were documented in 70 % of those patients who becam e pyrexial while on psychotropics - in three cases elevation of concen trations to more than 1000 IU/l (ten times reference value) were found . Thirty per cent of patients who became pyrexial but were not on psyc hotropics also developed elevation of CK but this was of a much smalle r magnitude (< 200 IU/l in five out of six cases). The results of the study suggest that elevation of CK is a non-specific finding, particul arly in patients who become pyrexial on psychotropics. Use of CK as a diagnostic criterion may lead to overdiagnosis of NMS.