Lactic dehydrogenase isoenzymes in adolescents with multiple sclerosis.

Multiple sclerosis is an immune-mediated demyelinating disease with high morbidity and major mortality. To determine the potential use of lactic dehydrogenase activity and lactic dehydrogenase isoenzyme concentrations in cerebrospinal fluid as biomarkers of multiple sclerosis, we reviewed the files of all patients with multiple sclerosis who attended our tertiary pediatric medical facility from 1999-2005. The study group included three adolescent patients with multiple sclerosis (cerebrospinal fluid analysis at diagnosis) and one patient with recurrent optic neuritis (cerebrospinal fluid analysis during a disease episode). The isoenzyme pattern was abnormal in all patients with multiple sclerosis, with higher-than-normal levels of lactic dehydrogenase-2, lactic dehydrogenase-3, and lactic dehydrogenase-5 in two patients, and lower-than-normal levels of lactic dehydrogenase-4 in one patient. It was not necessarily, however, the same two patients who had the abnormally high levels of lactic dehydrogenase-2, -3, and -5. The patient with optic neuritis also exhibited an abnormal lactic dehydrogenase isoenzyme pattern that shared common features with the others. Multiple sclerosis appears to be characterized by an abnormal lactic dehydrogenase isoenzyme pattern in cerebrospinal fluid. The importance of this finding and its diagnostic potential use warrant further investigation.