Clinical Chemistry, Vol 19, 240-247, Copyright © 1973 by the American Association for Clinical Chemistry

Automated Kinetic Spectrophotometric Assays of Enzyme Activities of Human Cerebrospinal Fluid: Methods and Reference Values

¹ Departments of Chemical Pathology and Neurology, The Royal Hospital, West St., Sheffield S1 3SR, England.

Optimum conditions with respect to pH and molarity of phosphate buffer, and the concentrations of substrates, coenzymes, and exogenous enzyme, were defined at 37°C for activity of aspartate transaminase and lactate dehydrogenase of human cerebrospinal fluid (CSF), as measured by optical kinetic assays at 340 nm. The resulting methods, and a previously published procedure for malate dehydrogenase activity applicable to human CSF, were adapted for use with an automatic reaction-rate monitor. Within-batch and between-batch precision of all methods was satisfactory, and repeated estimations in seven subjects showed good agreement. Freezing samples decreased their activity by 5 to 10%, but thereafter no further losses occurred at -20°C for as long as three months. Injection of up to 12 ml of air during encephalography had no major effect. Reference values, derived from subjects with no neurological or simple chronic degenerative CNS disease, suggested that the upper limits (in U/liter) are: aspartate transaminase, 13.5; lactate dehydrogenase, 40; malate dehydrogenase, 58.

Accepted on November 22, 1972