[Measurement of serum cholinesterase activity: comparison of commercial and laboratory test reagents, enzyme standards and statistical processing of the results].

The commercially available kits (Test-Combination, Cholinesterase, Boehringer, Mannheim and Test-reagent, Cholinesterase EC 3.1.1.8, Pliva, Zagreb) and reagents prepared in own laboratory for measuring cholinesterase activity (Ellman method) were tested with respect to their stability and the reproducibility of the activity measurements. The reagents of the three sources were shown to be interchangeable and equally stable over a few weeks. The coefficient of variation for within-run measurements by the Ellman method was 2-3% and that for between-run measurements 6%. The stability of the few enzyme standards (Precinorm E, Precinorm U, NBS-serum and native human serum) for the quality control of the measurements was also tested: the most stable was native human serum.