engleski

Interlaboratory study of the proficiency of cholinesterase activity measurements and attribution of genotypes

The correct identification of variants of butyrylcholinesterase (EC 3.1.1.8) in human serum is essential to individuate patients who experience sensitivity to short-acting muscle relaxants (succinyl dicholine and related compounds) and to counsel them and their relatives. Furthermore, accurate measurement of serum butyrylcholinesterase activity is important because the enzyme is a target enzyme in organophosphate poisoning. In order to assess the ability of clinical laboratories to identify enzyme genotype and to measure activity, the Cholinesterase proficiency programme was organised by Cholinesterase Investigation Unit (Head: Dr. R. T. Evans) of St. James’s University Hospital, Leeds, UK. The project ran from January 1993 until August 1998. Thirty one laboratories from the United Kingdom, Canada, Croatia, and New Zealand originally expressed a wish to join the programme. Before entering the programme all potential participants were required to complete a questionnaire. It established the analytical procedures for butyrylcholinesterase activity measurements employed by laboratories and the frequency at which the assay used to be performed. At the beginning of each year, a timetable was circulated setting the dates of the distribution of specimens and the return dates for analytical findings and their interpretation. The timetable also set the expected date of cumulative reports issued by the organiser. Results not returned by the specified date were excluded from consideration. Specimens were sent out at intervals of approximately six weeks. They were taken from selected patients who had previously been investigated in the parent laboratory. They had a variety of genotypes, only some of which are associated with sensitivity to succinyl dicholine. Of the 983 reports which were returned, 837 (85.1%) were correct in the ascription of genotype, 108 (11%) were incorrect, and 38 (3.9%) did not attribute the genotype usually due to an inability to interpret the analytical findings. In the second part of the project an improvement in performance was achieved by the participating laboratories ; the number of correct ascriptions increased and the number of analysed samples lacking any ascription to a genotype was reduced to one third of the previous.

butyrylcholinesterase activity; genotype; phenotype; quality control

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