In a trial of the Netherlands coupled external/internal quality control program a control serum and an enzyme standard were analysed over a period of eight weeks, five times each week. Five enzymes were determined: alkaline phosphatase, creatine kinase, lactate dehydrogenase, alanine aminotransferase, and γ-glutamyltransferase. The measured values in the serum were converted to the standards. Those laboratories using the recommended methods also submitted their non-transformed serum values. The following standardisation techniques have been compared: (a) no standardisation of methodology but use of enzyme standards; (b) standardisation of methodology; (c) standardisation of methodology combined with use of an enzyme standard. Results were submitted to analysis of variance. Standardisation of methodology did not yield smaller interlaboratory variation than the standardisation with enzyme standards. In this trial a combination of both standardisation techniques yielded generally better results. Results for γ-glutamyltransferase indicate that standardisation of substrate may be necessary apart from the use of an enzyme standard. The preparation of stable enzyme standards is stressed.
[1]
A. Vassault,et al.
Criteria for establishing a standardized method for determining alkaline phosphatase activity in human serum.
,
1977,
Clinical chemistry.
[2]
Batsakis Jg,et al.
The 1978 College of American Pathologists survey of analyses of five serum enzymes by 450 laboratories.
,
1979
.
[3]
R. Jansen,et al.
A coupled external/internal quality control program for clinical laboratories in the Netherlands.
,
1980,
Clinica chimica acta; international journal of clinical chemistry.
[4]
C. Burtis,et al.
An interlaboratory study of measurement of aspartate aminotransferase activity with use of purified enzyme materials.
,
1978,
Clinical chemistry.
[5]
B. Leijnse,et al.
Experience in the Netherlands with an external quality control and scoring system for clinical chemistry laboratories.
,
1977,
Clinica chimica acta; international journal of clinical chemistry.
[6]
Recommended method for the determination of creatine kinase in blood.
,
1976,
Scandinavian journal of clinical and laboratory investigation.