Quality Control of Radioimmunoassays for Proteins: The First Two and a Half Years of a National Scheme for Serum Growth Hormone Measurements

Abstract

All proposed participants were asked to complete a detailed questionnaire describing their assay procedure and were asked to accept the following conditions: level of accuracy, within-and between-laboratory precision, and response times achieved. An attempt was also made at rudimentary quality control of the laboratories' interpretative performance.Because it was hoped that the Scheme might lead to necessary and practicable steps to improve performance, strict anonymity was precluded. An entirely open system in which the identities and performance of individual laboratories were known to all seemed equally undesirable and likely to inhibit participation. The balance between these two extremes was struck by adopting a 'confidential' mode of operation in which the identity of the laboratories is known only to the organisers of the Scheme. Biochemistry, 1979, 16, 131-146 Quality control of radioimmunoassays for proteins: Annals of ClinicalThe first two and a half years of a national scheme for serum growth hormone measurements SUMMARY The philosophy and achievements of the first two and a half years of a national quality control scheme for serum growth hormone assays are described. Three serum samples were distributed to participating laboratories every two weeks. A computer-produced summary of the quality control results, which contained scattergrams and a statistical analysis, was returned to participants four weeks after despatch. The performance of 11 experienced (SAS) laboratories was found to fulfil the necessary accuracy criteria, and their results provided the 'reference group mean', which served as the target value. Gross positive bias exhibited by several laboratories was due to the use of assays with inadequate sensitivity, and this practice was eliminated during the first six months. During the course of the Scheme the average bias fell from 30 to 14 %. With assays of adequate sensitivity, bias was almost invariably due to the misuse of standards. Median within-laboratory, between-batch precision (CV) improved from 23 to 15 %. The best performers achieved between-batch CV of 7% which was 1·5 x their within-batch CV: the worst had three-to four-fold differences between withinand between-batch CV. Rudimentary quality control of interpretation was found to result in improvements in interpretation per se and also served to reinforce the desire to improve numerical agreement.A 'recommended procedure' based upon supplied first and second antibody, and a communal 'reference range' from 280 untreated acromegalies, both proved valuable.

Studies of a human growth hormone preparation used for clinical treatment in Great Britain

“…Radioimmunoassay of hGH This was the double-antibody procedure recommended to UK laboratories (Hunter & McKenzie, 1979); hGH antibody and anti-rabbit immunoglobulin-precipitating serum (donkey) were kindly provided by Dr W. M. Hunter, MRC Immunoassay Team, Edinburgh. The hGH standard was the World Health Organization 1st International Reference Preparation.…”