Appendix: The Standardization of Growth Hormone Assays*
Consensus Statement From an International Collaborative
The availability of calibrants with different characteristics, the use of two units (mU/l and µg/l), adoption of a variety of unit conversion factors, and variability in antibody specificity are widely acknowledged as contributing to discrepancies between growth hormone (GH) results.[1,2] The discrepancies cause confusion and can have serious implications for the management of patients with GH-related disorders whose care is increasingly dependent on consensus guidelines employing mass concentration (NICE guidelines 2003).[3,4] The availability of the second International Standard (IS) for growth hormone (WHO IS 98/574), a recombinant material consisting of 22 kD growth hormone of > 95% purity, provides the opportunity for adoption of a single calibrant for growth hormone immunoassays.[5,6] IS 98/574's well-defined chemical and physical properties allows it to meet European Union legislation calls for all laboratory results to be traceable to a defined material (In Vitro Diagnostics Medical Devices Directive, 98/79/EC). As a first step to standardizing growth hormone measurement, we recommend the reporting of growth hormone concentrations in micrograms per litre (µg/l) of IS 98/574 (1 mg corresponding to 3 international units somatropin). A later step will be to reduce the discrepancy in results attributable to variable antibody specificity.
With effect from 1 September 2007, Clinical Endocrinology will only accept growth hormone data expressed in mass units of the International Standard for growth hormone WHO IS 98/574.
Collaborative Membership
The consensus statement represents the input of its members as follows:
Association for Clinical Biochemistry
130-32 Tooley Street
London
SE1 2TU
UK
British In Vitro Diagnostics Association
1 Queen Anne's Gate
London
SW1H 9BT
UK
DGKL
Referenzinstitut für Bioanalytik
Im Mühlenbach 52 a
D-53127 Bonn
Germany
Growth Hormone Research Society (GRS)
Medical Department M
Aarhus University Hospital
Nørrebrogade 44
DK-8000 Aarhus C
Denmark
National Institute for Biological Standards and Control
Blanche Lane
South Mimms
Potters Bar
Hertfordshire
EN6 3QG
UK
Randox International Quality Assessment Scheme
55 Diamond Road
Crumlin
Co. Antrim
BT29 4QY
UK
Royal College of Pathologists
2 Carlton House Terrace
London
SW1Y 5AF
UK
Society for Endocrinology
22 Apex Court
Woodlands
Bradley Stoke
Bristol
BS32 4JT
UK
UK National External Quality Assessment Service
PO Box 401
Sheffield
S5 7YZ
UK
We are grateful for the advice, guidance and support provided by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC). We are also grateful to the diagnostics industry for their support during the development of the consensus statement, as follows:
Beckman Coulter Inc
Clinical Diagnostics Division
1000 Lake Heseltine Dr
Chaska
MN 55318-1084
USA
BioSource Europe SA
Invitrogen Endocrinology Assays
Invitrogen Corporation
Rue de l'Industrie 8
B-1400 Nivelles
Belgium
PerkinElmer Life and Analytical Sciences/Wallac Oy
PO Box 10
FIN-20101
Turku
Finland
TOSOH Bioscience Inc
6000 Shoreline Court
Suite 101
South San Francisco
CA 94080
USA
* This statement is published in the journals Clinical Endocrinology, The European Journal of Endocrinology and Growth Hormone and IGF Research. Copyright remains with the authors.
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