Received on June 17, 2004
Accepted on September 28, 2004

Endocrinology and Metabolism

Establishment, Value Assignment, and Characterization of New WHO Reference Reagents for Six Molecular Forms of Human Chorionic Gonadotropin

¹ National Institute for Biological Standards and Control, Potters Bar, Herts, United Kingdom
² Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria
³ Department of Clinical Biology, Institut Gustave-Roussy, Villejuif, France
⁴ Department of Obstetrics and Gynecology, College of Physicians and Surgeons of Columbia University, New York, NY
⁵ Research Centre for Reproductive Health, Department of Obstetrics and Gynaecology, University of Adelaide, The Queen Elizabeth Hospital, Woodville, Australia
⁶ Department of Clinical Chemistry, Helsinki University Central Hospital, Finland
⁷ Department of Clinical Biochemistry, Royal Infirmary, Edinburgh, United Kingdom

^* To whom correspondence should be addressed. E-mail: C.Sturgeon{at}ed.ac.uk.

Background: The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) established a Working Group to investigate means of improving the comparability of immunoassays for human chorionic gonadotropin (hCG), which was selected as a prototype glycoprotein analyte. The Working Group identified development of unambiguous nomenclature and production of new highly purified International Reference Reagents calibrated in substance concentrations as its primary objectives.

Methods: Preparations of intact hCG, nicked hCG, hCG -subunit, nicked hCG -subunit, hCG -subunit, and hCG -core fragment were purified from a crude urinary hCG preparation, ampouled, lyophilized, and assigned values in substance concentrations (mol/L). Value assignment and accelerated degradation studies were carried out in accordance with WHO protocols for International Reference Reagents.

Results: The ampouled standards were assigned final values based on the recovery of immunoreactive material after reconstitution. The degradation studies showed that the standards were highly stable.

Conclusions: The nomenclature of hCG-related molecules and immunoassays has been adopted by the IFCC, and the standards prepared and characterized by the Working Group have been formally adopted by the WHO as the First International Reference Reagents for six hCG-related molecules. These developments will enable better understanding of what assays for hCG measure and should ultimate help to improve the clinical application of these assays.