WHO has established a reference preparation for hCG (currently the fourth International Standard, with an assigned content of 650 IU/ampoule) and a reference preparation for hCG-beta (currently the first WHO Reference Reagent for immunoassay of hCG beta subunit, with an assigned content of 0.88nmol/ampoule)
650 IU/ampoule
0.88nmol/ampoule
The former preparation was assigned a value based on bioassay, whereas the latter preparation had been extensively characterized by physicochemical and immunological methods and calibrated in nanomol by amino acid analysis.
If I understood correctly based on the 0.88nmol they have determined the 650 IU
What bioassay have they done to derive 650 IU/ampoule? an example will be good.
250 micrograms (μg) of r-hCG represent 6.8 nmols/liter and should equate to approximately 2,325 IU of bioactivity.
How is the bioactivity experiment designed or steps of how its done?
Say I have 100 μg/ml of r-hCG and I need to express it in IU/ml, steps for conversion or experiment design for clinical evaluation?
International reference reagents for the most important forms of hCG, intact biologically active heterodimeric hCG (hCG), nicked hCG (hCGn), free alpha-subunit of hCG, free beta-subunit of hCG, nicked free beta-subunit of hCG (hCGbn), and hCG beta-subunit core fragment (hCGbcf), have been formulated. These standards were established by a working group of the International Federation of Clinical Chemistry (IFCC) and are available from the World Health Organization (WHO) .
-- Preparation and characterization of new WHO reference reagents for human chorionic gonadotropin and metabolites.AUBirken S, Berger P, Bidart JM, Weber M, Bristow A, Norman R, Sturgeon C, Stenman UH SOClin Chem. 2003;49(1):144.
The hCG hormone is measured in milli-international units per milliliter (mIU/mL).
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