WHO/BS/2014.2240 WHO International Collaborative Study of the proposed 1st IS for Human, Pituitary Luteinizing Hormone

Overview

The World Health Organization (WHO) Expert Committee on Biological Standardization (ECBS) has recognized (2011) the need for a replacement International Standard (IS) for human, pituitary luteinizing hormone (LH) for the calibration of immunoassays to measure LH in human serum and plasma. We report here, the calibration of a candidate standard for human pituitary LH by immunoassay in terms of the current, 2nd IS for human, pituitary LH, coded 80/552, by an International Collaborative Study carried out by eleven laboratories in seven countries. The unweighted geometric mean of the laboratory estimates of the LH immunoreactivity of the candidate standard, coded 81/535, is 33.2 IU per ampoule (95% confidence limits 32.1 – 34.3). The results of this study also indicate that the candidate standard appears sufficiently stable, on the basis of a thermally accelerated degradation study, to serve as an IS. The study included a partial assessment of the impact of the new standard on the routine measurement of LH in human serum samples. All laboratories contributed data during the Collaborative Study through the concomitant measurement by immunoassay of 12 human serum samples. The results suggest that the candidate standard is suitable for the continued calibration of immunoassay methods for the measurement of LH. Therefore, it is proposed that the candidate preparation in ampoules coded, 81/535 is established as the 3rd IS for human, pituitary LH for immunoassay with an assigned content of 33 IU LH per ampoule.