Final report on CCQM-K63.a,b: Non-peptide hormones in serum: cortisol and progesterone

Abstract

Hormones are chemical messengers that regulate many life functions. Deviations from normal hormone levels can have serious health consequences. Accurate measurement of hormone levels in serum can be beneficial in diagnosing, monitoring, and treating a number of diseases. Two steroid hormones, cortisol and progesterone, were selected by the Organic Analysis Working Group (OAWG) to evaluate its member Institutes' measurement capabilities for this important class of measurand.Serum concentrations of cortisol range from 30 ng/mL to 230 ng/mL. Serum concentrations of progesterone in adult females range from 0.15 ng/mL to 25 ng/mL but can rise to ≈230 ng/mL during pregnancy. The ability to measure cortisol is indicative of a laboratory's ability to measure steroid hormones at concentration levels similar to cortisol. The ability to measure progesterone is indicative of a laboratory's ability to measure steroid hormones with similar functional groups and concentration levels, such as testosterone.Pilot studies CCQM-P77.a and CCQM-P77.b on the determination of cortisol and progesterone in human serum were completed in 2006. There was good agreement among the results reported by participants who used isotope dilution/mass spectrometry (ID/MS) with either gas chromatography (GC) or liquid chromatography (LC). In 2007 the OAWG decided to proceed with key comparison (KC) CCQM-K63.a, cortisol in human serum, and CCQM-K63.b, progesterone in human serum. Thus, following established OAWG procedure, only results from participants that (1) used an ID/MS-based method, (2) participated in the relevant pilot study, and (3) used a metrologically traceable primary standard were to be eligible for use in calculating the key comparison reference value (KCRV) for each measurand.Six laboratories participated in CCQM-K63.a and eight laboratories participated in CCQM-K63.b. The same pooled frozen female serum material was used in both of the KCs. The mean value for the six ID/MS-based cortisol results is 100.4 ng/g with a relative standard deviation (%RSD) of 1.1%. The mean value for the seven ID/MS-based progesterone originally reported results is 2.83 with a %RSD of 1.8%. While a number of the reported results were not eligible to be used in establishing the KCRVs, the KCRVs as estimated from just the eligible results agree very well with these means. The excellent among-participant agreement indicates that ID/MS-based measurement procedures can provide precise and true results for steroid hormones at levels greater than about 1 ng/g. The progesterone result reported by a laboratory using a non-isotopically labelled internal standard was about 11% larger than the KCRV.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).