Testosterone has been reported to cause or is associated with a wide range of diseases and disorders, such as, polycystic ovary syndrome, metabolic syndrome, diabetes, cardiovascular disease, and mortality. Measurements of circulating testosterone concentrations are widely used in both research and patient care to assess diseases state, disease risk and monitor therapy. However, problems in the performance of these measurements, with regards to test accuracy, precision, specificity and sensitivity were reported, even in MS based assays. This situation greatly limits the advancement of research and use of measurements in patient care and disease prevention.
The need for standardization of testosterone measurements to overcome these limitations has been stated by the clinical and research communities. The Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention (CDC) responded to this need by starting a project to standardize steroid hormone testing and improve the use of these tests. The aim of this effort is to harmonize laboratories to assure accurate and comparable measurements regardless of the method, the measurement procedure, and of the laboratory where the analyses are carried out.
The most important strategy to achieve standardization is the concept of measurement traceability. Key components in the establishment of metrological traceability are higher-order materials and reference procedures. The CDC has established both for total testosterone measurements using ID-LC-MS/MS technology. This established reference measurement system provides metrological traceability to routine clinical analysis by linking the patient’s laboratory measurement results to an established higher-order standard through an unbroken chain of comparisons.
The CDC Testosterone Standardization Effort is providing program participants with matrix-based “secondary” reference materials in the form of non-pooled sera from single donors obtained following the protocol from the Clinical and Laboratory Standards Institute (CLSI) C37-A “Preparation and Validation of Commutable Frozen Human Serum”. Sera prepared according to this protocol have been shown commutable in previous studies and were recommended for use in trueness control and calibration studies. Values obtained from participants are used for bias assessment as described in CLSI guideline EP9-A2 “Method comparison and Bias Estimation using Patient Samples” and for establishing traceability and standardization to the CDC laboratory. The acceptable bias is based on the data published by Westgard (www.Westgard.com). According to this source the desirable bias is 6.4% and the imprecision is 4.7%.
The CDC Testosterone Standardization Effort is working towards providing accurate and reliable results for optimal patient care. |
|
