Development of Reference Methods and Reference Materials for Clinical Diagnostic Markers

Summary

The accuracy of clinical diagnostic measurements is essential for reliable diagnosis and cost-effective treatment of disease. NIST's involvement in reference methods and reference materials to support accuracy in health-related measurements began more than forty years ago, and NIST is continually expanding the range of SRMs available. NIST works closely with the in-vitro diagnostic (IVD) community to identify and address reference material and methods needs, and to ensure that these SRMs are commutable with routine clinical assays. As part of this effort, new higher-order analytical methods have also been developed. These new reference methods and the associated SRMs provide critical traceability to the IVD industry and help improve the reliability of routine clinical measurements.

Description

Historical photograph of clinical Standard Reference Materials produced by NIST

Credit: NIST

Reference measurement procedures and standard reference materials help ensure accuracy and comparability of routine clinical assays. In addition, this work allows U.S. clinical diagnostic manufacturers to comply with the European Union directive regarding in-vitro diagnostic medical devices (IVD MD), which requires that values assigned to calibrators and control materials be traceable to reference materials and reference measurement procedures of a higher order. The Joint Committee for Traceability in Laboratory Medicine (JCTLM) maintains a listing of these higher-order reference materials and methods. The SRMs also support accuracy in measurements performed as part of the National Health and Nutrition Examination Survey (NHANES) that is conducted by CDC.

Major Accomplishments

• NIST now has over 30 SRMs available in the area of clinical diagnostics.   
• New reference measurement procedures have been developed for analytes of clinical diagnostic significance.    
• New SRMs have been developed in consultation with the IVD industry, the clinical chemistry community, and other government agencies.

Additional Technical Details

NIST continually updates its portfolio of SRMs for clinical diagnostics to meet the needs of the clinical chemistry community. Listed below are materials that are currently available. Early serum-based SRMs for clinical diagnostics were lyophilized materials. NIST is now moving toward fresh-frozen matrices because these materials are anticipated to have improved commutability with routine assays. SRM 955c Lead in Caprine Blood has been developed as a replacement for SRM 966 Toxic Elements in Bovine Blood. In addition to values for lead, this SRM includes values for inorganic and organic mercury species. New SRMs have also been developed for several vitamins in serum, including vitamin B₆ and D.

Many of the original reference measurement procedures for clinical analytes (formerly known as definitive methods) were based upon gas chromatography-mass spectrometry (GC/MS). These methods often required multi-step sample preparation as well as derivatization of the analyte of interest. More recently, liquid chromatography-mass spectrometry (LC/MS and LC-MS/MS) has been investigated as an alternative approach. Analyte derivatization is typically not required, and protein precipitation may be sufficient to release the analytes of interest. Both GC/MS and LC/MS methods were used to certify SRM 967 Creatinine in Human Serum, and the two techniques provided comparable results. The new LC/MS method is now listed as a higher-order method by the Joint Committee for Traceability in Laboratory Medicine (JCTLM).

Associated Product(s)

•  
• SRM 909c Human Serum - Routine clinical analytes 
• SRM 911c Cholesterol - Purity 
• SRM 912b Urea - Purity 
• SRM 913b Uric Acid - Purity 
• SRM 914b Creatinine - Purity 
• SRM 915c Calcium Carbonate   Mass fraction 
• SRM 917d D-Glucose - Purity 
• SRM 919b Sodium Chloride - Mass fraction 
• SRM 920 D-Mannitol - Purity 
• SRM 921a Cortisol (Hydrocortisone) - Purity 
• SRM 924a Lithium Carbonate - Purity 
• SRM 927f Bovine Serum Albumin (7 % Solution) (Total Protein Standard)  
• SRM 928 Lead Nitrate - Purity 
• SRM 929a Magnesium Gluconate - Magnesium 
• SRM 937 Iron Metal - Purity 
• SRM 955d Toxic Metals and Metabolites in Frozen Human Blood  
• SRM 965b Glucose in Frozen Human Serum - Glucose, four levels 
• SRM 967a Creatinine in Frozen Human Serum - Creatinine, two levels 
• SRM 968f Fat-Soluble Vitamins in Frozen Human Serum - Retinol, tocopherols, β-carotene, and cholesterol 
• SRM 971a Hormones in Frozen Human Serum - Cortisol, progesterone 
• SRM 972a Vitamin D Metabolites in Frozen Human Serum - Vitamin D metabolites, four levels 
• SRM 998 Angiotensin I - Purity 
• SRM 1400 Bone Ash - Elements 
• SRM 1486 Bone Meal - Elements 
• SRM 1595 Tripalmitin - Purity 
• SRM 1598a Inorganic Constituents in Animal Serum - Elements 
• SRM 1951c Lipids in Frozen Human Serum - Cholesterol, triglycerides 
• SRM 2389a Amino Acids in 0.1 mol/L Hydrochloric Acid  - Amino acids 
• SRM 2668 Toxic Elements in Frozen Human Urine 
• SRM 2921 Human Cardiac Troponin Complex - Cardiac troponin I 
• SRM 2973 Vitamin D Metabolites in Frozen Human Serum (High Level) – Vitamin D metabolites, one level 
• SRM 3667 Creatinine in Frozen Human Urine – Creatinine, one level 
• SRM 3950 Vitamin B6 in Frozen Human Serum – Vitamin B₆, two levels 

ASSOCIATED PUBLICATIONS

1. Camara, J. E., Pritchett, J. S., Daniels, Y. C., Bedner, M., Nelson, M. A., Lowenthal, M. S., Fazili, Z., Pfeiffer, C. M., Phinney, K. W., Sharpless, K. E., Sander, L. C., Lippa, K. A., Yen, J. H., Kuszak, A. J., and Wise, S. A., "Development of an improved standard reference material for folate vitamers in human serum," Analytical and Bioanalytical Chemistry, 415, 809-821 (2023).
2. Wise, S. A., "From urban dust and marine sediment to Ginkgo biloba and human serum-a top ten list of Standard Reference Materials (SRMs)," Analytical and Bioanalytical Chemistry, 414, 31-52 (2022).
3. Benner, B. A., Schantz, M. M., Powers, C. D., Schleicher, R. L., Camara, J. E., Sharpless, K. E., Yen, J. H., and Sniegoski, L. T., "Standard Reference Material (SRM) 2378 fatty acids in frozen human serum. Certification of a clinical SRM based on endogenous supplementation of polyunsaturated fatty acids," Analytical and Bioanalytical Chemistry, 410, 2321-2329 (2018).
4.  Tai, S.S., Nelson, M.A., Bedner, M., Lang, B.E., Phinney, K.W., Sander, L.C., Yen, J.H., Betz, J.M., Sempos, C.T., and Wise, S.A., “Development of Standard Reference Material (SRM) 2973 Vitamin D Metabolites in Frozen Human Serum (High Level),” J. AOAC Int., 100(5):1294-1303 (2017).
5. Phinney, K. W., Ballihaut, G., Bedner, M., Benford, B. S., Camara, J. E., Christopher, S. J., Davis, W. C., Dodder, N. G., Eppe, G., Lang, B. E., Long, S. E., Lowenthal, M. S., Mcgaw, E. A., Murphy, K. E., Nelson, B. C., Prendergast, J. L., Reiner, J. L., Rimmer, C. A., Sander, L. C., Schantz, M. M., Sharpless, K. E., Sniegoski, L. T., Tai, S. S. C., Thomas, J. B., Vetter, T. W., Welch, M. J., Wise, S. A., Wood, L. J., Guthrie, W. F., Hagwood, C. R., Leigh, S. D., Yen, J. H., Zhang, N. F., Chaudhary-Webb, M., Chen, H. P., Fazili, Z., Lavoie, D. J., Mccoy, L. F., Momin, S. S., Paladugula, N., Pendergrast, E. C., Pfeiffer, C. M., Powers, C. D., Rabinowitz, D., Rybak, M. E., Schleicher, R. L., Toombs, B. M. H., Xu, M., Zhang, M., and Castle, A. L., "Development of a Standard Reference Material for Metabolomics Research," Analytical Chemistry, 85, 11732-11738 (2013).
6. Simon-Manso, Y., Lowenthal, M. S., Kilpatrick, L. E., Sampson, M. L., Telu, K. H., Rudnick, P. A., Mallard, W. G., Bearden, D. W., Schock, T. B., Tchekhovskoi, D. V., Blonder, N., Yan, X. J., Liang, Y. X., Zheng, Y. F., Wallace, W. E., Neta, P., Phinney, K. W., Remaley, A. T., and Stein, S. E., "Metabolite Profiling of a NIST Standard Reference Material for Human Plasma (SRM 1950): GC-MS, LC-MS, NMR, and Clinical Laboratory Analyses, Libraries, and Web-Based Resources," Analytical Chemistry, 85, 11725-11731 (2013).
7. Yu, L. L., Davis, W. C., Ordonez, Y. N., and Long, S. E., "Fast and accurate determination of K, Ca, and Mg in human serum by sector field ICP-MS," Analytical and Bioanalytical Chemistry, 405, 8761-8768 (2013).
8. Thomas, J. B., Duewer, D. L., Mugenya, I. O., Phinney, K. W., Sander, L. C., Sharpless, K. E., Sniegoski, L. T., Tai, S. S., Welch, M. J., and Yen, J. H., "Preparation and value assignment of standard reference material 968e fat-soluble vitamins, carotenoids, and cholesterol in human serum," Analytical and Bioanalytical Chemistry, 402, 749-762 (2012).
9. Davis, W. C. and Long, S. E., "Measurements of methylmercury, ethylmercury, and inorganic mercury species in a whole blood standard reference material: SRM 955c-Toxic Elements in Caprine Blood," Journal of Analytical Atomic Spectrometry, 26, 431-435 (2011).
10. Tai, S. S. C., Bedner, M., and Phinney, K. W., "Development of a Candidate Reference Measurement Procedure for the Determination of 25-Hydroxyvitamin D-3 and 25-Hydroxyvitamin D-2 in Human Serum Using Isotope-Dilution Liquid Chromatography-Tandem Mass Spectrometry," Analytical Chemistry, 82, 1942-1948 (2010).
11. Murphy, K. E., Guthrie, W. F., Vetter, T. W., Turk, G. C., Palmer, C. D., Lewis, M. E., Geraghty, C. M., and Parsons, P. J., "Comparison of clinical methods with isotope dilution inductively coupled plasma mass spectrometry for the new standard reference material 955c lead in caprine blood," Journal of Analytical Atomic Spectrometry, 24, 1170-1178 (2009).
12. Nelson, B.C., Pfeiffer, C., Zhang, M., Duewer, D.L., Sharpless, K.E., and Lippa, K.A., "Commutability of NIST SRM 1955 Homocysteine and Folate in Frozen Human Serum with Selected Total Homocysteine Immunoassays and Enzymatic Assays," Clin. Chim. Acta, 395:99-105 (2008).Phinney, K.W., "Development of a Standard Reference Material for Vitamin D in Serum," Am. J. Clin. Nutr., 88(2):511S-512S, Suppl. S (2008).
13. Bunk, D.M., "Reference Materials and Reference Measurement Procedures: An Overview from a National Metrology Institute," Clin. Biochem. Rev., 28(4):131-137 (2007).
14. Dodder, N.G., Tai, S.S-C., Sniegoski, L.T., and Welch, M.J., "Certification of Creatinine in a Human Serum Reference Material by GC-MS and LC-MS," Clin. Chem., 53(9):1694-1699 (2007).
15. Murphy, K.E., Long, S.E., and Vocke, R.D., "On the Certification of Cadmium at Trace and Ultratrace Levels in Standard Reference Materials using ID ICP-MS," Anal. Bioanal. Chem., 387(7): 2453-2461 (2007).
16. Schantz, M.M., Keller, J.M., Leigh, S.D., Patterson, Jr., D.G., Sharpless, K.E., Sjödin, A., Stapleton, H.M., Swarthout, R., Turner, W.E., and Wise, S.A., "Certification of SRM 1589a PCBs, Pesticides, PBDEs, and Dioxins/Furans in Human Serum," Anal. Bioanal. Chem., 389(4):1201-1208 (2007).
17. Tai, S.S-C., Xu, B., Welch, M.J., and Phinney, K.W., "Development and Evaluation of a Candidate Reference Measurement Procedure for the Determination of Testosterone in Human Serum Using Isotope-Dilution Liquid Chromatography-Tandem Mass Spectrometry," Anal. Bioanal. Chem., 388(5-6):1087-1094 (2007).
18. Margolis, S. A., Vangel, M., and Duewer, D. L., "Certification of standard reference material 970, ascorbic acid in serum, and analysis of associated interlaboratory bias in the measurement process," Clinical Chemistry, 49, 463-469 (2003).
19. Long, S. E. and Vetter, T. W., "Determination of sodium in blood serum by inductively coupled plasma mass spectrometry," Journal of Analytical Atomic Spectrometry, 17, 1589-1594 (2002).
20. Phinney, C. S., Murphy, K. E., Welch, M. J., Ellerbe, P. M., Long, S. E., Pratt, K. W., Schiller, S. B., Sniegoski, L. T., Rearick, M. S., Vetter, T. W., and Vocke, R. D., "Definitive method certification of clinical analytes in lyophilized human serum: NIST standard reference material (SRM) 909b," Fresenius Journal of Analytical Chemistry, 361, 71-80 (1998).
21. Moody, J. R. and Vetter, T. W., "Development of the ion exchange-gravimetric method for sodium in serum as a definitive method," Journal of Research of the National Institute of Standards and Technology, 101, 155-164 (1996).