Analytical and Bioanalytical Chemistry

, Volume 397, Issue 2, pp 521–525 | Cite as

Standardization of ceruloplasmin measurements is still an issue despite the availability of a common reference material

  • Ilenia Infusino
  • Cristina Valente
  • Alberto Dolci
  • Mauro Panteghini
Technical Note


The purpose of measurement standardization is to achieve closer comparability of results obtained using different commercial systems. Regarding serum protein immunoassays, a reference preparation (BCR-470) was released in 1993 and adopted by manufacturers across the world to value-assign their assay calibrators for routine methods to reduce method-dependent variation. Moving from nephelometric (Beckman Immage 800) to turbidimetric determination (Roche Cobas c 501) of seven serum proteins, we preliminarily checked the comparability of results between the two systems. The study was performed according to the CLSI EP9-A protocol on 30 fresh sera, tested on each system in duplicate, and subdivided on two different days, without recalibration and using manufacturers’ control materials to validate the runs. Both manufacturers’ package inserts provide statements that kit calibrators are traceable to BCR-470. Suggested reference intervals are also the same. Although a fairly good correlation was observed (r = 0.955), the comparison of ceruloplasmin methods produced evidence of highly significant proportional (regression slope, 0.572) and constant bias (intercept, 0.05 g/L). Absolute and percentage mean differences were −0.11 g/L (95% confidence interval (CI) −0.13 to −0.10 g/L) and −39.1% (CI −43.1 to −35.2%), respectively. No other evaluated proteins showed similar problems. Lacking a ceruloplasmin reference method, it is impossible to demonstrate that one of the two assays produces true ceruloplasmin values. The problem is, however, that results coming from the two assays are clearly not comparable. This may be either due to a lack of commutability of the reference material with biological samples in the evaluated assays or to calibration problems by manufacturers in one of the stages of the calibration hierarchy.


Ceruloplasmin Nephelometry Immunologic techniques Standardization Reference materials Biological samples 


  1. 1.
    Panteghini M, Forest JC (2005) Standardization in laboratory medicine: new challenges. Clin Chim Acta 355:1–12CrossRefGoogle Scholar
  2. 2.
    Panteghini M (2007) Traceability, reference systems and result comparability. Clin Biochem Rev 28:97–104Google Scholar
  3. 3.
    Panteghini M (2009) Traceability as a unique tool to improve standardization in laboratory medicine. Clin Biochem 42:236–240CrossRefGoogle Scholar
  4. 4.
    ISO 15194 (2002) In vitro diagnostic systems—measurement of quantities in samples of biological origin—description of reference materials. ISO, GenevaGoogle Scholar
  5. 5.
    Miller WG, Myers GL, Rej R (2006) Why commutability matters. Clin Chem 52:553–554CrossRefGoogle Scholar
  6. 6.
    Vesper HW, Miller WG, Myers GL (2007) Reference materials and commutability. Clin Biochem Rev 28:139–147Google Scholar
  7. 7.
    Johnson AM (1993) A new international reference preparation for proteins in human serum (RPPHS). Arch Pathol Lab Med 117:29–31Google Scholar
  8. 8.
    Whicher J, Ritchie RF, Johnson AM, Baudner S, Bienvenu J, Blirup-Jensen S, Carlstrom A, Dati F, Ward AM, Svendsen PJ (1994) New international reference preparation for proteins in human serum (RPPHS). Clin Chem 40:934–938Google Scholar
  9. 9.
    Johnson AM, Whicher JT, Ledue TB, Carlström A, Itoh Y, Petersen PH (2000) Effect of a new international reference preparation for proteins in human serum (certified reference material 470) on results of the College of American Pathologists survey for plasma proteins. Arch Pathol Lab Med 124:1496–1501Google Scholar
  10. 10.
    Johnson AM, Whicher JT (2001) Effect of certified reference material 470 (CRM 470) on national quality assurance programs for serum proteins in Europe. Clin Chem Lab Med 39:1123–1128CrossRefGoogle Scholar
  11. 11.
    NCCLS (1995) Method comparison and bias estimation using patient samples; Approved guideline. NCCLS document EP9-A. NCCLS, Wayne, PAGoogle Scholar
  12. 12.
    Desirable specifications for total error, imprecision, and bias, derived from biologic variation. Accessed July 14, 2009
  13. 13.
    Fraser CG, Petersen PH, Libeer JC, Ricos C (1997) Proposals for setting generally applicable quality goals solely based on biology. Ann Clin Biochem 34:8–12Google Scholar
  14. 14.
    Ferrarotti M, Gorrini M, Scabini R, Luisetti M (2009) Laboratory diagnosis for inherited α1-antitrypsin deficiency. Biochim Clin 33:39–44Google Scholar
  15. 15.
    Mak CM, Lam CW, Tam S (2008) Diagnostic accuracy of serum ceruloplasmin in Wilson disease: determination of sensitivity and specificity by ROC curve analysis among ATP7B-genotyped subjects. Clin Chem 54:1356–1362CrossRefGoogle Scholar
  16. 16.
    Mak CM, Lam CW (2008) Diagnosis of Wilson’s disease: a comprehensive review. Crit Rev Clin Lab Sci 45:263–290CrossRefGoogle Scholar
  17. 17.
    Beetham R, White P, Riches P, Bullock D, MacKenzie F, for UK NEQAS Protein Assays Specialist Advisory Group (2002) Use of CRM 470/RPPHS has not achieved true consensus for ceruloplasmin measurement. Clin Chem 48:2293–2294Google Scholar
  18. 18.
    Buffone GJ, Brett EM, Lewis SA, Iosefsohn M, Hicks JM (1979) Limitations of immunochemical measurement of ceruloplasmin. Clin Chem 25:749–751Google Scholar
  19. 19.
    Dati F, Johnson MJ, Whicher JT (2001) The existing interim consensus reference ranges and the future approach. Clin Chem Lab Med 39:1134–1136CrossRefGoogle Scholar
  20. 20.
    Blirup-Jensen S, Johnson AM, Larsen M, on behalf of the IFCC Committee on Plasma Proteins (2008) Protein standardization V: value transfer. A practical protocol for the assignment of serum protein values from a reference material to a target material. Clin Chem Lab Med 46:1470–1479CrossRefGoogle Scholar
  21. 21.
    Kimberly MM, Caudill SP, Vesper HW, Monsell EA, Miller WG, Rej R, Rifai N, Dati F, Myers GL (2009) Standardization of high-sensitivity immunoassays for measurement of C-reactive protein; II: two approaches for assessing commutability of a reference material. Clin Chem 55:342–350CrossRefGoogle Scholar
  22. 22.
    BIPM. Accessed September 14, 2009
  23. 23.
    Zegers I, Munoz A, Trapmann S, Emons H, Schimmel H. Production of the serum protein reference material ERM-DA470k/IFCC. The 12th Biological and Environmental Reference Material Symposium (BERM12), 7–10 July 2009, Oxford, UK. Scientific programme and abstracts: 89Google Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Ilenia Infusino
    • 1
    • 2
    • 3
  • Cristina Valente
    • 2
  • Alberto Dolci
    • 2
  • Mauro Panteghini
    • 1
    • 2
  1. 1.Centre for Metrological Traceability in Laboratory Medicine (CIRME)University of MilanMilanItaly
  2. 2.Clinical Biochemistry Laboratory‘Luigi Sacco’ University HospitalMilanItaly
  3. 3.Laboratorio Analisi, Ospedale L. SaccoMilanItaly

Personalised recommendations