Background: Quality control (QC) is an essential part of clinical biochemistry to ensure that laboratory test results are reliable and correct. Those tests without a defined reference method constitute a special challenge, as is the case with bone-specific alkaline phosphatase (BAP).
Methods and Results: The present study reports an example where a shift in a BAP assay was detected by use of a patient pool and supported by a retrospective calculation of “patient mean”, while the external QC and specific assay control material were unaffected by the shift.
Conclusions: Patient pools and the use of patient means remain a useful and inexpensive procedure for internal QC.
We would like to thank Liselotte Bjerregård Lauersen for her attentiveness in the laboratory work and for recognizing the steady increase in the results of BAP in the PP.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
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