Accessible Requires Authentication Published by De Gruyter August 11, 2015

Patient pools and the use of “patient means” are valuable tools in quality control illustrated by a bone-specific alkaline phosphatase assay

Maja Hinge, Erik D. Lund, Ivan Brandslund, Torben Plesner and Jonna S. Madsen


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.

Corresponding author: Jonna S. Madsen, Department of Clinical Immunology and Biochemistry, Lillebaelt Hospital, Kabbeltoft 25, 7100 Vejle, Denmark; and Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark, Phone: +45 79406501; E-mail:


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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Received: 2015-3-31
Accepted: 2015-7-8
Published Online: 2015-8-11
Published in Print: 2016-3-1

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