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Routine serum creatinine measurements: how well do we perform?

Hoste L, Deiteren K, Pottel H, Callewaert N, Martens F - BMC Nephrol (2015)

Bottom Line: The calculated eGFR values corresponding with the reported creatinine concentration ranges resulted in a different CKD classification in 47% of cases.The inaccuracy in the lower concentration range is of particular concern and may lead to clinical misinterpretation when the creatinine-based eGFR of the patient is used for CKD staging.Further research to improve harmonization between methods is required.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Research Facility Life Sciences, Katholieke Universiteit Leuven Campus Kortrijk, Kortrijk, Belgium. liesbeth.hoste@kuleuven-kulak.be.

ABSTRACT

Background: The first aim of the study was to investigate the accuracy and intra-laboratory variation of serum creatinine measurements in clinical laboratories in Flanders. The second purpose was to check the effect of this variation in serum creatinine concentration results on the calculated estimated glomerular filtration rate (eGFR) and the impact on classification of patients into a chronic kidney disease (CKD) stage.

Methods: 26 routine instruments were included, representing 13 different types of analyzers from 6 manufacturers and covering all current methodologies (Jaffe, compensated Jaffe, enzymatic liquid and dry chemistry methods). Target values of five serum pools (creatinine concentrations ranging from 35 to 934 μmol/L) were assigned by the gold standard method (ID-GC/MS).

Results: Intra-run CV (%) (n = 5) and bias (%) from the target values were higher for low creatinine concentrations. Especially Jaffe and enzymatic dry chemistry methods showed a higher error. The calculated eGFR values corresponding with the reported creatinine concentration ranges resulted in a different CKD classification in 47% of cases.

Conclusions: Although most creatinine assays claim to be traceable to the gold standard (ID-GC/MS), large inter-assay differences still exist. The inaccuracy in the lower concentration range is of particular concern and may lead to clinical misinterpretation when the creatinine-based eGFR of the patient is used for CKD staging. Further research to improve harmonization between methods is required.

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Related in: MedlinePlus

Error calculations based on CViand bias. Ricos-Fraser total error goals are presented. Solid horizontal line: minimal (<13.3%). Dashed horizontal line: desirable (<8.9%). Dotted horizontal line: optimal (<4.5%).
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Fig3: Error calculations based on CViand bias. Ricos-Fraser total error goals are presented. Solid horizontal line: minimal (<13.3%). Dashed horizontal line: desirable (<8.9%). Dotted horizontal line: optimal (<4.5%).

Mentions: An error based on CVi and bias (inter-run CV not taken into account) was calculated and compared with the Ricos-Fraser TE (Figure 3). Inter-run experiments were not performed so the actual TEs would presumably be higher than these ‘intermediate’ calculated errors. The calculated errors were compared with the minimal (<13.3%, solid line), desirable (<8.9%, dashed line) and optimal (<4.5%, dotted line) Ricos-Fraser TE categories. Concerning pool 1, the acceptable error (13.3%) was already exceeded for 5 out of 7 Jaffe, for 3 out of 7 compensated Jaffe and for all three dry chemistry analyzers. Extreme errors were calculated for the two Architect C1600 analyzers (Jaffe) (29.2% and 31.7%) and for the Dimension Vista 1500 (Jaffe) (50.7%). For pool 2 the Dimension Vista 1500 (Jaffe) and one Integra 800 (compensated Jaffe) showed insufficient results when compared with the Ricos-Fraser TE criteria. The error calculations for pool 3–5 all fell within the TE budget of Ricos-Fraser.Figure 3


Routine serum creatinine measurements: how well do we perform?

Hoste L, Deiteren K, Pottel H, Callewaert N, Martens F - BMC Nephrol (2015)

Error calculations based on CViand bias. Ricos-Fraser total error goals are presented. Solid horizontal line: minimal (<13.3%). Dashed horizontal line: desirable (<8.9%). Dotted horizontal line: optimal (<4.5%).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4358903&req=5

Fig3: Error calculations based on CViand bias. Ricos-Fraser total error goals are presented. Solid horizontal line: minimal (<13.3%). Dashed horizontal line: desirable (<8.9%). Dotted horizontal line: optimal (<4.5%).
Mentions: An error based on CVi and bias (inter-run CV not taken into account) was calculated and compared with the Ricos-Fraser TE (Figure 3). Inter-run experiments were not performed so the actual TEs would presumably be higher than these ‘intermediate’ calculated errors. The calculated errors were compared with the minimal (<13.3%, solid line), desirable (<8.9%, dashed line) and optimal (<4.5%, dotted line) Ricos-Fraser TE categories. Concerning pool 1, the acceptable error (13.3%) was already exceeded for 5 out of 7 Jaffe, for 3 out of 7 compensated Jaffe and for all three dry chemistry analyzers. Extreme errors were calculated for the two Architect C1600 analyzers (Jaffe) (29.2% and 31.7%) and for the Dimension Vista 1500 (Jaffe) (50.7%). For pool 2 the Dimension Vista 1500 (Jaffe) and one Integra 800 (compensated Jaffe) showed insufficient results when compared with the Ricos-Fraser TE criteria. The error calculations for pool 3–5 all fell within the TE budget of Ricos-Fraser.Figure 3

Bottom Line: The calculated eGFR values corresponding with the reported creatinine concentration ranges resulted in a different CKD classification in 47% of cases.The inaccuracy in the lower concentration range is of particular concern and may lead to clinical misinterpretation when the creatinine-based eGFR of the patient is used for CKD staging.Further research to improve harmonization between methods is required.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Research Facility Life Sciences, Katholieke Universiteit Leuven Campus Kortrijk, Kortrijk, Belgium. liesbeth.hoste@kuleuven-kulak.be.

ABSTRACT

Background: The first aim of the study was to investigate the accuracy and intra-laboratory variation of serum creatinine measurements in clinical laboratories in Flanders. The second purpose was to check the effect of this variation in serum creatinine concentration results on the calculated estimated glomerular filtration rate (eGFR) and the impact on classification of patients into a chronic kidney disease (CKD) stage.

Methods: 26 routine instruments were included, representing 13 different types of analyzers from 6 manufacturers and covering all current methodologies (Jaffe, compensated Jaffe, enzymatic liquid and dry chemistry methods). Target values of five serum pools (creatinine concentrations ranging from 35 to 934 μmol/L) were assigned by the gold standard method (ID-GC/MS).

Results: Intra-run CV (%) (n = 5) and bias (%) from the target values were higher for low creatinine concentrations. Especially Jaffe and enzymatic dry chemistry methods showed a higher error. The calculated eGFR values corresponding with the reported creatinine concentration ranges resulted in a different CKD classification in 47% of cases.

Conclusions: Although most creatinine assays claim to be traceable to the gold standard (ID-GC/MS), large inter-assay differences still exist. The inaccuracy in the lower concentration range is of particular concern and may lead to clinical misinterpretation when the creatinine-based eGFR of the patient is used for CKD staging. Further research to improve harmonization between methods is required.

Show MeSH
Related in: MedlinePlus