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Official Journal of the Society to Improve Diagnosis in Medicine (SIDM)

Editor-in-Chief: Graber, Mark L. / Plebani, Mario

Ed. by Argy, Nicolas / Epner, Paul L. / Lippi, Giuseppe / Singhal, Geeta / McDonald, Kathryn / Singh, Hardeep / Newman-Toker, David

Editorial Board: Basso , Daniela / Crock, Carmel / Croskerry, Pat / Dhaliwal, Gurpreet / Ely, John / Giannitsis, Evangelos / Katus, Hugo A. / Laposata, Michael / Lyratzopoulos, Yoryos / Maude, Jason / Sittig, Dean F. / Sonntag, Oswald / Zwaan, Laura

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Can citrate plasma be used in exceptional circumstances for some clinical chemistry and immunochemistry tests?

Davide Demonte / Mairi Pucci / Gian Luca Salvagno / Giuseppe Lippi
Published Online: 2019-05-04 | DOI: https://doi.org/10.1515/dx-2019-0027



The use of alternative sample matrices may be an advantageous perspective when the laboratory falls short of serum or lithium-heparin plasma for performing clinical chemistry and/or immunochemistry testing. This study was aimed at exploring whether some tests may be performed in citrate plasma as an alternative to lithium-heparin plasma.


Paired lithium-heparin and citrate plasma samples collected from 55 inpatients were analyzed on Roche Cobas 8000 for 28 different clinical chemistry and immunochemistry parameters. Data obtained in citrate plasma were adjusted for either the dilution factor or using an equation corresponding to the linear regression calculated by comparing unadjusted lithium-heparin and citrate plasma values.


Except for magnesium (+17%) and sodium (+11%), unadjusted values of all remaining analytes were significantly lower in citrate than in lithium-heparin plasma, with bias ranging between −6.4% and −25.9%. The correlation between lithium-heparin and citrate plasma values was generally excellent (i.e. >0.90). The adjustment of citrate plasma values for the dilution factor (i.e. 1.1) was only effective in harmonizing the results of albumin and lipase, whilst the concentration of all other analytes remained significantly different between the two sample matrices. The adjustment of plasma citrate values using corrective formulas was instead effective in harmonizing all parameters, with no results remaining statistically different between the two sample matrices.


Citrate plasma may be used in exceptional circumstances for clinical chemistry and immunochemistry testing as a replacement for lithium-heparin plasma, provided that citrate plasma values are adjusted by using validated corrective equations.

Keywords: citrate; clinical chemistry; lithium-heparin; preanalytical variability


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About the article

Corresponding author: Prof. Giuseppe Lippi, Section of Clinical Biochemistry, University Hospital of Verona, Piazzale LA Scuro, 37134 Verona, Italy

aDavide Demonte and Mairi Pucci contributed equally to this work.

Received: 2019-03-29

Accepted: 2019-04-18

Published Online: 2019-05-04

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.

Citation Information: Diagnosis, 20190027, ISSN (Online) 2194-802X, ISSN (Print) 2194-8011, DOI: https://doi.org/10.1515/dx-2019-0027.

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