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Short preheating at 41°C leads to a red blood cells count comparable to that in RET channel of Sysmex analysers in samples showing cold agglutination
  1. Antonio La Gioia1,
  2. Maurizio Fumi2,
  3. Fabiana Fiorini3,
  4. Paola Pezzati4,
  5. Fiamma Balboni5,
  6. Maria Bombara6,
  7. Alessandra Marini7,
  8. Ylenia Pancione2,
  9. Leonardo Solarino8,
  10. Elisa Marchese8,
  11. Silvia Sale2,
  12. Vincenzo Rocco2,
  13. Marcello Fiorini6
  1. 1 Docemus Onlus “Theoretical and Practical Training School for Improving Specialty Medicine”, Torrevecchia Teatina, Italy
  2. 2 U.O. Patologia Clinica A.O.R.N. “G.Rummo”, Benevento, Italy
  3. 3 UOC Medicina di Laboratorio Azienda USL Toscana Nord Ovest, Pontedera, Italy
  4. 4 Centro Regionale Controllo di Qualità AOU Careggi, Firenze, Italy
  5. 5 Laboratorio Analisi IFCA (Istituto Fiorentino di Cura ed Assistenza), Firenze, Italy
  6. 6 UOC Medicina di Laboratorio Azienda USL Toscana Nord Ovest, Livorno, Italy
  7. 7 UOC Medicina di Laboratorio Azienda USL Toscana Nord Ovest, Versilia, Italy
  8. 8 UOC Laboratorio Analisi I - Policlinico Vittorio Emanuele, Azienda Universitaria Ospedaliera, Catania, Italy
  1. Correspondence to Dr Antonio La Gioia, Docemus Onlus “Theoretical and Practical Training School for Improving Specialty Medicine”, Torrevecchia Teatina, Italy; ant.lagioia{at}


Aims The presence of cold agglutinin in blood samples can cause a spontaneous agglutination of red blood cells (RBCs) when low temperature occurs. This phenomenon causes a spurious lowering of RBC count on the automated haematological analysers that are detected by incongruous values (≥370 g/L) of the mean cellular haemoglobi concentration (MCHC). A preheating at 37°C can remove the RBC agglutination generally resulting in a reliable count. It has been reported that the same result can be reached by using the optical reticulocyte (RET) channel of Sysmex analysers where the RBC count is not influenced by the presence of cold agglutinin. This study aims to evaluate these data in a larger population, with regard to environmental conditions on Sysmex analysers. We have also evaluated the influence of different thermal pretreatments on the RBC count.

Methods This study was performed on 96 remnants of peripheral blood samples (48 with MCHC in normal range and 48 with MCHC>370 g/L) which have been analysed in different preanalytical conditions on the Sysmex analysers.

Results A preheating of samples at 41°C for 1 min leads to a reversibility of the cold agglutination comparable to the one observed in the RET channel and yields better results compared with 37°C for 2 hours.

Conclusions None of described procedures assure the complete cold agglutination reversibility in every case. Consequently, since the haematological analysers not yet provide reliable parameters to confirm the complete resolution of agglutination, further verification of RBC count accuracy needs to be performed.

  • cold agglutination
  • mean cellular hemoglobin concentration
  • sysmex analyzers
  • reticulocytes count

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  • Handling editor Mary Frances McMullin.

  • Contributors ALG, FB and VR planned and designed the study. ALG, FF, FB, AM, MB, YP, LS and EM selected and evaluated the studied cases. ALG, VR, SS and MF performed and revised the manuscript. MF and PP performed statistical analysis. PP and MB revised English language. All authors read and approved the manuscript.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.