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

Abstract

<jats:sec><jats:title>Aims</jats:title><jats:p>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.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>This study was performed on 96 remnants of peripheral blood samples (48 with MCHC in normal range and 48 with MCHC<jats:underline>&gt;</jats:underline>370 g/L) which have been analysed in different preanalytical conditions on the Sysmex analysers.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>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.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>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.</jats:p></jats:sec>

Correspondence: Response to “Eliminating or Minimizing the Effects of Cold Agglutinins on the Accuracy of Complete Blood Count Results”

“…Additional studies with larger sample sizes using duplicate or triplicate measurements are necessary to confirm and validate our single-case-based findings, like other recent studies [34]. We expect studies in a similar setting as ours, but with large sample sizes, to be performed in the near future [5]. Furthermore, we are aware that other factors, such as the titer of cold agglutinin and the presence of underlying disease, might cause analytical interference and remain to be further assessed [6].…”

<p>Cold agglutinin disease: current challenges and future prospects</p>

“…Prewarming at 37°C for up to 2 hrs will usually overcome this problem; if not, a short preheating at 41°C for 1 min may be tried. 37…”

Eliminating or Minimizing the Effects of Cold Agglutinins on the Accuracy of Complete Blood Count Results

“…Similar observations have not been described for Unicel DxH 800 and ADIVA 2120i, in which the environmental conditions in the RET channel do not lead to the spontaneous resolution of cold agglutination. Pre-heating at 41℃ for one minute has resulted in RBC counts similar to that of the RET channel and that of pre-heating at 37℃ for two hours [9].…”

“…In addition, the thermal amplitude of CA and titer in the blood determine the degree of hemolysis and amplitude of analytical “errors” [10]. Therefore, each CA-containing sample can react differently to the pre-analytical treatments, as previously described for 24 out of 48 samples that were not completely corrected even after pre-heating at 37℃ for two hours [9]. (ii) The complete reversibility of cold agglutination should be verified in every sample.…”

“…Based on these considerations, only microscopic observation of a slide performed using a sample prewarmed before counting (with the foresight to use a prewarmed glass slide) is useful for excluding (or confirming) the presence of residual RBC agglutination [9].…”