Spurious counts and spurious results on haematology analysers: a review. Part II: white blood cells, red blood cells, haemoglobin, red cell indices and reticulocytes

Abstract

S U M M A R YHaematology analysers provide quick and accurate results in most situations. However, spurious results, related either to platelets (part I of this report) or to other parameters from the cell blood count (CBC) may be observed in several instances. Spuriously low white blood cell (WBC) counts may be observed because of agglutination in the presence of ethylenediamine tetra-acetic acid (EDTA). Cryoglobulins, lipids, insufficiently lysed red blood cells (RBC), erythroblasts and platelet aggregates are common situations increasing WBC counts. In most of these instances flagging and/or an abnormal WBC differential scattergram will alert the operator. Several situations lead to abnormal haemoglobin measurement or to abnormal RBC count, including lipids, agglutinins, cryoglobulins and elevated WBC counts. Mean (red) cell volume (MCV) may be also subject to spurious determination, because of agglutinins, excess of glucose or salts and technological considerations. In turn, abnormality related to one measured parameter will lead to abnormal calculated RBC indices: mean cell haemoglobin content (MCHC) is certainly the most important RBC indices to consider, as it is as important as flags generated by the haematology analysers (HA) in alerting the user to a spurious result. In many circumstances, several of the measured parameters from CBC may be altered, and the discovery of a spurious change on one parameter frequently means that the validity of other parameters should be considered. Sensitive flags now allow the identification of several spurious counts, but only the most sophisticated HA have optimal flagging and more simple HA, especially those without a WBC differential scattergram, do not possess the same sensitivity for detecting anomalous results. Reticulocytes are integrated now into the CBC in many HA, and several situations may lead to abnormal counts.

Interpretation of automated blood cell counts

“…Analiz öncesi dönem olup hastaya, antikoagulanlı tüpe ve örneğin çalışma zamanına bağlı değişken-likler görülür (Tablo 1) [4,5].…”

“…-Hastaya bağlı faktörler: Hastanın hematolojik değerlerinde bozukluk olması (hiperlökositoz, eritrosit agglutinasyonu, eritrosit fragmantasyonu, hemoliz, soğuk agglutininler ve trombosit küme-leri), biyokimyasal değerlerinde bozukluk olması (Hiperglisemi veya dekstroz giden koldan kan alın-ması, hiperlipidemi, hiperbilirubinemi, disproteinemi) ve kan alınma şekli (küçük bebeklerden yetersiz veya pıhtılı kan alınması) etkili faktörlerdir [4][5][6].…”

“…Preanalitik hataların önlenmesi için kan alınma yeri, şekli ve hastanın tedavi durumu iyi bilinmeli, uygun kan örneği için hasta ismine ait etiketler kullanılmalıdır [4,5].…”

“…Sonuçlar önce laboratuarda değerlendirilmeli ve hataya neden olabilecek durumlar varsa gerekli düzeltmeler raporlanma öncesi yapılmalıdır [4,5].…”

Pseudothrombocytopenia

“…Th is antibody induces platelet agglutination in vitro, resulting in a decrease of platelet counts [1,2].…”