Neutrophil Reactivity Intensity and misclassification of immature granulocytes.

INTRODUCTION: Immature granulocyte percentage (IG%) is an important biomarker for infection control. We observed spurious cases where the IG% was dramatically underestimated on the automated Sysmex XN-series hehmatology analyzer compared with manual differential. These cases were associated with high values of "Neutrophil Reactivity Intensity" (NEUT-RI), which should reflect the metabolic activity of the neutrophils. METHODS: We conducted a three-stage study to evaluate whether NEUT-RI could be utilized to screen for misclassified IG% results defined as the manual differential estimating a 10 percentage points higher IG% compared with the automated Sysmex differential. First, 124 patient samples were selected for 800-cell manual smear analysis based on their NEUT-RI values and compared with the automatic Sysmex IG% results. Next, 11 098 routine 110-cell manual smear analyses were compared with the corresponding Sysmex IG% results. Finally, during a 19-day period 160 additional patient samples underwent smear based on NEUT-RI values ≥56 fluorescence intensity (FI) to screen for misclassified results beyond our current smear practice. RESULTS: NEUT-RI ≥56 predicted IG% misclassification with 91% sensitivity and 88% specificity, but primarily when the internal Sysmex flag "Abnormal WBC Scattergram" was present. 90.1% of misclassified results were identified by this flag. Beyond our existing smear rules including this flag, NEUT-RI ≥56 FI had a positive predictive value below 1%. CONCLUSION: Both NEUT-RI and the internal Sysmex flag "Abnormal WBC Scattergram" work well to identify cases of IG% misclassification. However, in our setting NEUT-RI ≥56 FI had no meaningful additional predictive capacity to identify misclassifications beyond our current smear rules.

Interchangeability of multiple Sysmex XN10 and XN20 modules for six types of leukocytes.

INTRODUCTION: Differential counts of leukocytes are frequent, and often several automated blood cell counters are needed in contemporary laboratories. However, these modules are often individually quality assured. Our aim was therefore to validate the interchangeability of five hematology modules in a large modern laboratory and to compare them with our gold standard (GS) manual white blood cell differential count. METHODS: At Copenhagen University Hospital, we compared five Sysmex XN-modules for neutrophils, lymphocytes, monocytes, eosinophils, basophils, and immature granulocytes (IG). We analyzed control samples in three levels to evaluate intra- and intermodular precision. Bias between modules was evaluated by analyzing 93 random patient samples within reference intervals. XN-modules' mean counts were compared with GS. RESULTS: We found acceptable intramodular CV% (0.92%-8.76%), only neutrophils and eosinophils exceeded state-of-the-art imprecision or desirable specifications for medium control levels. Intermodular CV% showed significance difference for only monocytes (ANOVA, P < .0001). For patient samples, there were significant differences between XN-modules regarding four WBC types (ANOVA); however, proportional bias ranged from 1.7% to 3.8%, being within desirable specifications except basophils and IG (bias = 13.3% and 24.9%, respectively). Comparisons with GS, XN-modules exceeded desirable bias for basophils (lower than GS); monocytes and IG (higher than GS). CONCLUSION: This multimodule comparison shows acceptable intermodular imprecision and bias for clinical purposes, which is important for patient safety. Similar multimodule study should be performed with samples out of reference range in large-scale laboratories to confirm the interchangeability.

Hypo- and hypernatremia results in inaccurate erythrocyte mean corpuscular volume measurement in vitro, when using Sysmex XE 2100.

INTRODUCTION: Automated hematology analyzers dilute patient erythrocytes with an isoosmotic diluent before quantitating the erythrocyte mean cell volume (MCV). However, if patient plasma osmolality differs from the diluent, water will cross the erythrocytes membrane and establish a new equilibrium across the membrane. Since the new equilibrium is reached before the measurement of the MCV, the measured MCV may not reflect the true MCV in vivo. AIM: Calculation of the theoretical change in MCV at changed P-Sodium/P-Osmolality and to investigate if the automated blood cell counter Sysmex XE 2100 measures MCV correctly in hypo- and hyperosmolality and hypo-and hypernatremia. In addition, to examine whether the theoretically calculated change in MCV corresponds with the experimentally determined MCV change. METHOD: Theoretical calculation of the MCV inaccuracy at hypo- and hypernatremia, as well as at hypo- and hyperosmolality. Experimental studies with comparison of MCV measured at Sysmex XE 2100 to MCV found by using the manual measured packed cell volume method. RESULTS AND CONCLUSION: Measurement of MCV in hypo- and hypernatremia patients using the automated blood cell counter Sysmex XE 2100 resulted in inaccurate MCV. The experimental results also revealed a strong correlation between P-Osmolality/P-Sodium and MCV inaccuracy (R(2) = 0.70/0.85) similar to the theoretically calculated MCV inaccuracy. We suggest using mean cellular Hb (MCH) instead of MCV, mean corpuscular Hb concentration (MCHC) and B-Erythrocyte volume fraction (EVF). Alternatively, we suggest standardizing the measured MCV to a normal P-Sodium e.g. 140 mmol/L to estimate the in vivo MCV.