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Abstract
Incidentally, hemoglobin (Hb) variants can be detected using HbA1c tests in clinical laboratories. We found 38 patients with Hb variants after reviewing a total of 29,398 HbA1c test results from January 2017 to December 2017. While reviewing the complete blood count results of the patients (N=36) using the Sysmex XN-9000 analyzer (Sysmex, Japan), 35 patients were flagged as unremarkable with respect to differential white blood cell (WBC) counts. However, 1 patient with a normal WBC count did not obtain a differential WBC count while being flagged for an abnormal WBC scattergram in the white blood cell differential (WDF) channel. The WBC histogram showed an abnormally low fluorescent signal in the WDF channel; however, the differential WBC count was normal upon microscopic examination. After testing the patient's buffy coat suspended in normal saline and removing red blood cells (RBCs), the WBC scattergram and differential WBC count returned to normal. This finding suggests that the presence of a patient's RBCs may affect WBC scattergrams and Hb variants may interfere with the fluorescent dye in the differential WBC count. Therefore, when an abnormal WBC scattergram with an abnormally low fluorescent signal is encountered on the Sysmex XN-9000 analyzer, the presence of an Hb variant can be suspected.
References
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Fig. 1.
WBC scattergrams from the automated hematology analyzers. (A), (B), (C), (D), and (E) were performed on the Sysmex XN-9000 analyzer and (F) on the ADVIA 2120i analyzer. (A) Scattergram of the white blood cell differential (WDF) channel of the patient. (B) Scattergram of the patient's buffy coat suspension in phosphate buffered saline after removing RBCs. (C) Scattergram of the patient's WBCs and RBCs containing normal saline instead of plasma. (D) Scattergram of a sample containing a normal control's WBCs and the patient's RBCs. (E) Scattergram of the normal control. (F) WBC scattergram of the patient. Abbreviations: SFL, side fluorescent light; SSC, side scattered light.
Table 1.
Hematologic characteristics of the cases with Hb variants exhibiting abnormal WBC scattergrams detected using a Sysmex series analyzer and from literature reviews
| Reference | Case no. | Sex | Age (yr) | Hb (g/dL) | MCV (fL) | RDW (%) | RET (×109/L) | HbA2 (%) | Hb variant |
|---|---|---|---|---|---|---|---|---|---|
| This study | 1 | M | 41 | 13.0 | 104.1 | 14.1 | 679.8 | 3.9 | NT |
| 3 | 2 | F | 37 | ∗ | ∗ | ∗ | ∗ | 2.8 | Leiden |
| 4 | 3 | F | 52 | ∗ | ∗ | 15.2 | ∗ | 41.8 | G-Ferrara |
| 5 | 4 | M | 76 | ∗ | ∗ | ∗ | ∗ | ∗ | M Dothan |
| 6 | 5–1 | F | 72 | 12.1 | 80.9 | 17.9 | 144.9 | 3.0 | Indianapolis |
| 6 | 5–2 | M | 44 | 13.3 | 88.1 | 15.7 | 258.5 | 3.1 | Indianapolis |
| 6 | 5–3 | F | 40 | 13.6 | 86.9 | 13.1 | 128.0 | 3.3 | Indianapolis |
| 6 | 5–4 | F | 36 | 14.2 | 92.1 | 13.3 | 187.3 | 3.1 | Indianapolis |
| 6 | 6–1 | M | 45 | 14.9 | 97.1 | 13.5 | 161.4 | 3.8 | Köln |
| 6 | 6–2 | M | 8 | 11.9 | 95.4 | 15.3 | 183.0 | 3.4 | Köln |
| 6 | 7 | M | 14 | 13.0 | 86.8 | 14.3 | 235.0 | 3.6 | Köln |
| 6 | 8 | F | 59 | 14.7 | 97.9 | 13.6 | 87.7 | 2.8 | Himeji |
| 6 | 9 | M | 81 | 16.3 | 93.9 | 14.9 | 137.9 | 3.5 | HBB: C.173A > T |
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