Trans Type Genotype Alpha Thalassemia Trait: A Case Study

Angela B Foley; Louann W Lawrence

doi:10.29074/ascls.16.2.79

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Angela B Foley, MS CLS(NCA)⇑
1. is Associate Professor, Louisiana State University Health Sciences Center, New Orleans LA
Louann W Lawrence, DrPH CLSpH(NCA)
1. is Professor and Department Head, Louisiana State University Health Sciences Center, New Orleans LA

Address for correspondence: Angela B Foley, Department of Clinical Laboratory Sciences, School of Allied Health Professions, Louisiana State University Health Sciences Center, 1900 Gravier Street, New Orleans LA 70112, (504) 568-4276, (504) 568-6761 (fax), afoley{at}lsuhsc.edu

Extract

A 22-year-old Caucasian female clinical laboratory science student agreed to donate several anticoagulated tubes of her blood to be used for analysis in the hematology student laboratory. She was in apparent good health and had no known history of a hematological disorder. Since manual white blood cell and platelet counts were being performed that day, her blood was run on an automated instrument so that the students' values could be checked for accuracy against the instrument values. Laboratory results (Table 1) and peripheral blood smear (Figure 1) are shown.

This complete blood count (CBC) was done on an instrument which employs impedance and pulse editing technology in measuring the mean corpuscular volume (MCV). This technology has been reported to result in a ‘clamped mean corpuscular hemoglobin concentration (MCHC)’ which may not accurately reflect hypochromia. Hypochromic cells are more deformable and therefore present a smaller cross sectional profile as the cells pass through the aperture to be counted and sized. This results in an MCV that is reported as slightly lower than it actually is. Since the hematocrit is calculated by multiplying the MCV by the red blood cell (RBC) count, the hematocrit value will also be falsely decreased and therefore the MCHC will be somewhat overestimated. The net result is a slightly decreased sensitivity of the MCHC to the presence of hypochromia.¹ However, a repeat CBC performed on a second instrument which employs pulse editing and hydrodynamic focusing reported a comparable MCHC of 32.4 g/dL. Hydrodynamic focusing has been reported…

ABBREVIATIONS: CBC = complete blood count; IDA = iron deficiency anemia; MCHC = mean corpuscular hemoglobin concentration; MCV = mean corpuscular volume; RBC = red blood cell; TIBC = total iron binding capacity.