Friday, March 24, 2023

How Are Hematology Analyzers and Reagents Indispensable in Clinical Diagnostics

According to the American Clinical Laboratory Association, more than 7 billion clinical lab tests are carried out annually in the U.S., giving vital information for a relatively low cost.

Healthcare professionals’ decisions about diagnosis and treatment are greatly influenced by the results of clinical laboratory testing. The information offered by clinical lab tests is assisting in the most accurate and efficient patient diagnosis, treatment, and monitoring at a time when evidence-based laboratory medicine (EBLM) is being employed by healthcare practitioners more frequently.

What are Hematology Analyzers and Reagents?

A hematology analyzer is one of the most widely used instruments for clinical testing in hospitals. It can be divided into human use and veterinary use according to the different objects of use.

The hardware of the two instruments is the same, but the difference lies in the software, in other words, the algorithm and reference range is different. It is worth noting that a veterinary hematology analyzer isn’t suitable for all kinds of animals.

Hematology analyzers count cellular components, perform some mathematics, and provide results for interpretation. For example, an elevated WBC count can indicate the presence of a bacterial infection, while a decrease in RBCs can indicate anemia. The numbers, mix, and ratios of these cells provide critical information to the clinician about the patient’s overall health and insight into specific conditions. With a basic understanding of the cells that constitute “whole” blood, we can move on to how the cells are counted.

The rising volume of blood donation in combination with the high prevalence of blood disorders is the major factor accelerating the growth of the hematology analyzers and reagents utility.

Types of Hematology Analyzers and Reagents

Before cells can be counted, a blood sample must be obtained from the patient and prepared for analysis. First, a phlebotomist draws a blood sample using a test tube coated with an anticoagulant to keep the blood from clotting. In the laboratory, the blood tube is continuously agitated (not shaken) to prevent the components from settling during any delays (performing tests on other samples, STAT lab tests, etc.) encountered in the process.

There are three methods of counting blood cells: manual, semi-automated, and fully automated, in two different designs. All hematology analyzers fall into either the semi- or fully-automated methods.

  1. The first, and the most traditional method is a manual count by direct observation. Manual counts are still performed when the exact number of certain cells is required. This is typically performed for abnormally shaped cells that are difficult to count automatically, such as those that occur with certain diseases.
  2. The second is a semi-automated method using quantitative buffy coat (the layer containing platelets and granulocytes) analysis (QBCA). This method obtains hematocrit (Hct), WBC, and Plt counts from both venous and capillary blood using a less labor-intensive process than a fully manual count.The blood is drawn into a special, stain-coated tube about the size of a microhematocrit tube. The tube is then sealed, incubated, and centrifuged using a special plastic float. The float settles between the RBCs and the plasma, separating their layers and (because the diameter of the float is slightly smaller than the inside diameter of the tube) expands the length of the buffy coat. The presence of the stain causes the buffy coat layers to fluoresce different colors.The laboratory technician manually examines the tube using a magnifier and a special light. The length of each layer of the tube, including the separated buffy coat, is measured as precisely as possible using a micrometer device. Particular cell counts (RBC, WBC, Hct, Plt, etc.) are determined using a conversion factor applied to the layer lengths. Other calculations, based upon measured values, can be manually performed by the laboratory technician as needed.
  3. Fully automated hematology analyzers employ two principal methods of counting blood cells: volumetric impedance and light-scatter technique. Both employ variations in the handling of samples before the count, such as automatic dilution and separation of samples into aliquots. One design dilutes the entire sample and then divides it into aliquots, while the other divides the sample and then dilutes each as required.In either case, the methodology requires the addition of a lysing agent to remove the RBCs, so that the WBC count can be performed with minimal interference. A second aliquot is further diluted before making RBC and Plt count. Some designs have the Hgb determination made on a third aliquot while others use one of the other aliquots.

Regulations Pertaining to Hematology Analyzers and Reagents in the USA

Under the Clinical Laboratory Improvement Amendments (CLIA), most hematology analyzers described in this article fall under the moderately complex regulatory category. Users of equipment in this category are required to have minimal scientific and technical knowledge and training to perform their duties accurately.

The test steps are either automatically executed (which is the case with most analyzers) or easily controlled, and minimal interpretation and technician assessment is required. These requirements and constraints pertain to the operation of the laboratory, testing facilities, and personnel performing the tests. Neither CLIA nor CAP nor the U.S. Food and Drug Administration (FDA) attempts to regulate or establish credentials for individuals maintaining these analyzers.

While CAP has maintenance criteria that must be followed to attain certification, neither they nor FDA specifies who will maintain laboratory equipment. Only the Joint Commission, which is not a regulatory agency, addresses maintainer qualifications and credentials.

Subscribe Now

    Hot Topics