Isotonicity: The diluting fluid is made isotonic to maintain the integrity and shape of red blood cells (RBCs). Isotonicity means that the osmotic pressure of the diluting fluid is the same as that of the RBCs. This prevents RBCs from swelling or shrinking due to osmotic changes, which could alter their size and characteristics.
Fixation: The diluting fluid usually contains a fixative agent, which preserves the morphology of the RBCs. This is important for accurate microscopic examination of red cell shapes, inclusions, and other morphological features. The fixative agent stabilizes the RBCs, preventing any changes during the staining and analysis process.
Lysis of White Blood Cells (WBCs): Some diluting fluids contain a lysing agent that specifically lyses WBCs and platelets, leaving only the RBCs intact. This step is crucial in differential blood cell counts, where it is necessary to accurately count RBCs without interference from WBCs and platelets.
Staining Enhancement: Certain diluting fluids may contain specific chemicals that enhance the staining properties of RBCs. These additives facilitate better visualization of RBCs under the microscope by intensifying the staining intensity and making the cells more distinct. Improved staining allows for more accurate analysis and identification of abnormalities in red cell morphology.
Accurate Cell Counting: Isotonicity and fixation ensure that RBCs maintain their normal size and characteristics, which is essential for accurate cell counting. Proper cell counting is crucial for determining various hematological parameters, such as red cell count, hematocrit, and mean corpuscular volume (MCV).
By fulfilling these functions, the diluting fluid plays a vital role in ensuring the accuracy and reliability of hematological tests. It preserves the integrity of red cells, facilitates differential cell counts, enhances staining, and enables accurate cell counting. Proper formulation and standardization of the diluting fluid are essential for consistent and reliable hematology laboratory results.
