Hematology tests evaluate a variety of clinical conditions which include infection, anemia, inflammation, blood-clotting disorders, leukemia, etc. Some of the more common hematology tests include: complete blood count, white blood cell count, red blood cell count, platelet count, hematocrit, mononucleosis screen, hemoglobin levels, vitamin B12 levels, cholesterol levels, glucose levels, enzyme levels, and renal profiles. In general, hematology testing gives an accurate assessment of overall body health. The basic understanding of hematology testing requires knowing what happens to blood when centrifuged.
Blood can be separated into 3 layers by centrifugation if the blood is collected in the presence of an anti-coagulant (see Figure 1). The centrifugation process forms 3 layers in the test tube which include the: 1) plasma layer, 2) buffy coat layer, and 3) red blood cell (RBC) layer. The plasma layer is the top layer in the test tube and consists of the following: 90% water, 7% protein (e.g., albumin, fibrinogen, immunoglobulins, α-globulins, and β-globulins), and 2% other solutes (e.g., electrolytes, urea, creatine, creatinine, glucose, lipids, amino acids, oxygen, carbon dioxide, nitrogen, hormones, enzymes). The buffy coat layer is the middle layer in the test tube and consists of leukocytes (e.g., neutrophils, eosinophils, basophils, monocytes, and lymphocytes) and platelets. The red blood cell layer is the bottom layer in the test tube and consists of RBCs.
Figure 1: Hematology testing layering and component analysis
Blood can also be separated into 2 layers by centrifugation if the blood is collected in the absence of an anticoagulant (see Figure 1). The centrifugation process forms 2 layers in the test tube which include the: 1) serum layer and 2) blood clot layer. The serum layer is the top layer in the test tube. Serum is the same as plasma but without the blood clotting factors. The blood clot layer is the bottom layer in the test tube. The blood clot consists mostly of RBCs and leukocytes entrapped in a network of fibrin.
A full range of refrigerated centrifuges are available for hematology testing. Bench-top and floor-model centrifuges offer large-sample capacity with small footprints. Many centrifuges offer the ability to easily change rotors to allow multi-application use. In addition, there are a variety of centrifuges available for the specific preparation of platelet rich plasma (PRP), platelet rich fibrin (PRF), and platelet poor plasma (PPP).