Erythrocyte sedimentation rate (ESR)
If the coagulant containing blood is left to stay in a tube in vertical position, erythrocytes will gradually deposit at the bottom. The rate of erythrocyte sedimentation is sensitive to the index of body's response to a lesion or disease, e.g., leukocytosis or fever. Normal ESR does not exclude the presence of disease, while an increase in ESR points to the need of additional testing. ESR is important for pointing to the possible existence of an organic disease, and is very useful in monitoring the course of disease.

 Erythrocytes (Erc)
Erythrocytes are most numerous blood cells (ranging from 3.86 x 10¹²/L to 5.08 x 10¹²/L in women, and from 4.34 x 10¹²/L to 5.72 x 10¹²/L in men).

 Leukocytes (Lkc)
Only mature cells, leukocytes, are found in the blood of healthy individuals. In some diseases, besides mature cells, juvenile or immature cells may also be transferred to the peripheral blood. Leukocyte count in the blood ranges from 3.4 x 10⁹/L to 9.7 x 10⁹/L. The values below 3 x 10⁹/L indicate leukopenia, and those above 10 x 10⁹/L leukocytosis.

 Hemoglobin (Hb)
The main role of hemoglobin is oxygen transport from the lungs to the tissues, and of CO₂from the tissues to the lungs, by labile oxygen and carbon dioxide binding to divalent heme iron.

 Hematocrit (Htc)
Hematocrit is the volume of erythrocytes in a whole blood unit. An anticoagulant inducing no changes in erythrocyte volume (e.g., K₃EDTA) is used for hematocrit determination.

 Platelets (Plt)
Platelet is a formation normally found in circulating blood. In blood smears, platelets are stained according to Pappenheim. Smears should be made from the blood withdrawn into anticoagulant (EDTA) containing tubes.

 Differential blood count (DBC)
Testing an individual's blood implies, among other procedures, preparation of peripheral blood smear to obtain data on the appearance, size and other cell characteristics, and to determine leukocyte formula. The smears of blood or other biological material thus obtained are stained by use of the classical method of May-Grünwald and Giemsa solutions (Pappenheim method). Blood smear examination provides general data on the size and appearance of cells as well as data on particular cell segments.

 Erythrocyte constants (MCV, MCH, MCHC, RDW)
Erythrocyte constants (MCV, MCH, MCHC, RDW) or corpuscular values are the values obtained by computation, which are used to determine erythrocyte characteristics.