Leukogram | Microscopy of Blood Formed Elements

Microscopy of blood formed elements (leukogram) is a manual evaluation of the percentage distribution of leukocyte classes, allowing for a more accurate determination of the morphological changes in blood cells. The examination is most commonly performed alongside a complete blood count (CBC) when a more detailed evaluation of inflammatory, infectious, or hematological processes is needed. The leukogram is assessed by a medical biologist, who counts 100 different leukocytes visible in the blood smear and determines their percentage distribution.

The main advantage of this examination is the ability to visually assess cell morphology and detect changes that automatic hematology analyzers may not identify. Such changes can include the appearance of blasts (characteristic of leukemia), atypical mononuclear cells (e.g., during viral infections), toxic granulation, Auer rods (signs of acute leukemia), and the presence of normoblasts or other atypical blood cells. Additionally, erythrocyte morphology (e.g., anisocytosis, poikilocytosis), changes in hemoglobinization, or pathological platelet forms can be evaluated.

Principle of the examination: A blood smear prepared on a slide from the patient's blood is stained with special dyes (e.g., Romanowsky or Wright-Giemsa) and later evaluated under a microscope to determine the percentage distribution and morphological changes of leukocytes.

Recommendations:

• Recommended when automatic CBC shows changes, unclear leukocytosis or leukopenia, suspecting hematological diseases or acute inflammatory processes.
• The examination is particularly valuable in differentiating the nature of infection (viral vs. bacterial), suspecting oncohematological diseases, autoimmune disorders.
• Leukogram results can be influenced by infections, stress, physical exertion, medications (e.g., glucocorticoids), as well as the quality of sample collection or preparation.
• It is recommended not to eat 8-12 hours before the examination, avoid intense physical exertion and stress to prevent physiological leukocytosis.