Basic Classification Principles
Anemia is not just an isolated deviation in laboratory tests, but a complex typical form of pathology. In clinical practice and pathophysiology, anemia states are differentiated according to several main criteria. The fundamental vectors of evaluation include:
- Etiological factors (root causes of the pathology).
- Pathogenetic mechanisms (features of the origin and development of the disease).
- Clinical syndromes (a set of symptoms accompanying anemia).
For accurate laboratory diagnosis, morphological criteria are used: the degree of cell saturation with pigment, their physical size, as well as the rate of development of the pathology and the bone marrow response to the loss of erythrocytes.
Classification by Hemoglobin Saturation of Erythrocytes
This criterion reflects how densely the cell is filled with the respiratory pigment. The evaluation is carried out using the color index (CI), traditionally used in regional medicine, or the modern international index MCH (mean corpuscular hemoglobin).
There are three types of anemia based onchromia:
- Normochromic: physiological saturation. The CI is in the range of 0.85–1.05, and the MCH is 27–33 pg.
- Hypochromic: cells with a pronounced pigment deficiency. The CI drops below 0.85, and the MCH drops below 27 pg.
- Hyperchromic: cells oversaturated with hemoglobin. The CI exceeds 1.05, and the MCH becomes greater than 33 pg.
Classification by Erythrocyte Diameter and Volume
The size of red blood cells is a crucial diagnostic marker. It is assessed visually by a laboratory physician based on the cell diameter in a stained blood smear or automatically using a hematological analyzer via the MCV (mean corpuscular volume) index.
- Microcytic: abnormally small cells. The diameter is less than 7 µm, and the MCV drops below 80 fL.
- Normocytic: standard dimensions. The diameter varies from 7 to 8 µm, and the MCV remains within 80–100 fL.
- Macrocytic: giant cells. The diameter exceeds 8 µm, and the MCV increases to more than 100 fL.
Note: If erythrocytes of completely different sizes are simultaneously detected in a patient's blood smear, this pathological phenomenon is called anisocytosis (from Greek an — absence of something, iso — equal, cytos — cell).
Classification by Acuteness of Course and Degree of Compensation
The rate of development of the pathological process directly affects the severity of the clinical presentation and the adaptive capabilities of the body. According to the acuteness of the course, the following are distinguished:
- Acute anemia: a catastrophic condition that develops rapidly, within a few days.
- Chronic anemia: an indolent process that forms gradually—over the course of several weeks, months, or even years.
Classification by Degree of Compensation This parameter is entirely based on the functional ability of the bone marrow to generate new cells and adequately replace destroyed erythrocytes.
- Compensated: bone marrow reserves are sufficient, so hematological parameters remain within the physiological norm.
- Uncompensated: resources are depleted, the bone marrow cannot cope with the increased load, and hematological parameters inevitably go beyond the normal range.