Blood test for PDW( platelet-by-volume distribution)

One of the most accessible and effective types of examination in medicine is a general blood test. It is the most common and is prescribed in almost all cases of treatment to a physician-therapist. Changes in the composition of the blood make it possible to suspect the development of many diseases at the initial stage, as well as to establish the causes of these or other symptoms. During the clinical analysis, the parameters of all blood elements are evaluated. To date, there are more than 20 important indicators, including PDW.This is one of the platelet blood indices. Explanation of the abbreviation - the width of the distribution of platelets by their volume. This indicator reflects the heterogeneity of the population of blood platelets in size and reflects the degree of anazocytosis - changes in cell size. That is, the platelets in the blood differ in size from each other, and the analysis on PDW shows what percentage of the total amount is made up of micro- and macroblots.


The platelet count by volume should normally be between 15 and 17%.Admissible minor deviations - 1-2%, which can be due to the individual characteristics of the organism.

How the

is Performed The PDW value is determined during a general blood test along with many other indicators. Blood is taken from the finger( nameless) on an empty stomach in the morning hours. For the study, whole blood with an anticoagulant is used.

The result may be unreliable if the patient took food before the analysis, at this time, is treated with medications or the day before the X-ray examination or physiotherapy. In addition, the indicator may be higher or lower than normal during pregnancy, before menstruation, after severe mental or physical exertion. In such cases, a re-study is prescribed. To avoid distortion of the results, you should prepare for the analysis correctly.

In our time, modern hematology analyzers are used for blood testing, on which up to 24 indicators are obtained. For effective diagnosis is not enough to determine only the volume of platelets. Normal hemostasis depends not only on the quantitative content of non-nuclear plates, but also on their functional indices. Therefore, it is so important to investigate their quality characteristics, which is possible only with new equipment. The hardware methods of studying blood elements have many advantages over manual ones:

  • examines a large number of cells - from 10,000;
  • provide an accurate result - without errors;
  • all stages of the study are standardized.

With the help of modern blood analyzers, histograms are obtained - a graphical representation of the results in the form of thrombocytometric curves. The importance of this study is due to the fact that the platelet sizes depend on their functional capabilities, the change in their volume before gluing the plates in the process of clot formation, as well as the propensity for adhesion and the content of bioactive substances in non-nuclear cells.

Automatic blood analyzer
Apparatus methods of blood testing allow obtaining accurate results in shorter terms

If the blood contains predominantly young platelets, the histogram is shifted to the right, the old plates are located on the graph to the left. Thus, the volume of platelets decreases as they grow older.

Interpretation of the

analysis The interpretation of the results is the responsibility of the attending physician. The deviation of the PDW from normal indicates a violation of the size of the population of non-nuclear cells. An increase in this indicator may be due to the presence of micro-erythrocytes, fragments of erythrocytes, aggregates of platelets. Changes in PDW can occur in myeloproliferative diseases. This group includes such pathologies:

  • myelofibrosis,
  • essential thrombocythemia,
  • chronic myelogenous leukemia,
  • true polycythemia.

The platelet distribution index PDW helps identify the following pathologies:

  • inflammatory diseases,
  • anemia,
  • parasitic infections( helminthic invasion),
  • malignant disease,
  • state of the vascular walls.

The platelet index value is not considered separately, but only in combination with other indicators.

Reasons for increasing

Also you can read: platelets
Why is blood platelet lowering in the blood test?

The PDW value can be increased for the following reasons:

  • anemia of different origin;
  • presence of inflammatory diseases;
  • significant loss of blood;
  • physical overvoltage;
  • removal of the spleen;
  • recovery period after surgery;
  • course of treatment with corticosteroids;
  • oncological diseases.

If the width of platelet distribution is higher than normal, a person may experience:

  • general weakness and malaise throughout the day;
  • disability reduction.


A general blood test provides an opportunity to evaluate both the quantitative content of its components and the quality of the shaped elements. The study of the platelet blood fraction is an important part of the analysis of the clotting system. For this, a whole set of specific tests is required. Additional indicators allow us to evaluate the morphological characteristics of denuclearized plates and their functional activity. One of the important parameters in the diagnosis is the platelet index PDW, or the relative width of the distribution by volume. If this indicator is higher or lower than the normal value, it is possible that the body develops an inflammatory process or other diseases.