The distribution width of erythrocytes is the standard deviation. What does a blood test for RDW mean. What is RDW in blood

The Red Blood Cell Distribution Index (RDW) is a very important factor during a complete blood count. This indicator shows the size and shape of red blood cells.

Red blood cells realize the function of transportation, thereby assisting in the penetration of oxygen into all tissues and organs, while taking away toxins and carbon dioxide accumulated in cells. AT normal condition red blood cells are approximately the same size, which allows them to quickly stick together, forming blood clots.

How is it calculated?

The RDW indicator is calculated as a percentage, the norm of which is the limit from 11.5 to 14.8. The distribution index of erythrocytes is determined using a mathematical equation, which is the ratio of modified red blood cells and their total mass.

At present, laboratories use computer technology that allows you to calculate the percentage of deviation from the established norm. The results of the calculation are presented in the form of a histogram depicting a curve that indicates the likely changes in the size of red blood cells.

Normal performance

The norms of the erythrocyte distribution index depend on gender, age and the presence of certain conditions that occur in the human body. For children up to a year normal rate is 11.5-18.7%. AT one year old and older values ​​rush to the generally accepted norm of 11.5-14.5%.

For the female half of humanity, the upper limit shifts to 15.5%, because their hormonal levels change too often: during pregnancy, lactation, taking oral contraceptives, menopause.

For analysis, blood is taken on an empty stomach in the morning (until 9 am). It is very important that before this procedure, the person does not take any medicines and was also in a balanced internal state.

Raise RDW

The level of RDW in some situations is elevated. The most common cause of this pathology is iron deficiency anemia. The indicator can change at different stages of the development of pathology, which clearly reflects the histogram of erythrocytes:

• The initial stage of the development of anemia is characterized by normal indices, but hemoglobin will be greatly reduced. This is the result of healthy functioning of the spinal cord.
• The next stage of development in the histogram will show increase in RDW. When there are problems with hemoglobin, indicators such as the average concentration and content of hemoglobin in the blood cell, the average volume of red cells decrease.

In the treatment of IDA, it is necessary to normalize the level of iron-containing protein concentration and its characteristics in human blood.

What do low scores mean?

Patients often ask what it means: "erythrocyte distribution index is lowered." Since the erythrocyte distribution index cannot be estimated without a volume indicator, it is necessary to familiarize yourself with all options for underestimated indicators with their relationship:

1. RDW is low, and MCV is below average - indicates the presence of problems with the spleen and liver.
2. RDW down and MCV up normal level- indicates the presence of oncological pathologies, mainly the development of metastases in the bone marrow.

That the distribution index erythrocyte RDW sd downgraded, with biological point vision, cannot, in principle, be observed. For this reason, most often the patient is offered to donate blood again, observing the following conditions:

• stop smoking and drinking alcohol within 24 hours before blood sampling;
• before the analysis, do not take any medications;
• refuse to eat smoked and salty foods the day before.

In the case when the distribution index of erythrocytes RDW sd is really lowered, which is necessarily confirmed by deviations from the norm of the MCV indicator, this indicates the occurrence of certain pathologies. These include:

• Hypochromic microcytic anemia - sometimes also called anemia. A condition in which irregularly shaped red blood cells die because they have no biological value in the body.
• Malignant tumors - usually in this case we are talking about mastopathy, cancer bone marrow and lungs.
• Hemolysis of red blood cells is the process during which red blood cells die before reaching their target. As a result, active hemoglobin is released.

The reasons

So, the distribution index of erythrocytes is lowered - what does this mean? There are several reasons that can lower the RDW:

• Acute blood loss due to trauma and pathological bleeding.
• Frequent operations.
• A metabolic disorder in which the food consumed is not completely digested.
• Hormonal failure, which is most common in women.
• Deficiency in the body of B vitamins and iron.
• Blood diseases characterized by rapid destructive processes.

What measures to take?

What to do when the erythrocyte distribution index is lowered?

A highly qualified doctor at the consultation will most likely ask the patient to take the test again, because the RDW indicator is almost never underestimated. Since this suggests that all cells are ideal in their parameters, and this, in principle, cannot be. If the indicator is confirmed upon re-analysis, then a complete study of the state of the body is carried out, paying attention to Special attention oncological examinations.

Preventive measures

You can prevent a low RDW by following these simple rules:

• The diet should be balanced, which includes a lot of fresh fruits, lean meat and vegetables.
• It is recommended to breathe fresh air as often as possible.
• An active lifestyle will help prevent the RDW index from dropping.
• It is very important not to miss scheduled medical examinations, during which serious deviations from the norm are most often detected that do not have external symptoms.

As a result, we learned that the distribution index of erythrocytes reflects their dimensions relative to each other and makes it possible to learn about their biological value. downgrade RDW it is very rare, but if the distribution index of erythrocytes is lowered, this means that various pathologies are possible.

The index is calculated based on the results of a general blood test, but it can only be fully valid in conjunction with the MCV indicator, since they are closely interconnected.

How to take a general blood test and what is needed for this?

There are no complex, strict regulations regarding this testing, but there are some rules:

• For this survey use capillary blood, which is taken from a finger. Less commonly, according to the doctor's instructions, blood from a vein may be used.
• The analysis is carried out in the morning. The patient is forbidden to eat food, water 4 hours before taking a blood sample.
• The main medical supplies that are used for taking blood are a scarifier, cotton wool, and alcohol.

The algorithm for taking capillary blood is as follows:

• The finger from which blood sampling is planned is treated with alcohol. For better blood sampling, it is useful to rub your finger first to ensure a better blood flow to it.
• A scarifier is used to pierce the skin on the finger.
• Blood is collected using a small pipette. The sample is placed in a sterile tube.

What the general blood test shows - deciphering the general blood test of a child and an adult, the norms in the tables and the reasons for the deviation from the norms.

Everyone has gone through this in their life. painless procedure like donating blood from a finger. But for the majority, the result remains only a set of numbers written down on paper. Explanations of this analysis will enable each patient to navigate the deviations that are detected in the blood, the reasons that caused them.

Complete blood count - the content of hemoglobin in the blood.

This blood component is a protein through which oxygen enters all internal organs / systems. The amount of this component is calculated in grams, which is in 1 liter of blood.

• Norms of hemoglobin content in the blood in children and adults.

This indicator will depend on the age of the patient, his gender:

• Reasons for increased and reduced level hemoglobin in children and adults.

Elevated hemoglobin levels are observed with:

1. Diagnosis of heart disease.
2. Diseases of the kidneys.
3. The patient has pathologies associated with hematopoiesis.

A low hemoglobin level may be the result of:

1. Vitamin/iron deficiency.
2. Significant blood loss.
3. Blood cancer.
4. anemia.
5. Rigid diet that led to exhaustion.

Erythrocytes in the general blood test.

Inside the components under consideration contains hemoglobin. The main purpose of erythrocytes is to carry oxygen to internal organs. Often in the table, instead of the unit of measurement of erythrocytes, you can see the abbreviation RBC.

• The norm of the content of erythrocytes in the blood in children and adults.

The given indicator must be multiplied by 1012. The result will be equal to the number of red blood cells that are present in 1 liter. blood:

• In newborns on the 1st day of life: not less than 4.3, not more than 7.6.
• In infants up to a month, this figure decreases: 3.8-5.6.
• 1-6 months: 3.5 to 4.8.
• Up to 1 year: not higher than 4.9, not lower than 3.6.
• 1 to 6 years: 3.5 to 4.5.
• In the age range of 7-12 years bottom line allowable rate increases to 4.7.
• In adolescence (up to the age of 15): 3.6-5.1.
• From the age of 16 (men): not higher than 5.1, not lower than 4.
• From 16 years old (women): from 3.7 to 4.7.

• Causes of increased and decreased levels of red blood cells in children and adults.

The factors that provoke an increase / decrease in the number of red blood cells in the blood are similar to those that cause an increase / decrease in hemoglobin.

The width of the distribution of erythrocytes in the general blood test.

This parameter directly depends on the size of erythrocytes: when detecting a large number erythrocytes of different sizes in the taken blood sample, one can speak of a high width of the distribution of erythrocytes.

• The norm of the width of the distribution of erythrocytes in the blood in children and adults.

This indicator is identical for children, adults, and can vary from 11.5 to 14.5%.

• Causes of increased and decreased levels of the width of the distribution of erythrocytes in children and adults.

Deviation from the norm of the indicator under consideration may occur against the background of malnutrition, anemia, dehydration.

The average volume of erythrocytes in the general blood test.

This blood parameter helps to obtain information about the size of red blood cells. It is measured in femtoliters / micrometers cubed. This volume is calculated using a simple formula, for which you need to know the percentage of hematocrit, the number of red blood cells.

• The width of the distribution of erythrocytes is the norm in children and adults.

Regardless of age, gender patient, normal the considered blood parameter (MCV) should not be higher than 95 fl, not lower than 80 fl.

• Causes of increased and decreased indicators of the width of the distribution of erythrocytes.

Lowering the rate often occurs due to a lack of iron.

Increase in indicator MCV indicates a deficiency of certain micronutrients.

The average content of hemoglobin in an erythrocyte - a complete blood count, norms and deviations.

The resulting indicator (MCH) displays the amount of hemoglobin that is contained inside the 1st erythrocyte. It is calculated according to a certain formula, for which you need to know the amount of hemoglobin + erythrocytes. The specified parameter is measured in picograms. The MCH norm is the same for men, women, children: 24-33 pg.

Lowering the rate often occurs due to iron deficiency anemia.

Increase in indicator MCH is the result of a folic acid/vitamin B12 deficiency.

The average concentration of hemoglobin in an erythrocyte - a complete blood count, norms and deviations.

The parameter in question (MCHC) is obtained by mathematical calculations using hemoglobin+hematocrit. The unit of measure is %. The norm of hemoglobin content in an erythrocyte varies within 30-38%.

There are several factors that can cause a decrease in the indicator in relation to the specified norm:

1. Diseases of the blood.
2. iron deficiency.

The probability of an increase in the indicator under consideration is scanty.

Erythrocyte sedimentation rate in the general blood test.

This indicator (ESR) is obtained by settling the taken blood sample. It is determined by the number, shape of red blood cells, measured in mm / h. The process under consideration is also influenced by the amount of proteins in the plasma.

• The rate of erythrocyte sedimentation in the blood in children and adults.

This parameter does not change much with age, but there are differences:

• 1st day of life: 2-4.
• In babies up to a month: from 4 to 8.
• In the period up to 6 months. ESR norm is 4-10.
• From 1 to 12 years: not higher than 12, not lower than 4.
• From 13 to 15 years, the lower limit of the norm increases to 15.
• From 16 years old (men): 1-10.
• From 16 years old (women): 2-15.

• Causes of increased and decreased erythrocyte sedimentation rate in children and adults.

The upward deviation from the norm is the result of such phenomena:

• body infection.
• Pregnancy.
• Anemia.

A decrease in ESR is the result of blood diseases.

Leukocytes in the general blood test.

These are living cells of the body that are produced in the lymph nodes, bone marrow, perform a controlling function. There are several varieties of blood components under consideration: neutrophils, monocytes, eosinophils, lymphocytes, basophils.

• The norm of leukocytes in the blood in children and adults.

The result will correspond to the percentage of leukocytes that are normally present in 1 liter of blood:

• On the 1st day of life: from 8.5 to 24.5.
• In babies up to 1 month: from 6.6 to 13.8.
• In the first six months, the norm should not exceed 12.5, it cannot be less than 5.5.
• In the age range from 1 month. up to 1 year: 6 to 12% per liter of blood.
• From 1 to 6 years: no more than 12, no less than 5.
• At the age of 7-12 years: from 4.4 to 10.
• In adolescence (after the age of 15): not higher than 9.5, not lower than 4.4.
• From 16 years old (men/women): from 4 to 9.

• Causes of increased and decreased levels of leukocytes in children and adults.

An increase in the rate can occur due to the influence of several factors:

• Inflammatory phenomena in the body. This includes postoperative period, ENT diseases, diseases of the lower respiratory tract, damage skin as a result of injury/burn. With cancer, general blood testing will also show an elevated level of leukocytes.
• Pregnancy.
• Menstruation.
• Vaccination.

The level of leukocytes can be reduced under the influence of such phenomena:

• Vitamin B12 deficiency.
• Diseases of the blood.
• A specific group of infectious diseases: malaria, viral hepatitis, typhoid fever.
• The influence of radiation.
• Systemic lupus erythematosus.
• Taking certain medications.
• Conditions in which immunodeficiency occurs.

Platelets in the general blood test.

These are small non-nuclear cells, inside which microelements are contained, which ensure blood clotting.

• The norm of platelets in the blood in children and adults.

The given indicator must be multiplied by 109 .. The result will correspond to the number of cells that are normally present in 1 liter of blood:

• 1st day after birth: 180-490.
• In children from 1 month. up to 1 year: not higher than 400, not lower than 180.
• From 1 to 6 years: 160-390.
• In the age range of 7-12 years: not higher than 380, not lower than 160.
• In adolescence (up to 15 years old inclusive): from 160 to 360.
• From 16 years old (men / women): from 180 to 320.

• Causes of high and low platelets in children and adults.

An increase in the norm can occur under the influence of several phenomena:

• Inflammatory reactions (including the postoperative period).
• Oncological diseases.
• Significant blood loss.
• Diseases of the blood.

A low level of platelets is observed against the background of the following pathologies:

• Defects in the work of the bone marrow.
• Cirrhosis of the liver.
• Blood transfusion.
• Disorders associated with the functioning of the immune system.
• Diseases of the blood.

Hematocrit in the general blood test.

By means of this parameter, the volume of erythrocytes is compared with the volume of blood. The unit of measure for hematocrit is percent.

• Hematocrit in the blood and its norm in children and adults.

With age, this parameter undergoes certain changes:

• On the 1st day after birth: 40-66%.
• In children up to a month: from 34 to 55%.
• In infants in the age range of 1-6 months: 32-43%.
• From 1 to 9 years: 34-41%.
• From 9 to 15 years: 34-45%.
• From 16 years old (women): no more than 45%, no less than 35%.
• From 16 years old (men): 39-49%.

• Low and high hematocrit in children and adults.

An increase in the considered blood parameter occurs when:

• Heart/lung failure.
• Dehydration.
• Some blood diseases.

A decrease in hematocrit may indicate the following phenomena:

• III-IV trimester of pregnancy.
• Anemia.
• Renal failure.

Granulocytes in the general blood test.

This blood parameter is represented by several groups of cells: basophils, neutrophils, eosinophils. These granule bodies are indispensable participants in the fight against infections and microbes.

• The norm of granulocytes in the blood in children and adults.

There are two options for presenting this blood parameter:

• Absolute score. It will be referred to as GRA# on the blood test result tables. In this context, the rate of granulocytes can vary from 1.2 to 6.8 * 109 cells per 1 liter.
• The percentage of granulocytes to leukocytes. Has the designation GRA%. The norm should not be more than 72%, less than 47%.

• Causes of an increase and decrease in granulocytes in the blood in children and adults.

With inflammatory phenomena in the body, an increase in granulocytes in the blood occurs.

A decrease in the number of considered elements in the blood can occur for several reasons:

1. Malfunctions in the bone marrow, which are associated with the production of blood cells.
2. The patient is diagnosed with systemic lupus erythematosus.
3. Taking certain medications.

Monocytes in the general blood test.

Important components of the immune system. Their duties include the recognition of microorganisms dangerous to the body, the fight against inflammatory foci. Their number is limited.

• The norm of monocytes in the blood in children and adults.

The given indicator (MON%) displays the percentage of monocytes in total leukocytes:

• Babies up to 1 year old: 2-12%.
• From 1 to 15 years: not more than 10%, not less than 2%.
• From 16 years old (women/men): from 2 to 9%.

• Causes of an increase and decrease in monocytes in the blood in children and adults.

The increase in the rate can be due to several factors:

The decrease in monocytes occurs against the background of the following phenomena:

• Childbirth.
• Postoperative rehabilitation.
• Taking anticancer drugs.
• Inflammatory-purulent phenomena.

Neutrophils in the general blood test.

These cells help the body cope with infections, eliminate its own extinct microparticles. According to their structure, they are divided into two groups: mature, immature.

• The norm of neutrophils in the blood in children and adults.

The indicator under consideration displays the percentage of stab, segmented neutrovils in the total number of leukocytes. Consider the rate of stab in the blood in children, adults:

• On the 1st day after birth: 1-17%.
• In children from 1 month up to 1 year: from 0.5 to 4%.
• Age group 1-12 years: 0.5-5%.
• From 13 to 15 years old: not more than 6%, not less than 0.5.
• From 16 years old (women/men): 1-6%.

The indicators of the norm of segmented nuclei in the blood are as follows:

• In newborns on the 1st-3rd day of life: not more than 75-80%, not less than 45%.
• Babies from 1 month up to 1 year: from 15 to 45%.
• Age group 1-6 years: 25-60%.
• From 7 to 12 years old: no more than 66%, no less than 34%.
• In adolescence (up to 15 years inclusive.): 40-65%.
• 16 years old (women/men): 47-72%.

• Reasons for the increase and decrease in neutrophils in children and adults.

An increase in the number of neutrophils can be triggered by such phenomena:

• body infection.
• Oncological diseases.
• Vaccination.
• inflammatory phenomena.

A decrease in neutrophils in the blood may occur due to:

1. Treatment aimed at eliminating cancer: chemotherapy, medication. Taking other drugs that inhibit the protective capabilities of the body.
2. Errors in the work of the bone marrow.
3. Irradiation.
4. "Baby" infectious diseases(rubella, measles, etc.).
5. An excess of hormones that are produced by the thyroid gland.

Eosinophils in the general blood test.

The given indicator displays the percentage of eosinophils in the total number of leukocytes:

• On the 1st day of a baby's life: 0.5-6%.
• In the age range of 1 month-12 years: not more than 7%, not less than 0.5%.
• Age group 13-15 years: not more than 6%, not less than 0.5%.
• From 16 years old (women/men): from 0 to 5%.

• Reasons for the increase and decrease in eosinophils in children and adults.

An increase in the number of these cells can occur against the background of:

A decrease in eosinophils can be triggered by:

• Childbirth.
• Infection of the body (including the postoperative period).
• Chemical poisoning.

Basophils in the general blood test.

When testing the blood, these cells may not be detected: the fewest elements of the immune system. Consist of microparticles that provoke the occurrence inflammatory phenomena in tissues.

• The norm of basophils in the blood in children and adults.

Displays the percentage of eosinophils in the total white blood cell count. For children of any age, male/female patients, the number of eosinophils should be 0-1%.

• Reasons for the increase and decrease in basophils in children and adults.

An increase in the considered component of the blood occurs when:

• Allergic conditions.
• Lack of hormones: errors in work thyroid gland taking hormonal drugs.
• Chicken pox.
• Pathologies of the lymphatic system.

A decrease in basophils can be caused by:

• Pregnancy/ovulation.
• An increase in the number of hormones.
• Stress.

All norms of a general blood test for children and adults in tables

Table 1: Norms of a clinical blood test for children different ages

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I continue to acquaint you with the decoding of the abbreviations that can be seen in the analysis form, which produces a hemolytic analyzer. In this post, we will talk about such an indicator as RDW in a blood testor the width of the distribution of erythrocytes, which is determined by most modern devices. This is one of the erythrocyte indices, among which should also be mentioned , .

The RDW index reflects the heterogeneity of red blood cells, is a measure of the dissimilarity of a population of red blood cells by volume, and indicates deviations in the volume of red blood cells. The coefficient is adopted as an auxiliary criterion for diagnosing anemia.

RDW SD and RDW CV: transcripts, norm, differences

With the decoding of RDW in a blood test, the situation has cleared up a bit, but this is just the tip of the iceberg. There are two measures of RDW. These are RDW-CV and RDW-SD - they both determine the variability of red blood cells in size.

The first index stands for the relative width of the distribution of erythrocytes by volume (coefficient of variation). RDW-CV in a blood test is affected by MCV, with fluctuations of which there will be a tendency to increase the described indicator. To make it clearer, look at the calculation formula:

RDW-CV=SD/MCV 100

Here, SD acts as the standard deviation of RBC volume from the mean. The RDW-CV index indicates how much the red cell volume differs from the average. It is measured as a percentage, normally it counts 11,5%-14,5% , which indicates the existence of a homogeneous population of cells (normo-, micro- or macrocytes).

The erythrocyte coefficient RDW-SD in a blood test stands for the relative width of the distribution of erythrocytes by volume (standard deviation). It shows how different these cells are in size and volume, that is, what is the difference between a tiny erythrocyte and a very large one. This calculated indicator is not subject to MCV, it is measured in femtoliters (fl). His norm is 42±5 fl.

If we consider the differences in these two variants of RDW, then it should be said that RDW-SD is considered a more accurate index in the presence of a small population of macrocytes (erythrocytes with a diameter greater than 7.9 μm) or microcytes (diameter

RDW in the blood test is elevated

An increase in RDW by more than 15% indicates the presence of cells that are heterogeneous in volume (micro-, normo-, macro- and schizocytes). The higher the score, the greater the discrepancy in the size of the red cells. This phenomenon is called anisocytosis. The width of the distribution of erythrocytes above the norm can be the result of many reasons, which include:

• microcytic anemia;
• blood transfusions;
• Iron-deficiency anemia;
• oncopathology with metastases to the bone marrow;
• folic acid deficiency;
• alcoholism;
• myelodysplastic syndrome.

An increased width of the distribution of erythrocytes is also observed with chronic lesions liver (against the background of normal MCV), lead poisoning, Alzheimer's disease, microspherocytosis, hemoglobinopathies, bone marrow metaplasia, as well as cardiovascular diseases.

RDW in the blood test is lowered

If in the analysis the width of the distribution of erythrocytes is below the norm, then this fact indicates the need to retake the tests. Because the analyzer shows either an overestimated value or a normal value. In principle, the distribution width of erythrocytes cannot be reduced, and such a result is not diagnostically valuable.

One of important factors when conducting a complete blood count is the distribution index of erythrocytes (RDW). This is an indicator determines the shape and size of red blood cells. These red blood cells carry out a transport function, helping to deliver oxygen to all tissues and organs, taking away carbon dioxide and toxins accumulated by cells. Normally, their sizes are approximately the same, which allows for certain conditions they quickly stick together, forming blood clots.

red blood cells can indicate the presence of pathologies in the body, especially if their dimensions are very different from each other. In what cases the distribution index is lowered, what this indicates and how it manifests itself, we will find out further.

At healthy person erythrocytes have the same shape, density and color. In cases of deviations, especially when autoimmune diseases and oncology, there is a failure at the microcellular level, when newly formed cells receive less certain components, and in fact are not able to perform their functions. This is where anemia develops. pathological condition in which the body does not receive right amount oxygen, that is, the metabolic function of erythrocytes is disturbed.

The distribution index of erythrocytes is determined when conducting. In some cases, if a specific disease is suspected, only this index can be determined in the analysis. In most cases, the width of the RDW is determined together with, since these indices (by volume and number) are interconnected and help determine the type of anemia. The fact is that for a complete assessment of the state of erythrocytes, not only their shape is important, but also their quantity in the blood. And if increased rates occur with a frequency of 1 per 10,000 people, then reduced values ​​\u200b\u200bare extremely rare and always indicate serious problems with health.

A blood test for the determination of RDW can be performed both routinely (during medical examinations) and according to indications, when there are suspicions of abnormalities in the hematopoietic function. AT without fail analysis is performed before surgery, in childhood and during pregnancy.

Why is RDW needed?

As mentioned above, this index allows you to evaluate qualitative composition erythrocytes, given their size.

But what does it give? The point is that e red blood cells are similar to each other like twin brothers, which allows them to replace each other at the right time or stick together into blastulae. If the cells increase in size, their need for nutrition also increases, respectively, their life expectancy is short. This in turn affects general level erythrocytes in the blood and human health.

The more cells die, the more iron is released, which in turn represents increased load on the liver, which will malfunction, unable to cope with the processing of these substances.

Ask your question to the doctor of clinical laboratory diagnostics

Anna Poniaeva. Graduated from the Nizhny Novgorod medical academy(2007-2014) and residency in clinical laboratory diagnostics (2014-2016).

The RDW index is directly related to anisocytosis - pathological process, in which the shape of red blood cells is modified, which affects their volume and size. Anisocytosis is a complex chemical process, as a result of which all blood cells are affected.

We suggest watching a video on the topic

How is it determined?

The distribution index of erythrocytes is calculated as a percentage, the norm of which varies from 11.5 to 14.8.

Determined using mathematical formula, in the form of a ratio of modified erythrocytes exceeding the maximum allowable volumes to total mass erythrocytes.

To date, laboratories use computer technology to determine the percentage of deviation from the norm, without doing manual calculations. Output presented as a histogram, which displays a curve indicating possible modifications of red blood cells.

What do the results depend on?

Norms are determined, depending on age, gender and availability physiological processes occurring in the body. For children of the first year of life, an indicator of 11.5-18.7% is considered the norm. After a year, the digital values ​​tend to the generally accepted norm - 11.5-14.5%. In women, the upper limit can shift up to 15.5%, which is explained by frequent changes hormonal background: pregnancy, breastfeeding, hormonal contraceptives, climax.

The blood is taken into morning time(before 9 am) on an empty stomach. It is important that a person does not take any medications before taking blood, and is also in a balanced state.

Index variations

With a more detailed in-depth study of the indicator of the index of distribution of erythrocytes consider two quantities:

1. RDW-SD - defines the standard deviation from the norm, expressed in femtoliters. The indicator has nothing to do with MCV, since it shows the quantitative value of the difference between the largest and smallest cells.
2. RDW-SV - shows how much the volume of erythrocytes differs from the average. It is defined as the percentage of all deformed cells to the total erythrocyte mass.

What do the low values ​​mean?

Since it is impossible to fully evaluate RDW without MCV, all options should be considered. reduced values with the relationship of these two indices:

1. RDW is low and MCV is below average - a problem with the liver and spleen.
2. RDW is low and MCV is above normal - presence oncological diseases predominantly with bone marrow metastases.

A decrease in the distribution of erythrocytes cannot be manifested in principle, if we consider this indicator from a biological point of view. Therefore, in medical practice quite low values in 99.9% of all cases, the patient is offered to retake blood, having previously fulfilled all the conditions:

• do not smoke or drink alcohol 24 hours before blood sampling;
• do not use medications before analysis;
• limit the intake of salty and smoked foods the day before.

In the case when the RDW is really below the norm, which is confirmed by the unsatisfactory analyzes of his "colleague" MCV, this may indicate the development of such diseases, how:

1. Microcytic anemia - in the common people "anemia", when, due to irregular shapes, red blood cells quickly die off, without representing any biological value for the body.
2. Malignant neoplasms - usually refers to diseases such as mastopathy, bone marrow cancer and lung cancer.
3. Extensive hemolysis is a process in which red blood cells are destroyed before they reach their target. As a result, active hemoglobin is released.

The reasons

There are a number of reasons that could provoke the development of such a manifestation, as a reduced RDW:

1. Large blood loss in traumatism and pathological bleeding. The most dangerous are uterine and gastric internal bleeding, in which blood leaves at a rapid pace, reducing the chances of survival.
2. Frequent surgical interventions, especially when removing any organ or part of it.
3. Incorrect metabolism, in which the food consumed is not completely digested and assimilated, but partially or completely undergoes fermentation and decay processes.
4. Hormonal imbalance, which is more common among the female half of the population.
5. Lack of iron and B vitamins in the body.
6. Pathologies of the blood, which are characterized by rapid destructive processes, as a result of which erythrocytes completely lose their biological functions.

How is it manifested?

A patient with a low RDW will have all the symptoms of anemia:

• fast fatiguability;
• frequent dizziness, especially with sudden movements;
• constant fatigue even after a long rest;
• severe shortness of breath with the addition of chest dry cough for no reason;
• increased heart rate (tachycardia);
• promotion blood pressure(if overweight).

Such clinical manifestations easy enough to explain. Small cells bring less oxygen to tissues and organs, from which the latter begin to suffer, since all natural biological processes(oxidation and reduction) do not occur without oxygen. Large ones are generally not able to retain oxygen molecules on their surface, from which microcytic anemia develops.

The first to suffer nerve cells, responsible for all impulses in the body, from where the above symptoms appear.

What to do?

At a consultation with a doctor, most likely he will ask to retake the analysis, since the distribution index of erythrocytes is practically never lowered. This means that all cells are ideal in their parameters, which cannot be in principle. If all factors that could affect the inaccuracy of the results are excluded and the indicator is repeated, the full examination body, with particular attention to oncological research.

Prevention

prevent this process You can follow these simple rules:

1. Eat a balanced diet, including plenty fresh vegetables, fruits and lean meats.
2. Be outdoors more often.
3. News active image life.
4. Do not neglect scheduled medical examinations, where, according to statistics, most often serious pathologies without external signs.

Thus, the distribution index of erythrocytes shows their size relative to each other, which makes it possible to determine their biological value. Reduced rates are extremely rare, but can fully indicate the presence of various diseases. The index is determined when general analysis blood, but it has full strength only when combined with the MCV index, the indicators of which are interconnected.

This percentage is relative, so in many cases it is not calculated with a detailed blood test.

A blood test can determine not only the quantitative, but also the qualitative composition of the blood. The size, shape, color and volume of cells are additional criterion for diagnosing diseases. Sometimes in the general analysis, in addition to red, white, flat cells RDW is indicated, which means the distribution of red blood cells in width.

What is RDW in a blood test?

The color of our blood is given by red cells - erythrocytes. They are disc-shaped, concave in the middle on both sides. They are produced by the red bone marrow. The composition of cells contains hemoglobin - a protein that takes part in metabolism. It binds oxygen in the lungs, then delivers it to the tissues.

Normally, all red blood cells have same size, shape, color, so that, if necessary, one cell can replace another and perform the same functions. At various diseases part of the erythrocytes increases in size. large cells cannot pass into the narrow lumen of the capillaries, blood circulation is disturbed, so the body utilizes unnecessary elements.

RDW is an index that shows the ratio of healthy and enlarged red blood cells by diameter. 2 RDW indicators are determined:

• RDW CV is the distribution of erythrocytes by size in percent;
• RDW SD - determines the difference between the smallest and largest red blood cells.

For the RDW standard, red cells of medium size and volume are taken: normocytes with a diameter of 7-7.5 microns. The indicator is measured in femtoliters - this is the proportion of volume in relation to a liter.

Analysis on RDW

Analysis for RDW shows erythrocyte anisocytosis, that is, the presence of red cells of a non-standard size. In addition to normocytes in anisocytosis, there are:

• Microcytes - their diameter is less than 7 microns;
• Macrocytes - diameter from 8 to 12 microns;
• Megalocytes - more than 12 microns.

When RBCs are very different in size from normocytes, anisocytosis is diagnosed. Depending on which cells predominate, microcytosis, macrocytosis, and a mixed state occur.

RDW is defined in general clinical analysis, which is held in planned during diagnosis or before surgery.

The value of the indicator needs to be known if anemia is suspected, differential diagnosis various kinds diseases, as well as to control the quality of treatment.

Blood is taken from a finger in the morning on an empty stomach. In the laboratory, the degree of decrease or increase in RDW is calculated. The laboratory assistant can do this manually or on a modern hematological analyzer. On the device, the study shows more exact values, the result is determined faster.

When the level of anisocytosis is elevated, a retake for analysis with a histogram is required, since the width of the distribution of erythrocytes changes frequently and quickly.

Norm RDW in a blood test

The normal RDW value does not depend on age and sex differences in adults. In newborns and older children, this figure may normally be slightly higher than in adults.

RDW rate table in percent:

There are several degrees of anisocytosis:

• I degree - a slight increase, large and small red blood cells are in the range of 30-50%;
• II degree - moderate increase: from 50% to 70%;
• III degree - a pronounced increase in anisocytosis: more than 70%;
• IV degree - almost all erythrocytes are changed.

Analyzers count the number of red cells different size per 1 µl of blood, as well as a deviation in size by degrees. In addition to RDW - the width of the spread of erythrocytes in diameter, - a study is used on MCV - the distribution of red cells by volume. Knowledge of the second indicator is necessary for a more accurate diagnosis.

Increased RDW

Raising the RDW index from normal value indicates that diseases are present in the body. If the distribution width of red blood cells is increased, this means that most of red bodies was deformed and changed. The life span of such cells is reduced, which affects the total number of red blood cells in the body: the indicator goes down.

RDW is elevated in a blood test for the following diseases:

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A change in the distribution of red cells along the diameter may also indicate cardiovascular pathology and development of IB of the heart.

With quality and timely treatment the distribution index of erythrocytes increases, as many young erythrocytes of normal diameter appear.

RDW in the blood test is lowered

A decrease in the width of the distribution of erythrocytes below the norm practically does not occur. With some types of anemia, it can remain within normal values:

• Aplastic anemia - stem cells of the bone marrow are affected, because of this, blood cells do not mature and grow;
• Posthemorrhagic anemia - after bleeding;
• Anemia in chronic diseases;
• Spherocytosis - red cells take the form of a ball and quickly collapse (a type of hemolytic anemia);
• Thalassemia - hereditary disease, in which erythrocytes are deformed, it is dangerous to develop a hemolytic crisis;
• Sickle cell anemia - genetic disease blood, a defect in cells does not allow binding hemoglobin in full, the cells are elongated in shape and resemble a sickle, which is fraught with blockage of blood vessels throughout the body.

Since there are a great many different types of anemia, in medicine index RDW plays essential role for diagnosing diseases. The indicator is also determined to monitor the effectiveness of treatment in order to make changes to the treatment if necessary. medical measures without allowing complications and serious consequences.