Contents
- Blood functions
- Anisocytosis: what blood parameters are paid attention to
- Clinical value of the RDW index in the correct diagnosis
- RDW-CV – what is it?
- RDW-CV – morfologia
- RDW-CV and RDW-SD – what’s the difference
- RDW CV – normal
- RDW-CV – indications
- Low RDW-CV
- High RDW-CV
- RDW-CV – how to lower?
- RDW-CV in children
- RDW-CV in pregnancy
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Blood count is the basic test and abnormal results can signal a variety of diseases. RDW-CV is a parameter that indicates the variation in the volume of red blood cells. A high test result indicates anemia caused by iron deficiency or severe hemorrhages.
Often, patients who donate blood to the laboratory for analysis seek an explanation of the finished result. This situation is popular, because instead of several columns, people see a list of 18 to 22 parameters as a result. Our article will help to understand this issue.
Blood functions
Blood is the most important indicator by which the state of the body can be assessed. It is a liquid medium, which includes plasma and formed elements: platelets, erythrocytes and leukocytes.
Erythrocytes are red corpuscles, the shape of which resembles a concave disk. These are cells without nuclei. Their size varies from 7.5 to 8.3 microns, and live from 3 to 4 months. Erythrocytes have antigenic properties, on the basis of which there are 4 blood groups.
In the blood, in addition to mature erythrocytes, young blood cells can be found. Such cells do not have nuclei and contain a large amount of RNA and ribosomes. They have membrane receptors for transferrin. Reticulocytes lose their RNA and the ability to produce hemoglobin when they become mature cells.
The circulatory system in the body is very important. Since such an environment provides nutrition to organs and tissues, a complete blood count is required constantly. During the study, the color, size and shape of blood cells are taken into account. Changes in shape and size indicate poikilocytosis and anisocytosis occurring in the body.
Anisocytosis: what blood parameters are paid attention to
Specialists of clinical diagnostic laboratories often answer questions regarding the interpretation of hematological analysis indicators. An automatic analyzer allows you to get an accurate result, indicating the state of the human body.
At meetings of laboratory assistants, the following question is often asked: “ What indicators of the hematological analyzer allow us to analyze the clinical picture of the patient? “.
Let us examine these aspects using the example of interpreting the values of the RDW-SD and RDW-CV indicators in the diagnosis of anisocytosis.
Anisocytosis is a disease in which there is an increase in the number of cells of non-standard sizes. Depending on which bodies have changed in size, there is anisocytosis of platelets and erythrocytes.
Anisocytosis of erythrocytes in a general blood test indicates that the size of red blood cells has deviated from the standard. Normally, their value is from 7.5 to 8.3 microns. Red blood cells may be present in the blood, the size of which deviates, but their number should not exceed 30%. According to medical research, it is acceptable when 15% of cells are more than normal, 15% are less than normal. Red blood cells with a diameter of 6.9 microns are called microcytes.
Large cells come in two groups: macrocytes (which vary in size from 8 to 12 microns) and megalocytes with a diameter of more than 12 microns.
If, according to the results of the study, bodies are found in the hematological analyzer, the size of which differs significantly from the specified norm, then the diagnosis is made: “ Increased anisocytosis of erythrocytes ”.
Depending on which cell size prevails in the liquid medium, anisocytosis can be of the following types: microcytosis, macrocytosis and mixed type. The latter species is characterized by the presence of bodies of various sizes.
Denote the degree of heterogeneity using a special index RDW, indicating the width of the distribution of red blood cells. Otherwise, such an indicator is called the erythrocyte anisocytosis index. It shows the difference in the size of the cell population in the tested sample.
The following indices exist: RDW-CV and RDW-SD . The first index indicates the percentage distribution of cells by size. The second index is the standard deviation, namely the difference in size between large and small bodies.
RDW-CV is determined using a hematology analyzer. The device counts the number of bodies automatically. The result obtained is expressed as a percentage. The index is normal if its value is from 11 to 15%.
As a result of blood, another RDW-CV index can also be found, which is determined by a different method. It is measured in femtoliters. It represents the difference between the minimum and maximum cell volume in the test sample. The normal value is from 35 to 60 femtoliters.
Clinical value of the RDW index in the correct diagnosis
The RWD value is interpreted at the same time, estimating the average volume of erythrocytes. This is due to the fact that the width of the distribution of erythrocytes does not deviate from the norm during microcytosis and macrocytosis.
If the indicator is exceeded, we can talk about the development of the patient:
- iron deficiency anemia;
- Hemolytic or megaloblastic anemia with a lack of B vitamins;
- Hemoglobinopathies.
The rate will be elevated if the patient has liver disease or has recently had a blood transfusion. In the presence of cold agglutinins in the blood, an increase in the index may occur erroneously.
In addition, there are pathological conditions in which the index does not change. These include anemia in severe diseases, spherocytosis, anemia. It is important to pay attention to the fact that in the treatment of iron deficiency anemia, the index does not decrease, but rather increases. This is due to the appearance of new cells, the size of which differs from red blood cells. With the effectiveness of therapy, the anisocytosis index returns to normal.
“Medica-Group” is an online store of laboratory equipment necessary for equipping medical institutions. In the company’s catalog, buyers can purchase bacteriological analyzers and related equipment. The technique examines blood samples and reveals heterogeneity in the size of the red blood cell population.
You can buy on the company’s website various models of analyzers that differ in functionality and technical characteristics. The acquisition of sophisticated medical equipment will provide a clinical diagnostic laboratory of various sizes.
RDW-CV – what is it?
One of the parameters in the blood test is RDW-CV which means In English (red blood cel distribution width, coefficient of variation) the extent of red blood cell size distribution taking into account the variability factor. In other words, the RDW-CV is an indicator of how much single red blood cells differ in volume from a standard.
What is the RDW-CV Score and what does it tell us?First of all, the test is performed when anemia, i.e. anemia, is suspected. The RDW-CV result answers the question of how deep an anemia is this.
An abnormal RDW-CV test result may accompany diseases with a high probability of health hazard. A person is at risk of a heart attack and stroke, and is also at increased risk of developing atherosclerosis. A lower or higher RDW-CV percentage is also a bad sign for patients suffering from chronic lower limb ischemia or diabetes after stroke, myocardial infarction, or diabetes.
Although it is assumed that they measure from 6 to 8 µm, it is important to know that erythrocytes, or red blood cells, in the human body have a naturally different size, which is taken into account in the RDW-CV study. Erythrocytes are divided into:
- microcytes – smaller than 6,0 µm,
- normocytes – from 7,7 to 8,0 µm,
- macrocytes – larger than 9,0 µm,
- megalocytes – larger than 12,0 µm.
RDW-CV – morfologia
The RDW-CV test is performed as part of the blood count. This is a routine analysis worth doing once a year. The test involves taking blood from a vein in the arm. The patient should arrive at the collection point on an empty stomach (eat the last meal the day before, maximum at 19:00). You can drink a glass of water. The RDW-CV result should be ready for the next day.
A referral for a test can be obtained through a safe online visit with your GP. The visit takes place without leaving home.
Due to the fact that the blood count is an analysis of many indicators, a bad RDW-CV result can be confronted with other parameters of the red blood cell system to accurately assess the state of health. Such parameters include:
- MCV – mean erythrocyte volume,
- RBC – total number of erythrocytes,
- HCT – blood cell volume to plasma ratio,
- HGB – hemoglobin concentration,
- MCHC – mean concentration of hemoglobin in the red blood cell,
- MCH – average weight of hemoglobin in the red blood cell,
- RET – total number of reticulocytes.
RDW-CV and RDW-SD – what’s the difference
The RDW blood counts are usually reported on two scores, CV or SD. Both can be found in the lab printout. Difference between RDW-SD to RDW-CV inherent in the unit used.
Both CV and SD rates show differences in the size of individual red blood cells, however, CV is expressed as a percentage and SD in femtoliters (fl).
RDW CV – normal
The deviation from the blood cell volume standard to be shown by the test is specified as a percentage. What is the RDW-CV standard? Regardless of gender, the norm in adults is 11-14 percent. This means that erythrocytes are just to such an extent that they are very similar in volume. If such a result exceeds 14 percent. we are dealing with heterogeneity of red blood cells. An indicator above 15 percent. is referred to as a term ‘anisocytosis’. While wAccording to the RDW-SD indicator, the norm is 80 to 90 fl.
However, before we start interpreting the RDW-CV result, we must remember that the standard may vary depending on the diagnostic method adopted in the laboratory. Therefore, the test printout will contain the standard referred to by the diagnostician and it will be the determinant of the interpretation.
RDW-CV – indications
The RDW-CV blood count should be performed once a year as a preventive measure. This recommendation applies mainly to people with suspected certain diseases related to the circulatory system.
- Anemia, or anemia. It may be iron deficiency anemia, megaloblastic anemia, macrocytic anemia or hemolytic anemia. Anemia symptoms such as dizziness, shortness of breath, constant fatigue, pale skin and mucous membranes, and libido disorders may be indications for performing the RDW-CV test.
- Thalassemia, the so-called Mediterranean anemia, in which quantitative disturbances of homoglobin synthesis occur.
- Kwashiorkor – deficiency of vitamins, proteins and trace elements.
- Hypothyroidism – the RDW-CV in such cases is greater than normal.
Low RDW-CV
When the RDW-CV and RDW-SD decrease after blood counts are performed, a decrease is to be feared. Value lower than 14%. indicates that the difference in erythrocyte volume is slight or completely imperceptible. This in turn means that the test has no diagnostic value and the patient is fine.
Even more so, if the reduced RDW-CV is the only abnormal blood count, the test result can be considered normal.
High RDW-CV
The physician’s anxiety may be increased by increased RDW-CV. What does it mean? First of all, the differentiation of the erythrocyte volume. Blood cells contain both standard-sized and greatly enlarged blood cells.
Causes of the RDW-CV above normal There are many. These include, among others, the occurrence of inflammation, the history of neoplastic diseases, especially tumor metastasis to the bone marrow or recent blood transfusion. In addition, elevated RDW-CV may be associated with myelodysplastic syndrome, myeloid metaplasia or supplementation with vitamin B12 and folic acid.
Very high RDW-CV sources also include haemorrhages, including female genital tract haemorrhages, bleeding of esophageal varices, gastric ulcer, and intestinal malabsorption. Increased RDW-CV may also result from starvation-induced malnutrition as well as viral and bacterial infections.
RDW-CV – how to lower?
When the RDW-CV result shows a significant variation in the size of your red blood cells, please consult your doctor. It will either confirm or rule out anemia based on your complete blood count.
If confirmed, the doctor will recommend taking medications that will help lower the RDW-CV. Most likely, these will be preparations containing substances that the body has so far lacked, i.e. folic acid, iron, ferratin or vitamin B12.
It is also advisable to broaden the diagnosis and look for the causes of anemia. The increased RDW-CV parameter is influenced not only by deficiencies, but also heavy menstruation and internal bleeding or fibroids.
RDW-CV in children
Many mothers also wonder what the RDW-CV result means in a child. In fact, his interpretation is not significantly different from that of adults. The RDW-CV standard in children remains at the level of 11,5 – 14,5 percent. A slight deviation can only be seen in the RDW-SD as the norm is assumed to be 78-98 fl, while in adults it is 80-90 fl. However, this is not the variation affecting the percentage of the RDW-CV.
Increased RDW-CV in a child is in most cases due to iron deficiency. It can even occur in infants. RDW-CV too high in a child should be treated as in adults, i.e. by administering drugs to replace the missing nutrients. An RDW-CV low in a child should not, however, arouse anxiety.
RDW-CV in pregnancy
The morphological examination of pregnant women usually differs from the standard result. However, the RDW-CV parameter itself should not significantly differ from the norm, which is considered to be a result oscillating between 11 and 14%. All the more, RDW-CV low in pregnancy should not worry. As with other people, these are not diagnostic values.
The RDW-CV level can be determined as part of the basic blood and urine test package. By purchasing the package, you can perform a blood count as well as a general urine test.
Conversely, a high RDW-CV should be reviewed by a physician and then lowered with medication. The increase in this parameter is usually due to the intake of folic acid and vitamin B12.
Pregnant women most often have non-standard results by parameters other than RDW-CV:
- HCT (hematocrit) – a reduction of up to 7% is observed. the volume of red blood cells in the plasma,
- HGB – the concentration of hemoglobin in the blood decreases,
- the number of leukocytes (white blood cells) in the plasma increases.