{"id":1134,"date":"2018-01-15T14:25:58","date_gmt":"2018-01-15T14:25:58","guid":{"rendered":"https:\/\/emedicalupdates.com\/?p=1134"},"modified":"2022-01-12T10:44:08","modified_gmt":"2022-01-12T10:44:08","slug":"red-blood-cell-indices","status":"publish","type":"post","link":"https:\/\/emedicalupdates.com\/red-blood-cell-indices\/","title":{"rendered":"Red Blood Cell Indices"},"content":{"rendered":"
Most of us have seen blood check reports which show various values indicating changes in many health conditions. Though it is difficult for a non-medical person to understand their implications, most are able to compare the results with the normal values.<\/p>\n
Certain indices of red blood cells had always been a part of the report which many people do not understand at all. In this article, we are trying to simplify those red blood cell indices for an easier understanding and knowledge.<\/p>\n
In order to grasp the complete sense of indices such as MCV, MCH, MCHC etc, it is of utmost importance to have a general idea about blood and its components.<\/p>\n
Blood, as everyone knows, is the fluid that circulates throughout the body due to the pumping action of heart. The main functions of blood include carrying nutrition to the tissues, removing the toxic and unwanted materials from tissues and transport of oxygen to and carbon dioxide from the tissues.<\/p>\n
Lot of other functions are also carried out in the body by our blood. It has various components which helps it to complete these functions effectively.<\/p>\n
On an average, an adult has approximately 5 litres of blood that circulates within the blood vessels of the body (1<\/strong>)<\/sup>. This volume is regulated by the kidneys. The volume of blood in a person varies in different age group and between male and female genders. To understand the composition of blood, it is easier to consider it as a liquid portion and the cellular portion.<\/p>\n The liquid part of blood is known as plasma which constitutes about 55% of the blood volume (2<\/strong>)<\/sup>. Remaining 45% is made up by the blood cells. Plasma is approximately 92% water and rest includes suspended particles such as proteins, minerals, electrolytes, hormones etc (3<\/strong>)<\/sup>.<\/p>\n The cellular portion of the blood includes Erythrocytes (Red blood cells\/RBC), Leucocytes (White blood cells\/WBC) and Thrombocytes (Platelets). There are about 4.7- 6.1 million RBCs per microliter of blood in males and about 4.2 \u2013 5.4 million RBCs per microliter of blood in females (4<\/strong>)<\/sup>.<\/p>\n In addition there are about 4,000- 11,000 WBCs and 200,000- 500,000 platelets per microliter of blood (5<\/strong>)<\/sup>.<\/p>\n <\/p>\n Picture 1: An image showing content of blood. They are the most abundant cells in the blood. This is because they carry out one of the major functions of the blood, oxygen and carbon dioxide transportation. To facilitate this function, RBC has a biconcave (both the surfaces are concave) oval disc shape, that allows it to bend, twist or change shape while passing through narrow passages.<\/p>\n On a cross section, they appear more like a dumbbell because of its central depression on both the surfaces. In the early stages of its development (erythropoiesis), RBC has nucleus which the cell loses as it matures.<\/p>\n This process helps in giving more space for accommodation of haemoglobin. (6<\/strong>)<\/sup><\/p>\n <\/p>\n Picture 2: RBCs in blood. Table 1: General features of a mature RBC.<\/strong><\/em><\/p>\n When a complete blood count is advised, the following tests related to RBCs are done.<\/p>\n RBC count, Hematocrit\/ Packed cell volume (PCV), Hemoglobin (Hb), Mean corpuscular Volume (MCV), Mean corpuscular haemoglobin (MCH), Mean corpuscular haemoglobin concentration (MCHC), RDW, Reticulocyte count.<\/p>\n Hemoglobin content of RBC is what decides the oxygen carrying capacity of blood. Structurally it is made up of iron and a protein (globin). At the same time, the red colour of blood is due to Hb. It becomes bright red when oxygenated and dark red when deoxygenated (13<\/strong>)<\/sup>.<\/p>\n The normal levels of Hb in Male are about 13.8- 18.0 g\/dL and in Female are about 12.1- 15.1 g\/dL (14<\/strong>)<\/sup>. When the hemoglobin content reduces in the blood, the condition is called as Anemia. Conversely, when it increases above the normal range, polycythemia ensues.<\/p>\n Anemia can be explained by decrease in hemoglobin levels, haematocrit values or RBC count (15<\/strong>)<\/sup>.<\/p>\n RBC count is generally measured as number of cells per micro litre of blood. It is seen that the count decreases in anemia and increases in polycythemia.<\/p>\n <\/p>\n <\/p>\n Picture 3: An image showing the Hematocrit assessment. The bottom part showing RBCs forms the hematocrit. PCV is another component of a complete blood count, which indicates the RBC component of the blood in percentage. The normal value of PCV in men is about 42% to 50% and in women it is about 36% to 45% (16<\/strong>)<\/sup>. As seen above, it is noted that the haematocrit values decrease in anemia and increase in polycythemia.<\/p>\n Hematocrit is nowadays measured by an automated blood analyser. Imagine that RBCs are stacked together. The volume of these cells together can be calculated by volume of one cell multiplied by the number of RBCs, which is Mean Corpuscular Volume (MCV) multiplied with the total count of RBCs (17<\/strong>)<\/sup>.<\/p>\n Another method of finding hematocrit values is by using differential spectrophotometry (18<\/strong>)<\/sup>.<\/p>\n Certain condition where the fluid portion of blood is decreased, the hematocrit is increased. When oxygen in blood is less, body tries to make more RBCs which will lead to a rise in hematocrit (19<\/strong>)<\/sup>.<\/p>\n Table 2: Showing causes of increased or decreased hematocrit.<\/strong><\/em><\/p>\n Now we know the average size of an RBC and the hemoglobin content in each RBC. To check if these values are normal in a person, we need to have a little more detailed information from his or her blood. These details are called RBC indices.<\/p>\n They are Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), RBC Distribution Width (RDW) and Reticulocyte count. Usually first three of them are done whenever a complete Blood Count is requested to a diagnostic centre.<\/p>\n Many diagnostic labs do not do RDW and Reticulocyte count. With the modern facilities, most of the centres now give a report with all these details as all of them are done by an automated blood analyser.<\/p>\n As we have seen before, hemoglobin inside the RBC is responsible for the transport of oxygen to the tissues. When oxygen is not delivered sufficiently, the cell health will be affected. This can happen in anemia where the hemoglobin levels or RBC counts have decreased.<\/p>\n To identify the type of anemia and its effect on RBCs, we will have to know about the RBC indices.<\/p>\n Anemia can be defined as a decrease in hemoglobin levels or RBC count or hematocrit values below the normal range (15<\/strong>)<\/sup>.<\/p>\n <\/p>\n Picture 4: An image depicting a comparison between a normal person\u2019s blood and an anemic person\u2019s blood. Causes of anemia are many and their diagnostic approach is also different. In general, there are a few causes that can be remembered easily.(15<\/strong>)<\/sup><\/p>\n Symptoms of anemia develop over a time in case of slowly developing anemia, or may be sudden in case of severe blood loss leading to hypovolemia (reduced blood volume). (15<\/strong>)<\/sup><\/p>\n When the anemia has caused decreased oxygen delivery to the tissues it can cause<\/p>\n In hypovolemia, anemia may lead to tiredness, muscle cramps, dizziness while changing position, hypotension (decreased blood pressure), shock and even death.<\/p>\n <\/p>\n Picture 5: Symptoms of Anemia Diagnosis of anemia involves multiple steps to identify the cause and type of anemia. This include doing a complete blood count with RBC indices, a peripheral smear to visualize the size and shape of RBCs, evaluation of iron content of blood and iron carrying capacity of blood and bone marrow studies (15<\/strong>)<\/sup>.<\/p>\n The importance of RBC indices in diagnosis of anemia can be understood from the details given till now. Let us look at them individually to understand what they are and how it helps.<\/p>\n If the volume of whole RBCs along with the number of RBCs is known, it is easy to find the average volume or size of a single RBC. This is the concept used to measure MCV in an automated analyser.<\/p>\n The issue with looking at only MCV is that it may be insufficient to identify if there are both large and small RBCs. This is because the value is just an average and may show a result which is normal. Other indices will help to identify such an issue, if it occurs (26<\/strong>)<\/sup>.<\/p>\n Normal MCV- 80-96<\/span> fL <\/strong>(16<\/strong>)<\/sup><\/em><\/p>\n<\/blockquote>\n The MCV can be lower or higher than the normal values in abnormal conditions. When it falls below 80 fL, the RBCs can be classified as microcytic. \u2018Micro\u2019 means smaller and \u2018cytic\u2019 is related to cell. Therefore, when the volume has decreased, it indicates that the cell size has decreased.<\/p>\n Conversely, if the MCV is elevated above 100 fL, it can be diagnosed as macrocytic. These variations in size are normally seen when there is anemia.(15, 25<\/strong>)<\/sup><\/p>\n When the RBC size is decreased, the hemoglobin content of the RBC also decreases. This is demonstrated by a decreased MCH (Mean Corpuscular Hemoglobin). As we know that the hemoglobin is what gives colour to the RBC, when it decreases we call it hypochromic.<\/p>\n In general, when MCV and MCH decrease, we can diagnose microcytic hypochromic anemia.(15<\/strong>)<\/sup><\/p>\n <\/p>\n Picture 6: Peripheral smear.
\nImage Source: www.alhijamah.com<\/p>\nErythrocyte (Red Blood Cell\/ RBC)<\/h2>\n
\nPhoto Source: www.fi.edu<\/p>\n\n\n
\n Total count of RBC<\/span><\/td>\n 20-30 Trillion (7<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Male<\/span><\/td>\n 4.7- 6.1 million\/\u00b5L of blood (4<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Female<\/span><\/td>\n 4.2 \u2013 5.4 million\/ \u00b5L of blood (4<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Nucleus<\/span><\/td>\n Absent (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Golgi apparatus<\/span><\/td>\n Absent (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Mitochondria<\/span><\/td>\n Absent (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Endoplasmic reticulum<\/span><\/td>\n Absent (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Life span<\/span><\/td>\n 100-120 days (8<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Time taken for one complete circulation in the body<\/span><\/td>\n Approximately 60 seconds (8, 9, 10<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Diameter<\/span><\/td>\n 6.2-8.2 \u00b5m (11<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Thickness at the peripheral part<\/span><\/td>\n 2- 2.5 \u00b5m (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Thickness at the centre<\/span><\/td>\n 0.8- 1 \u00b5m (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Average volume<\/span><\/td>\n 90 fL (12<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Volume when swollen up with non-distended membrane<\/span><\/td>\n up to 150 fL (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Surface area<\/span><\/td>\n 136 \u00b5m2 (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Hemoglobin content in each RBC<\/span><\/td>\n Approximately 270 million molecule\/RBC (6<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Hemoglobin (Hb)<\/h2>\n
RBC Count<\/h2>\n
Hematocrit\/ Packed cell volume (PCV)<\/h2>\n
\nImage Source: image3.slideserve.com<\/p>\nCauses of increased or decreased hematocrit<\/h3>\n
\n\n
\n Increased hematocrit<\/strong><\/span><\/td>\n Decreased hematocrit<\/strong><\/span><\/td>\n<\/tr>\n \n Dehydration (20<\/strong>)<\/sup><\/span><\/td>\n Anemia (17<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Decreased plasma level (17<\/strong>)<\/sup><\/span><\/td>\n Pregnancy (17<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Dengue fever with Dengue Shock Syndrome (17<\/strong>)<\/sup><\/span><\/td>\n Acute myeloid leukemia (17<\/strong>)<\/sup><\/span><\/td>\n<\/tr>\n \n Polycythemia vera (17<\/strong>)<\/sup><\/span><\/td>\n \u00a0<\/span><\/td>\n<\/tr>\n \n Chronic Obstructive Pulmonary Disease (COPD) (17<\/strong>)<\/sup><\/span><\/td>\n <\/td>\n<\/tr>\n \n Capillary leak syndrome (17<\/strong>)<\/sup><\/span><\/td>\n <\/td>\n<\/tr>\n \n Staying in high altitudes for longer time (19<\/strong>)<\/sup>.<\/span><\/td>\n <\/td>\n<\/tr>\n \n Drugs- Anabolic steroids such as Oxymetholone, Boldenone. (17<\/strong>)<\/sup><\/span><\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n RBC Indices<\/h2>\n
Why do we need to know RBC indices?<\/h2>\n
What is Anemia?<\/h2>\n
\nPhoto Source: www.petmd.com<\/p>\nWhat are the causes of Anemia?<\/h2>\n
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What are the symptoms of Anemia?<\/h2>\n
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\nImage Source: im.rediff.com<\/p>\nHow is Anemia diagnosed?<\/h2>\n
<\/h2>\n
Mean Corpuscular Volume (MCV)<\/h2>\n
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Variations in MCV<\/h3>\n
Microcytic anemia<\/span><\/h3>\n
\nPhoto Source: 5minuteconsult.com<\/p>\nCauses of Microcytic Hypochromic anemia<\/h3>\n
\n\n
\n CAUSE<\/strong><\/span><\/td>\n DUE TO<\/strong><\/span><\/td>\n<\/tr>\n \n Iron deficiency (15<\/strong>)<\/sup><\/span><\/td>\n Decreased iron availability<\/span><\/td>\n<\/tr>\n