Veterinary Clinical Pathology: Erythrocyte Indices PDF

Veterinary Clinical Pathology SORONGON - TACUD ERYTHROCYTE INDICES Also known as red blood cell indices, are measurements that provide important information about the size, hemoglobin content, and concentration of red blood cells (erythrocytes) in the blood. These indices are calcu...

Veterinary Clinical Pathology SORONGON - TACUD ERYTHROCYTE INDICES Also known as red blood cell indices, are measurements that provide important information about the size, hemoglobin content, and concentration of red blood cells (erythrocytes) in the blood. These indices are calculated from values obtained in a complete blood count (CBC) and are essential in diagnosing and managing various types of anemia and other hematological conditions. ERYTHROCYTE INDICES The key erythrocyte indices are: a. Mean Cell Volume (MCV) b. Mean Corpuscular Hemoglobin Concentration (MCHG) c. Red Cell Distribution Width (RDW) A. MEAN CELL VOLUME (MCV) Measures the average volume (size) of individual red blood cells An MCV test may also be used with other tests to help diagnose or monitor certain blood disorders, including anemia. There are many types of anemia. An MCV test can help diagnose which type of anemia you have. Normo-cytic cells have normal MCV; macrocytic cells have increased MCV; and microcytic cells have low MCV. Normal range of MCV TEST UNITS CANINE FELINE EQUINE BOVINE CAPRINE MCV fL 64-72 40-52 43-55 38-51 16-22 Hematology (Advia 2120) | Cornell University College of Veterinary Medicine These ranges can vary depending on the specific breed and health status of the animal. Increased MCV may be seen in: Regenerative anemia (most common cause) It is when the body is making new red blood cells to replace the ones lost or destroyed, showing that the bone marrow is actively responding to the anemia. Typically due to blood loss (e.g., trauma, parasites) or hemolysis (e.g., immune-mediated diseases). The bone marrow responds by increasing the production of reticulocytes (immature red blood cells) to replace the lost or destroyed red blood cells. Increased MCV may be seen in: FeLV-related non-regenerative macrocytic anemia Caused by FeLV infection impairing the bone marrow's ability to produce new red blood cells. The red blood cells are larger than normal, and there is a lack of a compensatory increase in reticulocytes. Increased MCV may be seen in: Myeloproliferative disease (uncommon cause) A group of disorders where abnormal proliferation of blood cells occurs in the bone marrow, leading to various blood abnormalities, including anemia. Increased MCV may be seen in: Vitamin B12 and/or folate deficiency (uncommon causes) Deficiencies in these vitamins can lead to macrocytic anemia due to impaired DNA synthesis in red blood cells. This is relatively rare compared to other causes. Increased MCV may be seen in: Familial macrocytosis in the poodle (rare) Where the red blood cells are larger than normal due to a genetic predisposition. Decreased MCV may be seen in: Iron deficiency due to chronic blood loss (most common cause). Iron is required for the synthesis. Hemoglobin synthesis is slower and so nuclear generation is delayed. The red cell undergoes extra cell divisions, resulting in the formation of a microcyte Decreased MCV may be seen in: Congenital portosystemic shunts in dogs A portosystemic shunt is an abnormal blood vessel that diverts blood away from the liver, causing liver dysfunction Liver dysfunction can lead to impaired iron utilization and storage, causing microcytic anemia. Smaller red blood cells are produced, which lowers MCV Decreased MCV may be seen in: Familial microcytosis without anaemia in the Akita. This genetic trait leads to the production of smaller red blood cells even in the absence of anemia. The red blood cells are inherently smaller, resulting in a decreased MCV.  The MCV may be measured accurately using automatic haematology instruments or may be calculated as follows: Auto Hematology Analyzer https://macromedph.com/product/auto- hematology-analyzer-bc-30/ B. MEAN CORPUSCULAR HEMOGLOBIN CONCENTRATION (MCHC) The mean cell hemoglobin concentration (MCHC) is the average concentration of Hb in a given volume of packed red cells. It is calculated from the Hb concentration and the Hct.  Low MCHC measurement is known as hypochromia — indicates that you have a lower concentration of hemoglobin in your red blood cells — having less hemoglobin reduces your blood's capacity to carry oxygen to your organs and tissues. Decreased MCHC occurs in: Regenerative anaemias, where the larger, immature red cells and reticulocytes contain relatively less haemoglobin per cell than normal- sized red cells Iron-deficiency anaemia.  High MCHC measurement is known as hyperchromia — It indicates that you have a higher concentration of hemoglobin in your red blood cells — Can increase your chances of developing various health complications such as blood clots. Cause of Elevated MCHC : Spherocytosis - a rare hereditary condition in which the body makes abnormally shaped RBC. Hyperchromic anemia can also occur when RBC abnormally clump together, referred to as RBC agglutination. The MCHC may be calculated as follows: C. RED CELL DISTRIBUTION WIDTH (RDW) An erythrocyte index used to determine the degree of variation in red cell volume. A more sensitive indicator of altered red cell size than the MCV because, for the latter, a relatively large number of cells must have altered size before the mean value is altered. The RDW is increased in cases of regenerative anemia and with iron-deficiency anemia, i.e. it increases when both large and small cells are present. The RDW is the coefficient of variation of the red cell volume distribution and is calculated by the formula: RDW = (SDMCV ÷ MCV) × 100. It is an index of the degree of anisocytosis or variation in size of the erythrocytes.  ANISOCYTOSIS Variation in the size of erythrocytes because of the presence of macrocytes and/ or microcytes among normocytes It is increased when different populations of cells are present. It may occur when substantial numbers of smaller than normal cells are produced, as occurs with iron deficiency, or when substantial numbers of larger than normal cells are produced as occurs when increased numbers of reticulocytes are produced. REFERENCES: Davidson, M. G., Else, R. W., Lumsden, J. H. (1998). BSAVA Manual of Small Animal Clinical Pathology. McPherson, R., Pincus, M. (2015). Clinical Diagnosis and Management by Laboratory Methods Harvey, J. (2001). Atlas of Veterinary Hematology Villiers, E., Ristics, J. (2016). BSAVA Manual of Canine and Feline Clinical Pathology Lippi, G., et al. (2018). Red blood cell distribution width in heart failure: A narrative review. World Journal of Cardiology (WJC)