ANAEMIA

ANAEMIA

Susmita Majumder¹, Poonam Yadav¹, Santanu Nath²

1. Division of Physiology & Climatology, ICAR-IVRI Bareilly (U.P.)
2. Division of Livestock Products Technology, ICAR-IVRI Bareilly (U.P.)

Anemia is a condition in which hemoglobin (Hb) concentration and/or red blood cell (RBC) numbers are lower than normal and insufficient to meet an individual’s physiological needs due to reduced oxygen flow to the body’s organs. Anaemia is also defined as an absolute decrease in the red cell mass as measured by RBC count, hemoglobin concentration, and/or PCV. It can develop from loss, destruction, or lack of production of RBCs.

Animals with anaemia often present with pale mucous membranes – the first step is therefore to differentiate those animals with pale mucous membranes due to poor peripheral perfusion (i.e. hypovolemic, cardiogenic or obstructive shock) and those who have a reduced red blood cell mass.

TYPES OF ANAEMIA:

There are several types and classifications of anaemia. The occurrence of anaemia is due to the various red cell defects such as-

•  Production defect (aplastic anaemia), maturation defect (megaloblastic anaemia)
• Defects in haemoglobin synthesis (iron deficiency anaemia)
• Genetic defects of haemoglobin maturation (thalassaemia)
• Due to the synthesis of abnormal haemoglobin (haemoglobinopathies, sickle cell anaemia and thalassaemia)
• Physical loss of red cells (haemolytic anaemia)

Sickle cell anaemia

It is inherited disease, in which the body makes sickle-shaped (“C”-shaped) red blood cells is called sickle cell anaemia. It contains abnormal haemoglobin which causes sickle shape and can’t move easily through the blood vessels. Sickle cells usually die after about 10 to 20 days and the body can’t reproduce red blood cells fast enough to replace the dying ones, which causes anaemia.

Thalassaemia

Thalassaemia is an inherited blood disorder which cause the body to make fewer healthy red blood cells and less haemoglobin. The two major types of thalassaemia are alpha- and beta thalassaemia. The most severe form of alpha thalassaemia is known as alpha thalassaemia major, while the severe form of beta thalassaemia is known as thalassaemia major or Cooley’s anaemia. Thalassaemias are passed on from parents to their children through genes.

CLASSIFICATION OF ANAEMIA

• Etiological Classification / Based on mechanism
• Morphological classification

ETIOLOGICAL CLASSIFICATION / BASED ON MECHANISM

A) Hypoproliferative anaemia: Decreased production of red blood cell. It is again divided into 5 types-

• i) Aplastic anaemia: Aplastic anaemia is a condition that occurs when bone marrow stops producing enough new blood cells due to any disease condition in the body.
• ii) Myelodysplastic syndrome

iii) Nutritional deficiency anaemia: It is occur due to deficiency of iron, which called iron deficiency anaemia. Megaloblastic anaemia also comes under nutritional deficiency anaemia, which cause due to deficiency of vitamin B12/folate.

• iv) Anaemia of chronic disease:g. Rheumatoid arthritis, Hodgkin’s lymphoma, chronic infection, neoplasia
• v) Erythropoietin underproduction
• B) Haemorrhage/Blood loss: Due to haemorrhage or excessive blood loss anaemia occurs.
• C) Regenarative/Hemolytic anaemia: Due to increase destruction of Red blood cell. It is divided into 2 types-
• i) Immune mediated hemolytic anaemia: Occur due to extra-corpuscular defects.
• ii) Non-Immune mediated hemolytic anaemia: It is occur due to intra-corpuscular defects.

MORPHOLOGICAL CLASSIFICATION

Based on morphology (size and shape) of RBC mainly 3 types of anaemia is recorded-

• Microcytic Anaemia (MCV < 82 fL): Microcytic Anaemia happens when red blood cellsare smaller than usual because they don’t have enough hemoglobin.
• Normocytic Anaemia (MCV = 82-98 fL): Happens when fewer red blood cells are present in the body compare to normal condition of the body, and those blood cells have less amount of the hemoglobin than the  normal body condition.
• Macrocytic Anaemia (MCV > 98 fL): Macrocytic Anaemia is a blood disorder that happens when your bone marrow produces abnormally large red blood cells.

CAUSES OF ANAEMIA

The most common cause of anemia is low levels of iron in the body. This type of anemia is called iron-deficiency anemia. Normally body needs a certain amount of iron to make hemoglobin, the substance that moves oxygen throughout the body. However, iron-deficiency anaemia is just one type. Other types are caused by:

• Diets lacking in vitamin B12, or difficulty in use or absorb Vitamin B12 (like pernicious anemia).
• Diets lacking in folic acid, also called folate, or unable to use folic acid correctly (like folate-deficiency anemia).
• Inherited blood disorders (like sickle cell anemia or thalassemia).
• Conditions that cause red blood cells to break down too fast (like hemolytic anemia).
• Chronic conditions causing animal to not have enough hormones to create red blood cells. These include hyperthyroidism, hypothyroidism, advanced kidney disease, lupus and other long-term diseases.
• Blood loss related to other conditions such as ulcers, hemorrhoids or gastritis.

CLINICAL FINDINGS

Anaemia causes tissue hypoxia and triggers compensating mechanisms. Both processes together produce the signs and symptoms characteristics of anaemic syndrome. Clinical signs in anaemic animals depend on the degree of anaemia, the duration (acute or chronic), and the underlying cause. Acute anemia can result in shock and even death if more than one-third of the blood volume is lost rapidly and not replaced. Patients with anaemia may present with fatigue, dizziness and dyspnea; however, mild anaemia shows few clinical signs or symptoms. The sings of anaemia include pallor of the conjunctivae, face, nail beds and palmar creases, Tachycardia, Bounding or weak peripheral pulses, Hypotension.

Anaemia is a syndrome, not a disease, and therefore, the etiology must always be investigated and therapy must be directed mainly to the causal disease, and not only to restoring a normal hemoglobin concentration.

CONCLUSION                          

Anaemia is a serious global public health problem. More than 100 diseases may cause anaemia, but 90% belong to three groups: nutritional deficiencies (iron, vitamin B12 and folic acid), ACD (chronic inflammation, tumors), and bleeding (excluding chronic bleeding, which produces iron deficiency). A few laboratory tests, such as blood count, ESR, serum ferritin, and serum iron and transferrin, are sufficient to focus the diagnosis. Diagnosis of anaemia is important for treatment of disease which shows signs of anaemia.

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