DEFINITION

CLASSIFICATION OF ANEMIA

Anemia is classified by 2 methods:

1. Morphological classification
2. Etiological classification

1. MORPHOLOGICAL CLASSIFICATION

• Anemia is classified on the basis of morphology of RBC:
• Size
• Color
• Size of RBC is expressed as mean corpuscular volume (MCV).
• Color of RBC depends upon hemoglobin concentration in RBC and is expressed as mean corpuscular hemoglobin concentration (MCHC).
• By this method, anemia is classified into 4 types.

MORPHOLOGICAL CLASSIFICATION OF ANEMIA

2. ETIOLOGICAL CLASSIFICATION

• In this method, anemia is classified by the cause.
• Etiology means study of cause or origin of any disease.
• Anemia is classified into 5 types on the basis of etiology:

1. Hemorrhagic anemia
2. Hemolytic anemia
3. Nutrition deficiency anemia
4. Aplastic anemia
5. Anemia of chronic diseases

1. HEMORRHAGIC ANEMIA

ACUTE HEMORRHAGE

• Acute hemorrhage means sudden loss of large quantity of blood, as in case of accidents.
• RBCs are:
• Normocytic
• Normochromic

CHRONIC HEMORRHAGE

• Chronic hemorrhage refers to loss of blood over a long period of time.
• Blood loss occurs by internal or external bleeding as in conditions such as:
• Peptic ulcer
• Purpura
• Hemophilia
• Menorrhagia
• RBCs are:
• Microcytic
• Hypochromic

2. HEMOLYTIC ANEMIA

A. EXTRINSIC HEMOLYTIC ANEMIA

• This type of anemia is caused by destruction of RBCs by external factors.
• Healthy RBCs are hemolyzed by factors outside the blood cells such as:
• Antibodies
• Chemicals
• Drugs

COMMON CAUSES

1. Liver failure
2. Renal disorder
3. Hypersplenism
4. Burns
5. Infections:
   • Hepatitis
   • Malaria
   • Septicemia
6. Drugs:
   • Penicillin
   • Antimalarial drugs
   • Sulfa drugs
7. Poisoning by:
   • Lead
   • Coal and tar
8. Presence of isoagglutinins like anti-Rh
9. Autoimmune diseases:
   • Autoimmune hemolytic anemia due to:
   • Rheumatoid arthritis
   • Ulcerative colitis

B. INTRINSIC HEMOLYTIC ANEMIA

• This type of anemia is caused by destruction of RBCs due to defective RBCs.
• There is production of unhealthy RBCs which are:
• Short lived
• Destroyed soon
• Intrinsic hemolytic anemia is often inherited.
• It includes:
• Sickle cell anemia
• Thalassemia
• Because of abnormal shape in sickle cell anemia and thalassemia, RBCs become more fragile and susceptible to hemolysis.

SICKLE CELL ANEMIA

• Sickle cell anemia is an inherited blood disorder characterized by sickle-shaped RBCs.
• It occurs when a person inherits 2 abnormal genes:
• One from each parent.
• It is also called:
• Hemoglobin SS disease
• Sickle cell disease
• It is common in people of African origin.

HEMOGLOBIN IN SICKLE CELL ANEMIA

• Hemoglobin becomes abnormal.
• The α-chains are normal.
• The β-chains are abnormal.
• Because of this:
• RBCs attain sickle (crescent) shape.
• RBCs become more fragile.
• This leads to hemolysis.

THALASSEMIA

• Thalassemia is another inherited disorder.
• It is characterized by the presence of abnormal hemoglobin in RBC.
• It is also known as:
• Cooley’s anemia
• Mediterranean anemia
• It is more common in:
• Thailand
• To some extent, Mediterranean countries

TYPES OF THALASSEMIA

1. Alpha thalassemia
2. Beta thalassemia

ALPHA THALASSEMIA

• Alpha thalassemia occurs in:
• Fetal life
• Infancy
• The α-chains are:
• Less
• Absent
• Abnormal
• In adults:
• β-chains are in excess.
• In children:
• γ-chains are in excess.
• This leads to:
• Defective erythropoiesis
• Hemolysis
• Infants may be:
• Stillborn
• May die immediately after birth.

BETA THALASSEMIA

• In β-thalassemia:
• β-chains are less in number, absent or abnormal.
• There is an excess of α-chains.
• The α-chains precipitate.
• This causes:
• Defective erythropoiesis
• Hemolysis
• Morphology of RBC:
• Irregular
• Microcytic
• Hypochromic

3. NUTRITION DEFICIENCY ANEMIA

A. IRON DEFICIENCY ANEMIA

• Iron deficiency anemia is the most common type of anemia.
• It develops due to inadequate availability of iron for hemoglobin synthesis.
• RBCs are:
• Microcytic
• Hypochromic

B. PROTEIN DEFICIENCY ANEMIA

• Protein deficiency decreases hemoglobin synthesis.
• RBCs are:
• Macrocytic
• Hypochromic

C. VITAMIN B₁₂ DEFICIENCY: PERNICIOUS ANEMIA

• Vitamin B₁₂ is a maturation factor for RBC.
• Deficiency of vitamin B₁₂ causes pernicious anemia.
• Pernicious anemia is also called Addison’s anemia.
• It occurs because of:
• Less intake of vitamin B₁₂
• Poor absorption of vitamin B₁₂
• Vitamin B₁₂ is absorbed from the stomach with the help of intrinsic factor of Castle, which is secreted in the gastric mucosa.
• Decrease in the production of intrinsic factor causes poor absorption of vitamin B₁₂.
• RBCs are:
• Macrocytic
• Normochromic/hypochromic

D. FOLIC ACID DEFICIENCY: MEGALOBLASTIC ANEMIA

• Folic acid is necessary for maturation of RBC.
• Deficiency of folic acid leads to defective DNA synthesis, making the nucleus remain immature.
• RBCs are:
• Megaloblastic
• Hypochromic

4. APLASTIC ANEMIA

• Aplastic anemia is due to bone marrow disorder.
• Red bone marrow is reduced and replaced by fatty tissues.
• It occurs in conditions such as:
• Repeated exposure to X-ray or γ-ray radiation
• Tuberculosis
• Viral infections like:
  • Hepatitis
  • HIV infections
• RBCs are:
• Normocytic
• Normochromic

5. ANEMIA DUE TO CHRONIC DISEASES

• Anemia occurs due to some chronic diseases such as:
• Rheumatoid arthritis
• Tuberculosis
• Chronic renal failure
• RBCs are:
• Normocytic
• Normochromic

ETIOLOGICAL CLASSIFICATION — MORPHOLOGY OF RBC

SIGNS AND SYMPTOMS OF ANEMIA

METABOLISM

• Increase in basal metabolic rate

SPLEEN

• Enlargement in some types of anemia

LIVER

• Enlargement in sickle cell anemia
• Jaundice in hemolytic anemia

DIGESTION

• Anorexia
• Nausea
• Vomiting
• Abdominal discomfort
• Constipation
• Black or maroon stool

KIDNEY

• Disturbed renal function
• Albuminuria

REPRODUCTION

Disturbance of menstrual cycle in females:

• Menorrhagia
• Oligomenorrhea
• Amenorrhea

SKIN

• Skin becomes:
• Pale or yellow
• Thin
• Dry
• Non-elastic
• Thinning, loss and early grayness of hair

MUCOUS MEMBRANE

• Paleness
• More prominent in:
• Buccal areas
• Pharyngeal areas

CARDIOVASCULAR SYSTEM

• Tachycardia
• Increased cardiac output
• Dilation of heart
• Cardiac murmur
• Angina
• Heart attack

RESPIRATORY SYSTEM

• Hyperventilation
• Dyspnea
• Shifting of O₂-Hb dissociation curve to right

NERVOUS SYSTEM

• Headache
• Lack of concentration
• Restlessness
• Irritability
• Drowsiness
• Vertigo
• Fainting

MUSCLE

• Weakness
• Easily fatigued
• Lack of energy