Anemia: Classification, Signs and Symptoms, Treatment

Anemia is defined as a decrease in the red blood cell count, hemoglobin and/or hematocrit values as compared to the normal reference range for age and sex.

Anemias are disorders that involve a reduction in the number of erythrocytes and include both inherited and acquired disorders.

As a general rule, anaemias are the result of either

• Altered production of red cells,
• A loss of blood volume,
• Increased erythrocyte destruction or
• A combination of these.

Classification of Anaemia

The most common classification system used to define anemias centers on the physical characteristics of the erythrocytes (size and hemoglobin content)

If there is a change in cell size, the suffix -CYTIC is used (e.g. normocytic, macrocytic, microcytic),

If there is an alteration in hemoglobin content, the suffix-CHROMIC is used (e.g. normochromic, hyperchromic, hypochromic).

Macrocytic disorders include : pernicious and folate-deficiency anaemias.

Microcytic disorders are iron-deficiency aneamias and thalassaemias. 
Aplastic, hemolytic and sickle cell anemias are normocytic disorders.
All anemias, irrespective of the cause, result in reduced oxygen-carrying capacity.

True vs Pseudo anemia

‘True anaemia is when there is a decreased red blood cell mass and normal plasma volume. 
Pseudo or dilutional anaemia….normal red blood mass and increased plasma volume.

An increase in plasma volume may cause a dilutional or pseudo anemia (with low Hgb & HCT values) even though the RBC mass is normal ....can occur during pregnancy or caused by volume overload (IVs), congestive heart failure

Normal reference ranges

Normal RBC is between 4.5-5.9 X10^6  in male and  4.1-5.1 x10^6 in  female/l
[Hemoglobin] 14.0g/dl-17.5g/dl male and 12.3g/dl-15.3g/dl in female
Hematocrit is 43% – 50% male and  36%- 45% in female

1.Classification of anaemia

I. Etiologic Classification

A.Impaired RBC production
B.Excessive destruction 
C.Blood loss

II. Morphologic Classification

A.Macrocytic anaemia 
B.Microcytic hypochromic anemia 
C.Normochromic normocytic anemia

An Impaired RBC Production 
1. Abnormal bone marrow 
Aplastic anemia 
Myelophthisis: Myelofibrosis, Leukemia

2. Essential factors deficiency 
Deficiency anemia: Fe, Vit. B12, Folic acid
Anemia in renal disease: Erythropoietin

3. Stimulation factor deficiency 
Anaemia in chronic disease 
Aneamia in hypopituitarism 
Anaemia in hypothyroidism

B Excessive Destruction of RBC

Hemolytic anemia 
Intracorpuscular defect;-
Membrane defect: Hereditary spherocytosis Hereditary ovalocytosis 
Enzyme defect: G-6PD deficiency
Hemoglobin defect: Thalassemia, Hemoglobinopathies

Extracorpuscular defect
Mechanical defect: March hemolytic anemia MAHA (Microangiopathic HA) 
Chemical/Physical factors
Infection: Clostridium tetani 
Antibodies: HTR, SLE 
Hypersplenism

C Blood Loss

Acute blood loss: Accident, GI bleeding 
Chronic blood loss: Hypermenorrhea, Parasitic infestation

II. Morphologic classification

Macrocytic Anaemia MCV > 94 MCHC > 31 caused by
Megaloblastic dyspoiesis 
Vit. B12 deficiency: Pernicious anemia 
Folic acid deficiency: Nutritional megaloblastic anemia
Inborn errors of metabolism: Orotic aciduria, 
Abnormal DNA synthesis: Chemotherapy, Anticonvulsant, Oral contraceptives

Microcytic Hypochromic Anaemia MCV < 80 MCHC < 27

Fe deficiency anaemia: Chronic blood loss, Inadequate diet, Malabsorption, Increased demand
Abnormal globin synthesis: Thalassemia with or without Hemoglobinopathies 
Abnormal porphyrin and heme synthesis: Pyridoxine responsive anemia, 
Other abnormal Fe metabolism:

Normocytic-Normochromic Anemia MCV 82 - 92 MCHC > 30

Blood loss, Increased plasma volume: Pregnancy, Overhydration 
Hemolytic anemia, Hypoplastic marrow: Aplastic anaemia, RBC aplasia 
Infiltrate bone marrow: Leukemia, Multiple myelomas, Myelofibrosis,

Abnormal endocrine: Hypothyroidism, Adrenal insufficiency, Kidney disease/Liver disease/Cirrhosis

Clinical manifestations of anemia

The symptoms of anemia will be more severe if the onset is rapid or if there is coexisting cardiorespiratory disease.

Many clinical features are non-specific but together they should raise suspicion of anemia.
Symptoms include:

● Tiredness.
● Lightheadedness.
● Breathlessness.
● Worsening of coexisting disease, e.g. angina.

Signs include:

● Mucous membrane pallor
● Tachypnoea.
● Raised JVP.
● Flow murmurs.
● Ankle edema.
● Postural hypotension.
●Tachycardia.

The clinical assessment and investigation of anaemia should gauge its severity and define the underlying cause

Treatment

No treatment of the anaemia is necessary and the primary management is to address the condition causing the anemia

Oral Iron and parenteral iron
Ferrous sulfate, 325 mg once daily on an empty stomach, is a standard approach for replenishing iron stores

When the anemia is severe or is adversely affecting the quality of life or functional status, then treatment involves either red blood cell transfusions or parenteral recombinant erythropoietin.

Folic acid supplementation (1 mg/day orally)

IM or subcutaneous injections of 100 mcg of vitamin B12

Folic acid deficiency is treated with daily oral folic acid (1 mg)
Avoid known oxidant medications