Causes and symptoms of Anemia

                                 ANEMIA

INTRODUCTION

Anemia is defined as a decrease in red blood cell (RBC) mass.

The methods of directly measuring RBC mass are cumbersome & expensive so they are not of much use in clinical practice. Generally, anemia is recognized by the measurement of RBC count, Hematocrit or Hemoglobin (Hb) concentration.

The hematocrit/hemoglobin values vary with the age & sex of the patients & hence appropriate age & sex matching should be performed before arriving at a diagnosis.

CLASSIFICATION

MORPHOLOGICAL

This is usually based on size of RBC & its hemoglobin concentration:

1.     Microcytic – usually hypochromic or normochromic

2.      Normocytic – usually normochromic

3.     Macrocytic –

PATHOPHSIOLOGICAL

1.     Hypoproliferation -  due to bone marrow production defects

a)     Iron deficiaency anemia

b)    Chronic inflammation/Infection

c)     Renal disease

d)    Endocrine & nutritional deficiencies

e)     Marrow damage e.g. infiltration/fibrosis, Aplasia etc.

2.     Ineffective erythropoiesis – due to red cell maturation defects

a.)  Cytoplasmic defects

·        Iron deficiency

·        Thallasemia

·        Sideroblastic anemia

b.)  Nuclear defects

·        Folate deficiency

·        Vitamin B12 deficiency

·        Drug toxicity

·        Refractory anemia

3.     Decreased red cell survival  due to hemolysis/blood loss

·   Hemorrhage

·   Intravascular hemolysis

·   Autoimmune defect

·   Fragmentation hemolysis

·   RBC membrane abnormalities

·   Metablolic disorders

HYPOPROLIFERATIVE ANEMIAS

                 This is the most common type & constitutes roughly three-fourths of all cases of anemias . It basically reflects a partial or total failure of bone marrow to respond to the decreased RBC mass.

It is usually caused by a deficiency of iron or chronic inflammation, marrow damage or inadequate erythropoietin (EPO) stimulation.

The morphology is usually of the normocytic/normochromic type although microcytic hypochromic type may also be seen in some instances esp. with Iron deficiency.

Marrow damage by a drug or leukemia/ infiltrative disorder may also be a cause of reduce marrow proliferation.

A low Reticulocyte production Index with normocytic normochromic picture is typical of this form of anemia.

INEFFECTIVE ERYTHROPOIESIS

 In this case the erythropoiesis is stimulated but the produced erythroblasts have either nuclear or cytoplasmic defects & most of these defective blasts are destroyed before reaching the blood stream rendering the erythropoiesis ineffective.

Blasts with nuclear maturation defects usually show macroctyosis  while those with cytoplasmic defects usually show microcytosis.

So, a low RP Index associated with microcytic/macrocytic picture is suggestive of ineffective erythropoiesis.

Marrow morphology shows erythroid heperplasia ( Myeloid : Erythroid ratio <1:1)

HEMOLYSIS/BLOOD LOSS

This is associated with high RP Index, although an acute blood loss is not associated with increase RP index.

The stimulated production of RBCs is evident in peripheral blood smear by the increase of polychromatophillic macrocytes.

It is usually normocytic though in some cases microcytic picture may be seen due to rise in reticulocytes.

In acute blood loss RP index is not elevated because it takes some time before the EPO stimulation & bone marrow response can be triggered.

Chronic blood loss may often present as iron deficiency anemia.

Hemolytic anemias though rare, present with distinctrive clinical patterns with a common theme of high RP index

Some may present acutely while others may be identified only on incidental blood screening. Others follow an episodic course with relapses & remissions. A careful history of events, family  laboratory investigations may be needed to make a diagnosis.