Haemolytic Anaemia - Introduction

What is Haemolytic Anaemia?

Basic definition would be reduction in Hb level of an individual below the appropriate value for the age and sex due to increased rate of red cell destruction.It can lead to a

1. shortened life span of red cells 120 days 

2. elevated Erythropoietin levels

3. bone marrow hyperplasia

4. accumulation of hemoglobin degradation products 

Heamolysis happens in 2 main mechanisms.

1. Extravascular hemolysis – in the bone marrow, liver and spleen. Normally occur in physiological conditions. If increased the rate will be abnormal.

2. Intravascular hemolysis – occurs within the circulation mostly in abnormal conditions.

In some haemolytic anemic situations, both extravascular and intravascular hemolysis may happen.

Clinical features of Haemolytic Anaemia

• Fatigue
• Sleepiness
• Pallor of mucous membranes
• Mild fluctuating jaundice
• Spleenomegaly
• Pigment gall stones
• Dark urine

Laboratory findings

1. Features of increased red cell breakdown

1. High serum bilirubin

2. High urine urobilinogen

3. Absence of serum Haptoglobin

2. Features of increased red cell production

1. Reticulocytosis

2. Bone marrow erythroid hyperplasia (normal marrow myeloid: erythroid ratio is 2:1 to 12:1. It is reduced to 1:1/ reversed)

3. Features of damaged red cells

1. Morphology – spherocytes, elliptocytes, fragments

2. High osmotic fragility. Autohaemolysis

3. High level of specific enzymes/ proteins - LDH

Laboratory Evaluation

	Extravascular	Intravascular
Hematologic
Blood film	Polychromatophilia	Polychromatophilia
Reticulocyte count	High	High
Bone marrow examination	Erythroid hyperplasia	Erythroid hyperplasia
Plasma/ serum
Bilirubin	High level of unconjugated bilirubin	High level of unconjugated bilirubin
Haptoglobin	Low/ absent	Low/ absent
Plasma Hb	Nil/ slightly high	High
Methaemalbumin	Negative	Positive
LDH(Lactate dehydrogenase)	High	High
Urine
Haemosiderin	Absent	Present
Hb	Absent	Present
Splenomegaly	Present	Absent

Classification of Haemolytic Anaemia

Hereditary hemolytic anemia	Acquired hemolytic anemia
RBC membrane defects	Immune
Hereditary spherocytosis	Alloimmune
Hereditary elliptocytosis	Haemolytic transfusion reactions
Metabolic enzyme defects	Haemolytic diseases of new born
G6PD deficiency	Allografts- stem cell transplantation
Pyruvate kinase deficiency	Autoimmune
Haemoglobin defects	Warm antibody haemolytic anemia
Genetic abnormalities (Hb S, Hb C etc.)	Cold antibody haemolytic anemia
	Non immune
	Mechanical trauma
	Traumatic cardiac haemolytic anemia March haemoglobinuria Red cell fragmentation syndrome Thermal injuries; burns
	Infection
	Falciparum malaria, Clostridium perfringens septicemia
	Chemicals/drugs
	Oxidant denaturation of Hb      e.g; Dapsone, Arsenic gas, Sulphasalazine, copper, nitrates, Nitrobenzene toxins – snake bites drug induced immune haemolytic anemia – Penicillin, Quinine
	Paroxysmal nocturnal haemoglobinuria

Reference- Dacie and Lewis Practical Haematology 

-Madya Pathirage -