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Haemolytic anaemias
Dr. Suhair Abbas Ahmed
Haemolytic anaemias (HAs)
• HAs are defined as those anaemias
which result from an increase in the
rate of red cell destruction.
• any condition which leads to a
reduction in the mean lifespan of the
red cell is a haemolytic disorder.
• Because of erythropoietic hyperplasia and
anatomical extension of bone marrow, red
cell destruction may be increased several fold
before the patient become anaemic --compensated haemolytic anaemia.
• The normal adult marrow, after full
expansion, is able to produce red cells at 6-8
times the normal rate.
• Therefore HA may not be seen until the red
cell lifespan is less than 30 days.
Classification of HA
• The HA can be classified in several different
ways:
1- Site of haemolysis:
• Extravascular haemolytic disorders macrophages of the RES
• Intravascular haemolytic disorders- within the
circulatory system
• In many of the cases there is a combination
of both extra and intravascular haemolysis.
Extravascular haemolysis
• Red cell destruction
usually occurs in the
cell of the RES.
Intravascular haemolysis
• Destruction of red
cells occur inside the
blood vessels.
Classification of HA
2- Site of defect:
• Intrinsic defect (intracorpuscular)structural or functional defect within the
red cell.
• Extrinsic defect (extracorpuscular)- an
abnormality in the red cell environment.
Classification of HA
3- Inherited or acquired:
• Inherited HA are usually caused by intrinsic
defect.
• While acquired HA are caused by an extrinsic
defect.
• However there are some exceptions:
Paroxysmal nocturnal haemoglobinuria (PNH)
which is an acquired intrinsic defect, and
severe hereditaryG6PD enz deficiency which
requires the presence of an extrinsic trigger
such as the antimalarial drug for the intrinsic
defect to manifest.
Inherited & acquired HA
Hereditary HA
• Membrane defects e.g
hereditary spherocytosis
• Metabolic defect e.g
G6PD deficiency.
• Haemoglobin defects
e.g sickle cell disease.
Acquired HA
– Immune
-Autoimmune eg AIHA
-Alloimmune e.g HDN,
HTR
– Red cell
fragmentation
syndromes
– March
haemoglobinaemia
– Infections
– Chemical and physical
agents.
– PNH
Approach to the diagnosis of
haemolytic anaemias.
Patient’s history
• Good history is essential to provide guidance
for the diagnosis of haemolytic disorders. The
following points should not be neglected:
• Family history--- hereditary conditions, mode
of inheritance.
• Ethnic origin--- G6PD deficiency is most
common in Mediterranean and Chinese
populations.
• Past history--- NNJ may be indicative of
congenital conditions as HS or G6PD
deficiency.
• Triggering events--- history of drugs,
infections
Clinical features
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Pallor of the mucous membranes
Mild fluctuating jaundice
Splenomegaly
Dark urine
Pigment gall stones.
Ulcers around the ankle
Aplastic crisis may complicate viral infections.
Growth retardation
Hypertrophic skeletal changes
• Leg ulcers in
patients with severe
congenital
haemolytic
disorders. e.g sickle
cell anaemia
• Skeletal changes in
patients with b
thalassaemia.
Laboratory findings
• The lab. Findings are divided into 3
groups:
1- Features of increased red cell
breakdown.
2- Features of increased red cell
production.
3- Damaged red cells.
Laboratory findings
1-Features of increased red cell
breakdown:
• Raised S.bilirubin, unconjugated and
bound to albumin.
• Increased urine urobilinogen.
• Increased faecal stercobilinogen.
• Absent S.haptoglobins (saturated with
Hb and removed by the RE cells).
Laboratory findings
2-Features of increased red cell
production:
• Reticulocytosis
• Bone marrow erythroid hyperplasia.
Laboratory findings
• 3-Damaged red cells:
• Morphology– microspherocytes,
elliptocytes, fragments, etc.,….
• Special tests: Osmotic fragility,
autohaemolysis…..
• Red cell survival is shortened; this is
best shown by 51Cr labelling with study
of the sites of destruction.
• Reticulocytosis is a
feature of increased
red cell production.
• New methylene blue
is used to stain the
reticulocytes
• Fragmented cells,
and bitten cells are
sings of damaged
cells occurring in
haemolysis
Intravascular haemolysis
Intravascular haemolysis
• Free Hb will be released from damaged red
cells.
• This free Hb will rapidly saturates plasma
haptoglobins. The complex will be removed
by the liver.
• The excess free Hb is filtered by the
glomerulus, and free Hb will enter the urine,
as iron is released, the renal tubules become
loaded with haemosiderin.
• Methaemalbumin and haemopexin are also
found in the process of IV haemolysis.
• The process of
intravascular
haemolysis
• Liberation of free Hb
• Filtered through the
kidney
• Appear in urine as
haemoglobinuria
Lab features of intravascular
haemolysis
• Haemoglobinaemia & haemoglobinuria.
• Haemosiderinuria (iron storage protein
in the spun deposit of urine).
• Methaemalbumin (detected by
Schumm’s test).
Haemoglobinuria
• Notice the dark
colour of urine
compared to the
normal colour in the
other container.
• This is a sign of
intravascular
haemolysis.
Conclusion
• Good history taking is essential in guiding the
physician towards the correct diagnosis.
• Clinical findings seldom are sufficient to
enable a definitive diagnosis of a particular
haemolytic condition to be made.
• Lab investigations play a central role in the
accurate diagnosis of haemolysis.