2. Factors which influence the size of red cells in
anaemia. โ MCV is < 76 fL; โ MCV is > 100 fL.
Printed from: Davidson's Principles and Practice of Medicine
21E (on 25 March 2013)
ยฉ 2013 Elsevier
7. HEREDITARY SPHEROCYTOSIS
โข Defective or absent spectrin molecule
โข Leads to loss of RBC membrane, leading to
spherocytosis
โข Decreased deformability of cell
โข Increased osmotic fragility
โข Extravascular hemolysis in spleen
โข Autosomal domenent
10. Diagnosis
flow cytometric tests, detecting binding of eosin-5-
maleimide to red cells, are recommended in borderline
cases.
An osmotic fragility test may show increased sensitivity
to lysis in hypotonic saline solutions but is limited by
lack of sensitivity and specificity.
Family screening
Blood film show spherocytes
11. Treatment
Folic acid prophylaxis, 5 mg once weekly, should be
given for life.
Consideration may be given to splenectomy, which
improves but does not normalise red cell survival.
Potential indications include moderate to severe
haemolysis with complications (anaemia and
gallstones), although splenectomy should be delayed
until after 6 years of age in view of the risk of sepsis
18. โข When to suspect G6PD deficiency? โ
Glucose-6-phosphate dehydrogenase
(G6PD) deficiency should be suspected in
any subject with an episode of non-
immune hemolytic anemia, especially if
occurring after drug ingestion, exposure
to fava beans, or associated with an
infection.
19. Care must be taken close to an acute haemolytic
episode because reticulocytes may have higher
enzyme levels and give rise to a false normal
result
Management
aims to stop any precipitant drugs and treat any
underlying infection. Acute transfusion support
may be life-saving.
Administration of folic acid in a dose of 1 mg/day
may prevent worsening of anemia due to folate
depletion in this group of patients.
G6PD level
24. Suspecting hemolysis โ
โข Rapid onset of pallor and anemia
โข Jaundice with increased indirect bilirubin concentration
โข History of pigmented (bilirubin) gallstones
โข Splenomegaly
โข Presence of circulating spherocytic red cells or red cells
with other shape changes
โข Increased serum lactate dehydrogenase (LDH)
โข Reduced (or absent) level of serum haptoglobin
โข A positive direct antiglobulin test (Coombs test)
โข Increased reticulocyte percentage or absolute reticulocyte
number, indicating the bone marrow's response to the
anemia
25. AUTOIMMUNE HEMOLYSIS
Warm Type
โข Usually IgG antibodies
โข Fix complement only to level of C3,if at all
โข Immunoglobulin binding occurs at all temps
โข Fc receptors/C3b recognized by
macrophages;
โข Hemolysis primarily extravascular
โข 70% associated with other illnesses
26. Management
โข prednisolone 1 mg/kg orally. A response is seen in 70-
80% of cases but may take up to 3 weeks;
โข Transfusion support may be required for life-threatening
problems,
โข splenectomy should be considered. with a good response
in 50-60% of cases.
โข immunosuppressive therapy with azathioprine or
cyclophosphamide may be considered.
โข The anti-CD20 (B cell) monoclonal antibody, rituximab,
has shown some success in difficult cases.
27. AUTOIMMUNE HEMOLYSIS
Cold Type
โข Most commonly IgM mediated
โข Antibodies bind best at 30ยบ or lower
โข Fix entire complement cascade
โข Leads to formation of membrane attack complex,
which leads to RBC lysis in vasculature
โข Typically only complement found on cells
โข 90% associated with other illnesses
โข Poorly responsive to steroids, splenectomy;
responsive to plasmapheresis
28. โข Abnormalities on the peripheral blood smear
suggesting extravascular hemolysis include:
spherocytes, microspherocytes, elliptocytes,
"bite" or blister cells, acanthocytes, and
teardrop red cells.
โข Abnormalities that suggest that the
hemolysis is intravascular include the
presence of free hemoglobin in plasma or
urine, a urine sediment positive for iron
(hemosiderinuria), and, in rare cases, the
presence of circulating red cell "ghosts."
29. Cold agglutinin disease
โข underlying low-grade B cell lymphoma.
โข It causes a low-grade intravascular haemolysis with cold,
painful and often blue fingers, toes, ears or nose (so-
called acrocyanosis).
โข MCV may be spuriously raised
โข Treatment is directed at any underlying lymphoma but if
the disease is idiopathic, then patients must keep
extremities warm, especially in winter.
โข Some patients respond to corticosteroid therapy and
blood transfusion may be considered, but the cross-
match sample must be placed in a transport flask at a
temperature of 37 ยฐC and blood administered via a
blood-warmer.
30. โข Other causes of cold agglutination Cold
agglutination can occur in association with
Mycoplasma pneumoniae or with infectious
mononucleosis.
โข Paroxysmal cold haemoglobinuria is a very rare
cause seen in children in association with
congenital syphilis.
โข An IgG antibody is termed the Donath-
Landsteiner antibody and has specificity against
the P antigen on the red cells.