Haemolytic Anaemia Flashcards
What is haemolytic anaemia?
It is anemia due to shortened RBC lifespan
What is the lifespan of cells which are haemolytic?
Less than 120 days (less than 15 days survival)
What does the bone marrow usually do in response to haemolytic anaemia? What is the stimulus for this?
It increases erythropoiesis, driven by EPO stimulus
In haemolysis red cells are destroyed by…
Macrophages
Globin chains are degraded to which of the following?
(a) carbohydrates
(b) bilirubin
(c) haptoglobin
(d) amino acids
(e) folate
(d) amino acids
Outline what happens to haem when it is degraded during haemolytic anaemia
Haem binds to haptoglobin, then is degraded to protoporphyrin and then is metabolised to bilirubin which is excreted through faeces or urine.
Outline what happens to iron when degraded by haemolytic anaemia
Iron binds to transferrin and then is stored as ferritin in macrophages. Hence, it is released and recycled.
Red cell destruction is extravascular when it is in…
Macrophages
Red cell destruction is intravascular when it is within…
Blood vessels
Outline the markers for haemolytic anaemia:
1) Increased bilirubin due to extravascular haem breakdown
2) Increased LDH
3) Reduced haptoglobins due to Hb-haptoglobin complexes
4) Spherocytes
5) Fragmented red cells (schistocytes)
6) Polychromasia
Which of the following would count as good evidence that the patient has haemolytic anaemia:
(a) elliptocytes
(b) plasma cells in the blood
(c) macrocytes
(d) nucleated blood cells in blood
(e) microcytes
Nucleated blood cells in the blood - which should be in the bone marrow. Increased RBC production and compensation by the bone marrow leads to some early progenitor cells like reticulocytes and nucleated red blood cells in the blood. They come out before they are ready, and polychromasia is another evidence for increased RBC production.
The plasma has a red tinge due to the destruction of the RBCs. True or False:
True
Is Lactose Dehydrogenase a good marker for hemolysis?
Yes, because it is present in the RBCs and is released into the plasma due to haemolysis
Distinguish between the laboratory features of extravascular and intravascular haemolytic anaemia:
Extravascular:
Polychromasia and altered RBC shape
LDH elevated
Bilirubin elevated
Intravascular: Fragmented red cells Low haptoglobin Hb in plasma Haemosiderin in urine
Explain the key clinical features of haemolytic anaemia?
Jaundice (due to bilirubin in the plasma)
Gallstones (due to excess bilirubin)
Splenomegaly
Expanded bone marrow (chronic erythroid hyperplasia)
Megaloblastic anaemia (due to folate deficiency as the folate stores run out when there is an increased drive to make new cells)
What causes haemolytic anaemia?
Hereditary causes like:
Membrane defect: hereditary spherocytosis
Enzyme defect: G6PD and PK deficiency
Globin chain defect: haemoglobinopathies
There are also acquired causes
Explain why RBC membranes must be deformable?
RBC membranes must be deformable and stable. It is the abnormal RBC membrane deformability, which leads to a reduced RBC lifespan, and hereditary disorders.
Phospholipid & membrane proteins determine this disorder. Mutations in the genes of membrane skeletal proteins,.
Hereditary spherocytosis is the least common inherited haemolytic anaemia. True or False?
False, it is the most common
How is hereditary spherocytosis inherited? Which protein is mutated?
Autosomal dominant
Defect in any/all structural RBC membrane proteins
(Spectrin, ankyrin, band 3)
Explain Hereditary Spherocytosis:
RBC is less deformable, and it loses the membrane when passing through the spleen microcirculation
RBCs become spherical, rigid, and then are destroyed, with no central palor
(think sphere = membrane shape)
What is the result of DAT (direct antibody test) / Direct Coombs test in hereditary spherocytosis?
(a) positive because antibodies are not coating the RBC
(b) negative because antibodies are coating the RBC
(c) negative because antibodies are not coating the RBC
(d) positive because antibodies are coating the RBC
C - negative because antibodies are most likely not attached to your RBCs
Outline treatment options for hereditary spherocytosis
Splenectomy
Folic acid
How is herditary elliptocytosis inherited?
(a) Autosomal dominant
(b) Autosomal recessive
(c) X-linked recessive
(d) X-linked dominant
a - autosomal dominant
Is hereditary elliptocytosis milder than hereditary spherocytosis?
Yes, milder than HS as only 10% have haemolysis