Haemotology Flashcards
Define anaemia.
Reduced circulating haemoglobin (Hb) per unit volume of blood (i.e.
concentration) when compared with the correct reference range for
age and gender.
Anaemia implies insufficient RBC mass (normal, functional
RBC) to adequately deliver O2
to peripheral tissues.
It is a feature of an underlying disease and not itself a disease.
What are the symptoms associated with anaemia?
Shortness of breath on exertion /exercise intolerance
Weakness
Lethargy
Palpitations
Headaches / dizziness
Older patients: symptoms of cardiac failure, angina pectoris or
confusion.
Pica is specific to deficiencies.
Which factors affect the clinical presentation of anaemia?
Speed of onset, drop the Hb.
The Severity of anaemia
Patient comorbidities.
Patients.
Factors affecting the O2 curve.
What are the signs of anaemia?
General features:
* Pallor of mucous membranes (when Hb < 9 – 10 g/dL).
(skin colour is not a reliable sign)
* Hyperdynamic circulation, with tachycardia and systolic
flow murmur; may find bounding pulse, cardiomegaly
* May see congestive heart failure in the elderly.
Signs linked to particular types of
anaemia
* Jaundice and/or
splenomegaly: haemolytic
anaemia.
* Loss of proprioception and
vibration sense: Vit B12
/folate deficiency.
* Lymphadenopathy,
organomegaly and/or
evidence of chronic blood
loss: underlying malignancy
(haematological/not)
* Leg ulcers: sickle cell
anaemia
* Bone deformities:
thalassaemia major
* Koilonychia (spoon nails):
iron deficiency
Describe a blood smear of Iron Deficiency anaemia.
Microcytic
Hypochromic (large central pallors)
Pencil cells
Increase platelets
Describe a blood smear of Megaloblastic Anaemia.
VIt B12 and Folate deficiencies.
Oval cells (more round in liver disease)
Neutrophil Hypersegmented
Nucleated RBC
Anisocytosis
Pancytopenia
What are the mechanisms to reduce Hb?
- Failure of bone
marrow production
(various reasons)
Low reticulocyte count
May show characteristic blood film findings - Blood loss Clinical evidence of bleeding, later increased
reticulocyte count, eventual Fe deficiency - Increased RBC
destruction
(haemolysis)
Increased reticulocyte count,
Suggestive haemolytic screen* and blood film
findings - RBC Pooling Splenomegaly
What are the congenital causes of anaemia?
Memebranopathies: Mutations affecting the lipid bilayer, integral membrane proteins, or membrane
skeleton affects stability.
Enzymopathies: defect in the Pyruvate kinase will inhibit the Embden-Meyerhoff pathway, with no production of ATP. Decrease in G6PD* (glucose-6-
phosphate dehydrogenase), no production of NADPH, and reduced glutathione, no protection against oxidative stress. Forms Heinz Body.
Haemoglobinopathies: Mutations can cause ineffective Hb, losing its integral to transport O2.
Describe the adjacent metabolic pathway of the Embden-Meyerhoff pathway.
Rapaport-Luebering shunt exists for the synthesis
of 2,3-diphosphoglycerate (2,3-DPG) which is a
important determinant of the oxygen affinity of
haemoglobin.
What is haemolytic anaemia?
Premature destruction of RBC (15-20 days), only if bone marrow cannot compensate.
Intravascular Increase Plasma Hb
Extravascular RBC is destroyed by the spleen, increasing unconjugated Bilirubin
Describe the features of Warm Autoimmune anaemia.
Blue reticulocytes
Spherocytes
+/- Nucleated RBC
+ polychromasia and Howell Jolly Bodies: a sign of rapid erythropoiesis
Polyclonal reactive B cell
+DAT
Describe the features of Cold Autoimmune Anaemia.
CHAD, Jaundice, mild anaemia, acroyanosis (lemon Yellow)
erroneously High MCV: agglutinations
monoclonal Ab
+DAT
What is the pathogenesis of drug-induced anaemia?
Drug-specific Ab attaches to RBC
Immune complex deposition
True autoAb induced
membrane modification
+DAT
Explain Paroxysmal Nocturnal Haemoglobinuria.
Mutation in the gene that codes for GPI. ineffective anchoring of the Surface protein. RBC are more sensitive to complement-induced lysing
How does haemolysis lead to splenomegaly?
Increased activity of the macrophage-reticuloendothelial cells in the spleen that are activated in phagocytosing the damaged red cells
