Anaemia - MedED Flashcards
Differentiate between IDA and ACD
IDA - everything low except transferrin and TIBC
ACD - everything low except ferritin, mainly normocytic
Causes of IDA
Malabsorption:
Malnutrition
Coeliac disease
IBD
Increased use:
Pregnancy
Growth
Increased loss: menorrhagia GI malignancy Peptic ulcer IBD
Key blood film features of IDA
Pencil cells
Hypochromia
Aniso-poikilocytosis
Four types of alpha thalassemia and their complications
Alpha +
Alpha *
Hb H (lack 3 alpha genes, requires blood transfusion for life)
Hb barts (death in utero)
Three types of beta thalassemia and their complications
Beta minor - mild anaemia but disportionately low MCV) Beta intermedia Beta major (severe anaemia presenting in first few months of life, requiring transfusion for life)
Epidemiology of Thalassemia
Cyprus
Investigations for thalassemia - also what is the gold standard?
Microcytic anaemia + film
Normal iron studies
Gel electrophoresis (gold standard)
Explain the haemoglobin shift from fetus to infancy and why alpha and beta thalassemia present at different time stages
In utero - gamma globin + alpha
Hence alpha presents before birth
You switch to beta globin around 3-6m so beta thalassemia presents in infancy
Explain sickle cell disease and its complications
Point mutation in beta globin chain on chromosome 11.
The beta subunit has the amino acid valine at position 6 instead of the glutamic acid that is normally present.
Autosomal recessive.
Sickling makes the rbc more prone to intravascular haemolysis, therefore you get haemolytic jaundice.
What might precipitate sickling?
Hypoxia
Dehydration
Acidosis
Infection esp capsuled infections
Why are sickle cells/thalassemia though to be evolutionary advantages?
Both sickle cell disease and thalassemia prevent malaria falciparum from actually hijacking the actin from rbc, thus preventing it from adhering to other RBCs and the spread of the disease.
Blood film findings for sickle cell disease
Howell-Jolly bodies (spots within a cell) - these are nuclear remnants which are usually filtered out by the spleen. They signify poor spleen function due to splenic infarcts from vasoocclusion.
Life span of a sickled blood cell
10-20 days
Complications of sickle cell disease
Acute painful crisis
Stroke (vasoocclusion)
Sequestration crisis in spleen, as all faulty rbc get stuck in spleen causing splenomegaly
Chronic cholecystitis
What do howell-jolly bodies mean?
Spleen no longer working
You might see hyposplenism
How do you manage an acute painful crisis?
Sickle Acute Painful Crisis
Saturate with oxygen
Antibiotics if needed
Pain relief
Cannula for IV fluids
Diagnosis of sickle cell anaemia
Hb electrophoresis and blood film
Symptoms of sickle cell anaemia
Dactylitis Priapism Haemolytic anaemia causing jaundice Acute chest syndrome? Aplastic crisis due to parvovirus B19
Mx of sickle cell anaemia
Conservative: trigger avoidance + vaccination
Medical: Hydroxyurea + prophylatic abx
Surgical - bone marrow transplant
What is seen on the blood film of someone with B12/folate deficiency?
Macrocytic, MEGALOBLASTIC anaemia (hypersegmented neutrophils)
Causes of vit B12 and folate deficiencies
Causes of both:
Alcohol
IBD/coeliac
Folate:
Pregnancy
Anitfolate drugs
B12:
Pernicious anaemia
Dietary malabsorption
How long do B12 stores last?
3-4 years
How long do folate stores last?
6 months
What neurological complication is associated with B12 deficiency?
Subacute combined degeneration of the cord
Glove and stocking parasthesia
Hyporeflexia
Romberg’s positive
Antibodies in pernicious anaemia
Anti intrinsic factor
Anti parietal cells
Types of haemolytic anaemias
Disorders of membrane - hereditary spherocytosis
Disorders of enzyme - G6PD
Disorders of haeoglobin thalassemia / sickle cell
Intravascular
Extravascular (in spleen)
Signs of haemolytic anaemia
Low Hb Low haptoglobin (as it is exhausted?) Unconjugated bilirubin is raised LDH raised as leaks out form cells
Glucose 6 phosphate deficiency - pathophysiology
Reduces glutathione stores which are really important for dealing with oxidative stress.
What foods should people with G6PD avoid?
Broad beans / fava beans
Napthalene moth balls
Antimalaraials (quinines)
Hereditary pattern of G6PD
oXidative stress; X linked
What is seen on the blood film of someone with G6PD?
Heinz bodies (active haemolysis, intracellular inclusions of denatured haemoglobin)
Bite cells (where the spleen has taken a ‘bite’ out of the cell)
A haemolytic disease affecting white people
Hereditary spherocytosis
Hereditary spherocytosis key features, cause
Spherocytes
Beta spectrin/ankyrin deficiency causing weak cytoskeleton and globular RBC
Test for HS
Osmotic fragility test - give the patient hypotonic saline; it stresses out the rbc and causes them to break down
New test for HS
Osmotic fragility test - give the patient hypotonic saline; it stresses out the rbc and causes them to break down
New test: Eosin-5-maleimide binding blood test
What test comes back negative for HS?
Coombs test (testing for antibodies against RBC)
What is a major complication of sickle cell anaemia and hereditary spherocytosis and why?
APLASTIC CRISIS
Parvovirus B19 infections bone marrow, so body relies on circulating RBC to function. However RBC in HS lasts around 30 days, and in sickle cell, around 10 days, so you FAIL TO PRODUCE RED BLOOD CELLS.
