Red Blood Cell Diseases Flashcards
What are the 8 parts with units of a full blood count?
- WBC - white blood cell count (x10^9/L)
- RBC - red blood cell count (x10^12/L)
- Hb - haemoglobin concentration (g/L)
- Hct - haematocrit = % of blood that is rbcs (%)
- MCV - mean cell volume (fL —> 10^-15)
- MCH - mean cell haemoglobin (pg —> 10^-12)
- MCHC - mean cell haemoglobin concentration (g/L)
- Platelet count (x10^9/L)
How do you calculate MCV?
MCV = Hct/RBC x 1000
- think about units 10^-9L = 10^-12L x 1000
How do you calculate MCH?
MCH = Hb/RBC
∵ Hb per RBC = total Hb / no. RBCs
g/L = g/L / no.
How do you calculate MCHC?
MCHC = Hb/Hct
∵ Hb conc per RBC = total Hb / proportion of RBCs
g/L = g/L / % no.
How are blood cell counts performed now?
Automated instruments
- cell flows between light source and sensor/through electric field —> electronic impulses
What are the 2 indicators of anaemia on a FBC?
- Low Hb
- Low MCV
Which 4 features of erythrocytes distinguish the type of anaemia on a blood film?
- Size (microcytic, normocytic, macrocytic)
- Shape
- Colour (pale, polychromasia)
- Poikilocytes - abnormal shapes
How is iron deficiency anaemia indicated on a FBC? (4)
- Low Hb
- Low MCV
- Low MCH
- Low MCHC
(5. High transferrin)
How is iron deficiency anaemia indicated on a blood film?
Microcytic erythrocytes (small and pale)
How is thalassaemia trait identified on a blood film?
Microcytic erythrocytes (small and pale)
What is anaemia?
Low Hb
What is thalassaemia?
Abnormal Hb production leading to anaemia
Which 2 lab techniques can be performed to see the presence of different Hbs in blood?
Hb electrophoresis
HPLC (high performance liquid chromatography)
What is the electrophoresis pattern of Hb?
HbA
HbF
(HbS)
HbA2
How is anaemia of chronic disease indicated on a FBC with transferrin and protein measures?
- Low Hb
- Low MCV
- Low transferrin
- High C-reactive protein
How is thalassaemia trait indicated on a FBC?
- Low Hb
- Low MCV
- Low MCH
What are the 4 common causes of microcytic anaemia and why?
- Iron deficiency anaemia
- Anaemia of chronic disease
- α-Thalassaemia
- β-Thalassaemia
How is megaloblastic anaemia indicated on a blood film?
Macrocytic erythrocytes
What are the 4 common causes of macrocytic anaemia?
- Megaloblastic anaemia (B12/folic acid deficiency)
- Drugs interfering with DNA synthesis
- Liver disease/ethanol toxicity
- Haemolytic anaemia
What are the 3 causes of haemolytic anaemia
- Hereditary Spherocytosis
- SCD
- G6PD deficiency
What is microcytic anaemia?
- Low Hb
- Smaller erythrocytes
What is macrocytic anaemia?
- Low Hb
- Larger erythrocytes
What is haemolytic anaemia?
- Low Hb
- Shortened erythrocyte lifespan
How is haemolytic anaemia indicated on a blood film? (3)
- Poikilocytes
- Polychromasia
- Reticulocytes high
What are the 3 causes of normocytic anaemia?
- Blood loss
(haemorrhage, trauma) - Failure to produce erythrocytes
(bone marrow issues, anaemia of chronic disease) - Erythrocytes pooling in spleen
(hypersplenism-liver cirrhosis, splenic sequestration-SCD in infants)
What are poikilocytes?
Abnormally shaped red blood cells
- not biconcave disc
What are the 6 types of poikilocytes?
- Target cells —> dark centre ∵ accumulated Hb
- Sickle cells
- Red cell fragments (Schizocytes)
- Spherocytes
- Elliptocytes
- Irregularly contracted cells eg. blister cells
How is sickle cell anaemia indicated on a FBC?
- High RBC
- Low MCV
- Low MCH
What are 6 important types of anaemia and their causes?
- Iron deficiency anaemia
- Megaloblastic anaemia —> B12/folate deficiency
- Anaemia of chronic disease
- Sickle cell anaemia —> autosomal recessive
- Thalassaemia —> autosomal dominant
- Haemolytic anaemia
How is SCD indicated on a blood film? (5)
- Sickle cells
- Boat cells
- Target cells
- Howell Jolly bodies - erythrocyte nuclei (should be removed by spleen)
- Platelets high
When and why do erythrocytes become sickled in SCD?
Hypoxia
- Polymerisation forming insoluble HbS
What are the 4 causes of target cells in a blood film?
- Obstructive jaundice
- Liver disease
- Haemoglobinopathies
- Hyposplenism
How is SCD indicated via Hb electrophoresis?
- No HbA
- High HbF (only α + γ —> no mutated β)
- High HbS
What mutation causes SCD?
- Glutamic acid —> Valine
- Position 6
- β-globin gene
What is the difference between SCT and SCD?
- Trait —> heterozygous (HbA + HbS)
- Disease —> homozygous (HbS + HbS) —> symptoms
What 3 effects do sickle cells have regarding the circulatory system?
- Haemolysis
- Shortened erythrocyte lifespan (20 days)
- Vaso-occlusion
What are the 6 symptoms of SCD?
- Anaemia
- Jaundice (bilirubin)
- Gallstones
- Crises
- Dactylitis
- Splenomegaly
What are the 6 sites of vaso-occlusion in SCD?
- Bone
- Kidney
- Cerebral
- Retina
- Lung
- Spleen
How is the difference between Hb affinity of HbA and HbS?
HbS lower affinity for Hb
How does SCD affect the spleen and what are the consequences of this?
- Vaco-occlusion —> hyposplenism
- Functional hyposplenism by age 5 - spleen stops working
- Inc susceptibility to encapsulated bacteria —> give immunisations and prophylactic antibiotics
How is polycythaemia indicated on a FBC? (3)
- High Hb
- High Hct
- High RBC
What might high Hb and an abdominal mass indicate?
Kidney carcinoma
What might high Hb, breathlessness and cyanosis indicate?
Hypoxia —> polycythaemia
What might high Hb and splenomegaly indicate?
Polycythaemia vera
What might high Hb in a healthy athlete indicate?
Blood doping/erythropoietin use —> polycythaemia
