Haematology Flashcards
Where are RBC, platelets and most of the WBC produced?
Bone marrow
Who has more extensive bone marrow ?
Infants
In adulthood bone marrow is limited to predominantly where?
Pelvis Sternim Skull Ribs Vertebrae
What controls haematopoeisis?
Hormones and cytokines
How do hormones and cytokines control haemopoiesis?
Alter gene expression, altering how a stem cell divides
For a haemopoetic stem cell to become an erythrocytes what must it first differentiate into
Myeloid progenitor
What system removes faulty cells (rbc)
Reticuloendothelial system (RES)
What is the main organ that disposed of faulty blood cells
Spleen
What does the mean cell volume help us differentiate between?
Microcytic, normocytic and macrocytic disorders.
How long is a red cells life?
120 days
In what state do rbc carry haemoglobin (the iron)
Ferrous state
Why do red cells need to generate atp
To maintain membrane and osmotic equilibrium
What shape are RBC
Biconcave
Why are RBC biconcave
It allows them to passage through microcirculation
A change in rbc shape often results in what?
Lysis
What are some RBC shape changes ?
Spherocytes, speculated, sickle
Haemaglobin is what structure?
Tetramer of 2 pairs of globin chains
What states can haemaglobin be in?
T and R
Where are the globin genes located?
Chromosome 11 and 16
What is important about globin gene expresion and age?
Different expression at different ages
When do we switch rom foetal to adult haemaglobin?
3-6months
What is the purpose of globin in relation to haem?
Protect haem from oxidation keeping it ferous.
Promotes variation in affinity
When RBC are broken down what is the fate of globin, haem and the iron?
Globin broken down into aminos and reformed
Iron retained from haem
Wate haem into billivurdin
What colour is billivurdin?
Green
What is haem broken down into (fully)
First billivurdin
Then billirubin
Then stercobillin in faeces or urobillnogen in urine
What organ controls erythropoeises?
Kidney
What does the kidney do if reduced pO2 is detected in the interstitial peritubular of the kidney?
EPO is produced
What does EPO stimulate?
Maturation and release of RBC from marrow
How is the release of EPO regulated?
A raise in pO2 reduced EPO production
Why is kidney damage associated with anaemia?
Reduced EPO production
What 2 metabolic pathways do RBC use to generate ATP?
Glycolysis (glucose to Lactate)
Pentode phosphate pathway
What are some key roles of iron?
Transport and store oxygen
Integral part of many enzymes
Collagen formation
Neurotransmitter production
What mechanism do we have to excrete iron?
We dont!
How do we excrete iron from the body?
Bleeding
Loss of skin and hair
Can’t actively excrete
What is the consequence of low or high iron?
Anaemia if low
Dangerous deposition if high
Iron in the body is in what 2 forms?
Available or stored
What examples of available iron in the body are there?
Haemoglobin
Myoglobin
Tissue iron (enzyme)
Transported iron (serum iron)
What are some examples of stored iron in the body
Ferritin
Haemosiderin
Macrophage iron
When does the iron status (required) increase in life?
Pregnancy
Children
Where does 80% of active iron come from?
Recycling
Not from gut absorption
What is an iron macrophage?
One that eats an old senescent red blood ell mostly splenic macrophages and kupfer cells of the liver
Where is 85% of stored iron located?
As ferritin in hepatocytes
How much iron enters and leaves the body in a day?
1-2g
What is the best source of iron intake?
Haem sources
How much iron do we need in our diet in a day?
10-15mg
Why is haem intake of iron better than non haem?
Haem enters as fe2+ ferrous
Non haem enters as Fe3+ feriric
What has to happen to ferric iron before it can enter the body?
It has to be reduced
What does fe2+ bind to to enter cells (where)
Divalent metal transporter 1 in apical cells of duodenum and upper jejunum
How does iron get transported out of the apical cells of duodenum
Ferroportin
What is required for iron to enter a cell, such as a RBC?
Iron transferrin complex
Binds to transferrin receptor
What is essential in enhancing absorbtion of non haem iron?
What suggestion does this lead to when talking iron supplements
Ascorbic acid
Take with OJ not with cuppa (antacid)
How do we regulate how much iron we absorb?
Hepcidin
What does hepcidin do?
Binds to ferroportin and stops iron absorbtion
Where is hepcidin transported from?
LIver and kidneys
What leads to Hepcidin synthesis ? What leads to decreased hepcidin?
Iron overload increases synthesis
High EPO activity decreases it
What’s the most common nutritional disorder
Iron defficency
Is iron defficency a diagnosis?
No its a symptom
What are the 3 root causes of iron defficeny
Poor intake Physiological loss (period) Pathological loss
What are some symptoms of iron defficent anaemia
Tiredness, reduced ex tolerance. Pale (reduced o2 carrying)
What are some signs of iron defficent anaemia
Tachycardia, increased RR, pallor
In iron defficent anaemia what is the HB content? What do the cells look like?
Hypochromic, low HB , look pale
What size are rbc in iron defficent anaemia?
Microcytic (small mcv)
What changes other than microcytic and hypochromic are there in iron defficent anaemia?
Change in shape
Low serum ferritin
Low reticulocyte haemoglobin content
What do reduced ferritin level indicate?
Iron defficent anaemia?
Can you rule out iron defficent anaemia with normal ferritin? Why
No
Ferritin raised with inflammation, liver disease, alcoholism
What marker is used to test for functional iron defficent anaemia? When can this not be used?
CHR
Thalassaemia
How would you treat iron defficent anaemia?
Diet, oral iron, IM injection, IV iron.
Transfusion if cardiac comprimise likely
Why is excess iron dangerous?
Causes damage to lipid membranes and proteins
Deposited in tissues
What ca reduced iron produce that are dangerous?
Reactive hydroxyl and lipid radicals
What disease is associated with excess iron ?
Haemochromatosis
What does haemochromatosis damage?
End organs
What secondary diseases can haemochromatosis lead to
Liver cirrhosis
Diabetes
Cardiomyopathy
Arthropathy
Haemochromatosis is due to a mutation in what?
HFE gene
What’s anaemia?
Inability to deliver enough oxygen to tissue due to decreased RBC or decreased haem
The spleen is where?
Left upper quadrant
The process of making red blood cells is known as what?
Eryhtropoesis
If erythropoeisis is reduced or not effective what is it known as?
Dyserythropoiesis
Why does chemo induce anemia?
The bone marrow can become empty meaning it cant respond to EPO
What does a marrow infiltrate do to cause anemia
Decreases the number of haematopoetic cells
What happens in anaemia of chronic disease?
The iron stored in bone marrow isn’t released, this reduces red blood cell lifespan and the marrow has a lack of response to EPO
In anaemia of chronic disease what size RBC are seen?
It can be microcytic, normocytic or macrocytic
What clinical clue can be seen in anaemia of chronic disease?
Raised CRP and ferritin
What is myelodysplastic syndrome?
Production of abnormal clones of marrow cells
In myelodysplastic syndrome what kind of anaemia develops? And why
Red cells are defective and large- macrocytic
How is diagnosis of myelodyslplastic syndrome made?
Microscopy of blood and bone marrow cells
Often genetic change at chromosomes in marrow cells
What develops in a high proportion of myelodysplastic syndrome cases?
Acute Leukaemia
Pancytopenia
What is the treatment of myelodysplastic syndrome?
Chronic transfusion
Occcasionaly chemo followed by stem cell transplant
A defficency in what building blocks of dna synthesis leads to anaemia?
Vit b12
Folate
What is seen in terms of red cells in b12 and folate defficencies and why?
Large red cel precursors with inappropriately large nuclei and chromatin
This is because nuclear maturation and cell division lags behind cytoplasmic development
What anemia do you get with b12 or folate deficency
Macrocytic
What happens to b12 in the stomach
Combined with intrinsic factor produced by patietal cells
B12 bound to intrinsic factor in the ileum does what?
B12 is absorbed and the intrinsic factor destroyed
In portal blood what is b12 bound too?
Transcoblamin
A deficency is vit b12 can be the result of what?
4
Poor diet eg vegan
Intrinsic factor- pernicious anaemia
IF-B12 complex- disease of ileum eg crohns
Transcobalmin deficent
Where does folate absorbtion occur
Duodenum and jejunum
What is dietary folate converted to
MethylTHF
When are we physiologically more likely to develop folate deficency
Pregnancy
A defficency in folate can occur due to what 4 things?
Folate defficent due to diet or increased use (haemolytic anemia, skin disease etc)
Duodenum/jejunum absobrtion issue
MethylTHF issue- some drugs inhibit this eg methotrexate
Urinary loss- liver and heart disease
What’s a pancytopenia
Low rbc, low platelets, low wbc
The peripheral blood fill in folate or b12 defficency shows what?
Macrocytic red cells with hypersegmented neutrophils
What is b12 defficency associated with that folate isn’t/
Focal demyelination
What is thalassaemia ?
Reduced rate of synthesis of normal alpha or beta globin genes
What is sick cell disease
Synthesis of abnormal haemoglobin
What mutation causes sickle
Point mutation
Valine for glutamic acid
Position 6 beta gene
What is a sickle cell crisis?
A vaso-occlusive episode that leads to organ damage.
What is the life cycle of a sickle cell like?
It’s a reversibly sickled erythrocytes but repeated cycles of deoxigantion cause irreversible sickle
What do irreversibly sickled cells do?
They have increased adherence to endothelium
They can cause thrombosis.
What kind of RBC are seen in thalassaemia?
Hypochromic
Microcytic
Why are thalassaemia cells hypochromic?
Decreased haem
How does the body try and compensate with the anaemia induced by thalassaemia?
Extramedullary haemopoeisis -results in splenomegally
Stimulation of EPO