Anaemia microcytic Part 2 Cell Abnormalities Flashcards
Describe anaemia
Reduction in haemoglobin circulating blood below what is normal for healthy person of same age and gender of an individual.
Reduction on red blood cell count RBC
And haematocrit Hct
Mechanisms that result in anaemia 4
- reduced production of red blood cells by bone marrow
- loss of blood from the body
- reduced survival of red cells in circulation (haemolysis)
- increased pooling of red cells in an enlarged spleen
Classified by mechanism and by size. Describe the sizes….
Microcytic
Macrocytic
Normocytic
What are microcytic cells?
They are small
How do we measure size of red cells
By measuring the mean cell volume of automated blood counter
What are microcytic cells like
What their cells present
They are hypochromic, very pale under the microscope.
Occasional target cells and elliptocytes
Common causes of microcytosis?
Iron deficiency anaemia
Anaemia of chronic disease
Thalassaemia
What can microcytosis be caused by?
Reduced synthesis of haemoglobin
- reduction of haem, (iron deficiency or anaemia of disease)
- reduced synthesis of globin (thalassaemia)
What are the causes of iron deficiency?
Increased blood loss
- menstrual cycle
- hookworm commonest cause worldwide
- gastrointestinal
Insufficient intake
- dietary veggie
- malabsorption- coeliac disease
- h. Pylori
Increased requirements
- pregnancy, infancy
What are the stages of iron depletion
Iron depletion
- storage iron reduced or absent
Iron deficiency
- low serum iron and transferrin saturation
Iron deficiency anaemia
- low haemoglobin and haematocrit
Clinical features of iron deficiency
Palor, fatigue and breathlessness
Failure to thrive, impaired intelectual development in children
Koilonychia, glotitis, inflammation of corners of mouth, angular dermatitis
Causes of anaemia of chronic disease? 5
Usually inflammation aspect
Rheumatoid arthiritis Autoimmune disease Malignancy Kidney disease Infections of TB or HIV
How is iron best absorbed in what form?
The Fe 2+ (animal products) ferrous is better than the 3+ (veggies) ferric
Why do we need iron homeostasis ?
No way to excrete iron by ourselves. (Little lost on skin and GI tract.
1-2mg per day
Excess is toxic to the heart and the liver
What is and what is the purpose of hepcerin?
Released by the liver
Controls absorption of iron
If amount of iron increases then so does hepcerin.
How is iron absorbed - get ready for many steps
Iron enters duodenal enterocytes
It turns into ferritin which is a storage molecule
The it passes through a transmembrane protein called Ferroportin which transports from inside to outside
This then binds to transferrin and can be transferred around the blood
Hepcedin binds here and causes internalisation - prevents influx of iron from entire site
Absorbed iron bound to ferritin and lost from body when enterocyte dies
When does hepcedin increase
In inflammation leads to low iron supply and the. Anaemia of chronic disease
Actually it leads to increased iron storage but not released into the blood and not transferred as transferrin so to be moved to erythroblasts.
Caused by increase in inflammation of interleukin 6
Lab clues for anaemia of chronic disease
C reactive protein is higher Erythrocyte sedimentation rate is high ESF (time taken for anti coagulated whole blood descend in a standardised tube over a period of time, red blood cells fall in a period of time). Increase occurs with inflammation, anaemia, pregnancy and aging Ferritin is high Transferrin is low Acute phase proteins increase
What decreases erythropoietin and pore vents normal flow of iron from the duodenum into the red blood cells
Cytokines such as TNF alpha and interleukins in chronic disease IL6 IL1 and IFN γ
This increases hepcidin and decreases iron absorption, and transport and availability
Treatment for anaemia of chronic disease
Not useful to give iron replacement therapy
Usually treat the illness by reducing inflammation but some patients benefit from erythropoietin treatment.
Compare haemoglobin MCV, Serum iron Ferritin Transferrin
Iron deficiency Low Low Low Low High
ACD Low Low Low High Low
What are the thalassaemias
Mutation or deletion of a gene encoding one of the globin chain results in reduced rate of synthesis.
Reduces rate of synthesis of haemoglobin and therefore microcytosis.
What happens in milder forms and in more advanced?
Milder forms - the bone marrow can compensate by producing more red cells so microcytosis without anaemia
In more advance cases - fatal or sustained by blood transfusion
What are the types of thalassaemias
Alpha a deletion and beta a mutation (in this we can see in electrophoresis that there is more hb A2 and more foetal hb because there is no beta globin to compensate) which affect us
Some key features in blood count
Plus some other links to the cells present in a blood film
More cells so blood count is larger
Increased RBC and normal Hb and Hct
Reduced MCV and MCH (absolute amount of haemoglobin in an individual red cell)
BUT THE MCHC (concentration of haemoglobin in a red cell- relates to shape) which is usually low is iron deficiency is normal (links to hypochromia) in thalassaemia.
The blood film may show only microcytes, or poikilocytes including target cells.
Comparison of iron deficiency and thalassaemia trait Hb MCV MCH MCHC RBC Hb electrophoresis
Iron deficiency Normal or lower Low in proportion to Hb Low in proportion to Hb Low Low Normal
Thalassaemia Normal or mildly lower Lower for same Hb Lower for same Hb Relatively preserved Increased HbA2 raised in beta thalassaemia trait but normal in alpha trait
Why is it important to distinguish thalassaemias and iron deficiency?
To replacement in iron in thallasemia has no effect
Need to advise individuals in future of potential risks in offspring (genetic counselling)
What other tests can help you distinguish these?
One is the iron stores, serum ferritin
