Normocytic and Macrocytic Anaemia + Some Blood Parameters Flashcards
How do we assess haematological parameters
Venous sample
Finger prick or heel prick sample
WBC
White blood cells in a given volume of blood x10^9 /l
RBC
Red blood cells in a given volume of blood x10^12/l
Hb
Haemoglobin concentration g/l
Hct
Haematocrit in a %
MCV
Mean cell volume fl
MCH
Mean cell haemoglobin pg
MCHC
Mean cell haemoglobin concentration g/l
Platelet count
Measured in a x10^9/l
How do we measure haemoglobin
Automated instrument
- initially measured in a spectrometer by converting into a stable state and then measuring absorption
Measuring Hct
Measured by centrifuging a blood sample and then using the scale to see the volume percentage of red blood cells in a given sample
What does polycythaemia mean
It means too many red cells in circulation
Hb RBC Hct are increased
What are the two types of polycythaemia
Pseudo- reduced plasma volume
True - increase of total volume of red cells in circulation
What can cause increase in total volume of red cells in circulation
Blood doping or overtransfusion
Appropriately increased erythropoietin - as a result of hypoxia. At high altitudes this is beneficial
Inappropriately synthesis or use of erythropoietin - when administered, or when kidney or other tumour secretes it.
Independent erythropoietin - intrinsic bone marrow disorder polycythaemia Vera. A myoproliferative disorder. Lead to thick blood and hyper viscosity and can lead to vascular obstruction and venous or arterial thrombosis. Blood can be removed by venosection. Drugs can be given to reduce production of bone marrow red cells (mutation that prevents erythropoietin to bind to the receptors, JAK2 gene time, mainly disease of the elderly)
How do we calculate MCV ?
=Hct x 1000
———————-
RBC
What are macrocytic cells?
They are larger than normal. And the MCV tends to be larger.
Always compare with what is appropriate for that age. Babies are born much larger red cells than children or adults and their cells would only be considered as macrocytic if their MCV was above a normal range in neonates.
They results from abnormal haemopoiesis so the red cell precursor continue to synthesis haemoglobin and other cellular proteins but fail to divide properly.
What are the causes of macrocytosis and anaemia
Megaloblastic anaemia
Macrocytic anaemia
Stress erythropoiesis
What is megaloblastic erythropoiesis?
Specifically delay in maturation of the nucleus, while the cytoplasm continues to mature and the cell continues to grow. Shows megalocytoplasmic dissociation.
Megaloblastic seen in the bone marrow not in the blood film
Can be caused by B12 or folate deficiency from peripheral blood features but be sure to do a bone marrow examination
What causes macrocytic anaemia?
Lack of vitamin B12 and folic acid (megaloblastic anaemia)
Use of drugs interfering with DNA synthesis
Liver disease and ethanol toxicity
Recent major blood loss with adequate iron stores (reticulocytes increased)
Haemolytic anaemia (reticulocytes increased) — young cells such as polychromatic and reticulocytes are 20% larger which means that the MCV will be increased in the blood count calculations.
Where is B12 found and how much do we need
1milligram but need 2.4 as not all of it is absorbed
Animal products
Fortified cereals
Where does deficiency result from
Veganism
Lack of acid in stomach ( is required to cleave it and release it from food in the first step)
Inadequate secretion if pernicious anaemia
Malabsorption coeliac disease
Where is folate found
Green leafy veg Cauliflower Brussels sprouts Liver kidney Whole grain cereals Yeast Fruit
How much folate do we need
50 micro grams but need to intake about 400-600
Absorbed maximally in the jejunum
Total body stores are 3-4 months
More needed in pregnancy and sickle cell anaemia
Where is folate lost from
Urine, bile cells from skin and intestine
What is the role of folic acid (a bit of extra information)
Transfer single carbon groups, essential for synthesis of purines and pyrimidines, and for inconventions of amino acids
Reduced rate of DNA synthesis, with serious pathological effects particularly in haemopoetic cells
What are the mechanisms of normocytic anaemia
Recent blood loss - trauma and GI bleeding
Failure to produce red cells - early stage of iron deficiency, bone marrow failure or suppression eg chemotherapy, bone marrow infiltration
Pooling of red cells in the spleen - hypersplenism eg liver cirrhosis and in splenic sequestration in sickle cell anaemia
How do we count reticulocytes
Stain with methylene blue which stains higher RNA content of red blood cells so they can be counted. Similiar thing for polychromasia
When is an increased reticulocyte count seen?
Haemolytic anaemia
Recent blood loss
Response to treatment with iron, B12 or folate
When is a reduced reticulocyte count seen
Reduced output of red cells from the bone marrow
What happens at the end of the life of red cells
Phagocytosed by the spleeen
Haem -> bilirubin -> excreted in bile
Iron made to transferring and returned to bone marrow
Globin -> hydrolysed to amino acids
4 mechanisms that can result to anaemia
Reduced production of red cells by the bone marrow - deficiency of iron, B12 leukamia, folate
Loss of blood from the body - GI bleeding, heavy menstrual bleeding
Reduced survival of red cells in circulation - sickle cell disease, G6PD deficiency, hereditary spherocytosis
Increased pooling of red cells in enlarged spleen - splenic sequestration in children
