Basics Flashcards
What are some of the possible causes of low cell count?
Blood loss
Haemolytic anaemia
Bone marrow abnormalities
Chronic disease
What are some of the causes of high cell count?
Infection
Malignancy
Steroids
What terms are used to describe excess in haematology?
Cytosis or philia
What term is used to describe shortage in haematology?
Penia
Where does haematopoiesis occur in the embryo?
Yolk sac, then liver, then marrow
Spleen in the 3rd - 7th months
In an adult, where is the common site for bone marrow aspiration and biopsy?
Posterior iliac crests
What happens to the nucleus as red blood cells mature?
As the cell matures it loses its nucleus, once it leaves the bone marrow into the circulation it leaves the nucleus behind
Which granulocyte is a polymorph with a segmented nucleus and has neutral staining granules?
Neutrophils
Which granulocytes is usually bi-lobed and has bright orange/ red granules?
Eosinophils
Which granulocytes has large deep purple granules which obscure the nucleus?
Basophils
Which type of granulocyte is a circulating version of a tissue mast cell and mediates hypersensitivity reactions? This cell type has Fc receptors which bind IgE and granules which contain histamine.
Basophils
Which cell type circulates for a week before entering tissues to become macrophages?
Monocytes
These phagocytose invaders and attract other cells
Which cell type cognates responses to infection and ccan thus be considered the ‘brains’ of the immune system?
Lymphocytes
What is Hb called when it is oxidised with Fe3+?
Methaemoglobin
Can’t carry oxygen in this state
What does the RBC do for energy production?
Relies on glycolysis for energy production as it has no mitochondria
Why do red blood cells have a limited lifespan?
They have no nucleus so can’t divide or replace damage
What happens to the levels of erythropoietin in hypoxia?
Erythropoietin levels rise in hypoxia
How is hypoxia sensed and what happens as a consequence?
Interstitial fibroblasts in the kidneys detect hypoxia in the blood flowing through the kidneys
This results in increased production of erythropoietin
How does an increase in levels of erythropoietin levels in conditions of hypoxia act to increase red blood cell production?
Erythropoietin stimulates cell division red cell precursors and recruits more cells to the marrow
The result is erythroid hyperplasia (more machinery to produce RBCs)
What are red blood cells called for the first few days after production?
Reticulocytes
Worn out red blood cells are recycled into raw materials. What are these raw materials?
Iron, amino acids, bilirubin
Where does red cell destruction usually occur?
Spleen
How are aged red blood cells taken out of the circulation?
They are taken up by macrophages
Describe how red blood cell contents are removed/ recycled
Globing chains are made into amino acid
Heme is broken down into iron and bilirubin
Bilirubin is taken to the liver, conjugated and then excreted in bile
At the same p02, do HbF and myoglobin bind more or less oxygen than normal Hb?
At the same p02, both HbF and myoglobin can bind more 02
What happens to the levels of 2,3 DPG in chronic anaemia?
2,3 DPG is increased in chronic anaemia
How is most carbon dioxide transported?
Most carbon dioxide is transported as bicarbonate (60%)
10% is dissolved in solution
30% is bound directly to Hb as carbamino Hb
Reactive oxygen species such as hydrogen peroxide are free radicals which have unpaired free electrons and can damage haemoglobin. How does glutathione counteract this?
Glutathione reacts with hydrogen peroxide to form water and oxidised glutathione product GSSG
What does the Rapapoport Lubering shunt do?
Generates 2,3 DPG that shifts the oxygen dissociation curve to the right and allows more oxygen to be released
What does the Embden-Myerhof pathway do?
Anaerobic glycolysis pathway
Reverses Fe3+ to Fe2+
How much iron is absorbed and lost per day?
1mg absorbed and 1mg lost
Where does iron absorption mainly occur?
In the duodenum
What things enhance or inhibit iron absorption?
Enhance iron absorption;
- Ascorbic acid
- Alcohol
Inhibit iron absorption;
- Tannins (e.g tea)
- PPIs
What is the role of ferroportin?
Facilitates iron export from cells
Iron is then passed on to transferrin to be transported elsewhere
What is the role of DMT (divalent metal transporter)?
Transports ferrous iron into the duodenal enterocyte
What is the role of duodenal cytochrome B?
Reduces ferric iron (Fe3+) to ferrous form (Fe2+)
What is the role of hepcidin?
It is the major negative regulator of iron uptake
It binds to ferroportin and causes its degradation
Produced in the liver in response to iron load and inflammation
Different tests can be done to assess iron status. What is used to measure functional iron?
Haemoglobin concentration
Different tests can be done to assess iron status. What is used to measure transport iron (iron supply to tissues)?
Transferrin saturation (saturation is normally 20-50%)
Different tests can be done to assess iron status. What is used to measure storage iron?
Serum ferritin
What is hereditary haemochromatosis?
An inherited condition involving decreased synthesis of hepcidin and thus iron loading
Hereditary haemochromatosis can be caused by several different mutations but what is the most common?
Mutations in the HFE gene
What would be the expected results of transferrin saturation and serum ferritin measurement in hereditary haemochromatosis?
Transferrin saturation >50%
Serum ferritin >300ug in men/ 200ug in women
How is hereditary haemochromatosis managed?
Weekly venesection
Family screening
Venesection is not a suitable treatment option for patients with secondary iron overload if they are already anaemic. What other management options can be considered?
Iron chelating agents - deferrioxamine- subcutaneous or IV
Deferiprone/ deferasirox - oral gents
