7- The causes of anaemia Flashcards
1
Q
What is haemopoiesis?
A
the production of all blood cells (wbc, rbc, platlets)
2
Q
What are the main blood cells?
A
Red blood cells (erythrocytes)
white blood cells
platelets (thrombocytes)
3
Q
What is special about haemopoietic stem cells?
A
- can self renew
- ability to differentiate
4
Q
Briefly describe the haemopoietic lifecycle
A
stem cell -> multipotent progenitor cell -> commited (unipotent) progenitor cell -> precursor cell -> mature cell: RBC, WBC, platelets
5
Q
What 2 things act upon the progenitor cells?
A
- hormones
2. cytokines
6
Q
2 main lineages of hemocytoblast? (multipotential haemopoietic stem cell)
A
- common myeloid progenitor
- common lymphoid progenitor
7
Q
what does the lymphoid progenitor produce?
A
- natural killer cell
- small lymphocyte (t/b cell)
8
Q
what does the myeloid progenitor produce?
A
- megakaryocyte -> thrombocyte
- erythrocyte (rbc)
- mast cell
- myeloblast (basophil, neutrophil, eosinophil, monocyte)
9
Q
What stimulates a megakaryocyte?
A
thrombopoietin to produce thrombocytes (platelets)
10
Q
What stimulates erythrocyte production?
A
erythropoietin
11
Q
Where does haemopoiesis take place?
A
bone marrow in red marrow
12
Q
5 main white blood cells?
A
- lymphocytes
- basophils
- neutrophils
- eosinophils
- monocyte
13
Q
myeloid progenitor how many wbc?
A
4/5
14
Q
lymphoid progenitor how many wbc?
A
1/5
15
Q
what is erythropoiesis
A
production of erythrocytes
16
Q
erythrocyte cycle?
A
hemocytoblast -> proerythroblast -> early erythroblast ->late erythroblast -> normoblast (nucleus is ejected) -> reticulocte -> erythrocyte
17
Q
What does a reticulocyte or normoblast present in blood suggest?
A
anaemia or red blood cell production problems
18
Q
What does the term “blast” mean?
A
they are precursor cells and should only be found in bone marrow
19
Q
When are reticulocytes released into circulation?
A
if RBC count is low
20
Q
What is the shape of erythrocytes?
A
biconcave disc
21
Q
What is the diameter of an erythrocyte?
A
7-8 micrometres
22
Q
How do erythrocytes fit into capillaries?
A
they are flexible so fold into an arrowhead to fit
23
Q
What are the cellular contents of erythrocytes?
A
Main component haemoglobin to carry oxygen
no organelles
24
Q
What is the function of erythrocytes?
A
- carries O2 to be delivered to cells
- carries CO2 to be removed
25
What is the lifespan of an erythrocyte?
120 days
26
Why is the lifespan of an erythrocyte only 120 days?
membrane quite fragile, constantly squeezing into small blood vessels eventually breaks down in the spleen
27
Where do erythrocytes break down?
in the spleen and liver
28
What breaks down erythrocytes?
Macrophages
29
What is globin recycled into?
amino acids used for general protein synthesis
30
What is haem recycled into?
- into iron to be used in erythropoiesis
| - converted into bilirubin becomes bile excreted
31
What are the WHO classifications of anaemia?
men haemoglobin less than 13g/dL
| women haemoglobin less than 12 g/dL
32
What is the definition of anaemia?
Low levels of haemoglobin in the blood
33
What are the main causes of anaemia?
1. Blood loss
2. Impaired erythrocyte production
3. Excessive erythrocyte destruction
34
What does anaemia cause morphological changes in?
- size
- shape
- colour of red blood cells
35
What does hypochromic mean?
RBC paler due to lack of haemoglobin
36
What does normochromic/normocytic mean?
Normal colour, normal size
37
What does microcytic mean?
Smaller than normal rbc (smaller mcv)
38
What does macrocytic mean?
Larger than normal rbc (greater mcv)
39
What are some signs and symptoms of anaemia?
1. pale
2. fatigue
3. dyspnea (shortness of breath)
4. palpitations
5. headache
6. tinnitus
7. anorexia and bowel disturbance
40
What is the bodies physiological response of anaemia?
- 2,3 DPG levels rise
| - Cardiac output increases
41
What does mcv mean?
Mean Cell Volume
42
What is 2,3 DPG levels?
A substance produced by RBC to help oxygen bind/upload to the tissue. It decreases the affinity to oxygen so that it is more easily given up
43
How much iron is present in 500ml of blood?
200-250mg
44
2 types of blood loss?
1. Acute: loss of large volume of blood e.g. trauma
| 2. Chronic: bleeding unnoticed over a period of time
45
What deficiencies can cause impaired erythrocyte production?
- iron
- vitamin B12
- folate
46
What is the daily iron cycle?
the circulation of iron in the body,
47
How does iron circulate in the plasma?
Bound to transferrin
48
What does transferrin do?
Delivers iron to tissues that have transferrin receptors
49
How much iron do transferrin receptors have at any given time?
4mg
50
How much iron do we absorb per day in the gut?
1mg
51
How much iron should we have in our diet?
10-20mg
52
Where is iron absorbed?
Upper GI tract
53
What is iron needed for?
Synthesis of haemoglobin
54
What type of anaemia is iron deficiency
Microcytic
55
What are potential causes of iron deficiency?
1. increased physiological demands - (growth spurt/pregnancy)
2. chronic blood loss
3, inadequate intake
4. coeliac disease/ chrons disease ( malabsorption)
56
How does coeliac cause iron deficiency?
Impacts gastric mucosa, affects iron transporters, therefore, iron not being taken up even if meeting daily requirement
57
Clinical signs and symptoms of iron deficiency
1. Koilonychia (spooning of nails)
2. Angular stomatitis (lesions at corner of the mouth)
3. Glossitis
4. Pallor of skin + increased fatigue
58
Laboratory findings of iron deficiency?
- haemoglobin concentration decreased
- mcv reduced (microcytic cells)
- Hematocrit reduced
59
What type of anaemia is Vitamin B12 deficiency?
Macrocytic
60
Where is B12 found?
red meats but not vegetables
61
what does b12 require in order to be absorbed?
intrinsic factor (found in parietal cells of stomach)
62
Where is B12 absorbed in the GI tract?
Terminal ileum in GI tract
63
main cause of b12 deficiency?
- malabsorption (gastric diseases cause loss of intrinsic factor)
- Increased demands
64
Causes of B12 deficiency anaemia?
- inadequate diet (Vegans)
- increased demands
- deficiency of intrinsic factor
- intestinal causes affecting absorption (infection/loss of absorptive surfaces)
- drugs preventing absorption
65
Laboratory findings of b12 deficiency anaemia
- increaed mcv (macrocytic)
| - thymidine deficiency
66
What is thymidine?
needed for DNA synthesis and nuclear maturation
67
What type of anaemia is folate deficiency?
Macrocytic
68
Where is folate (folic acid) found?
leafy veg
69
where is folate absorbed in GI tract?
upper GI tract
70
what are the causes of folate deficiency?
- malabsorption
- increased demands
- inadequate diet
- alcoholism (affects gi mucosa)
- antifolate drugs
71
What other things cause impaired erythrocyte production?
- chronic inflammation (affects bone marrow)
- chronic renal disease (affects kidneys)
- aplastic anaemia
- infiltration of marrow by leukaemia/lymphoma/carcinoma
- drug induced
- irradiation
72
what is aplastic anaemia
autoimmune disease causing deficiency of all blood types
73
3 main reasons of excessive erythrocyte production
1. intracorpuscular defects
2. extracorpuscular defects
3. haemolytic anaemia
74
Name some intracorpuscular defects?
1. abnormal haemoglobin
2. erythrocyte membrane defects
3. enzyme defects
75
What are intracorpuscular defects usually?
inherited (within RBC)
76
What type of haemoglobin does sickle cell produce?
haemoglobin S
77
what is the issue with producing haemoglobin s?
forms polymers in red blood cell so it doesn't give up oxygen easily, causes rbc to change to sickle shape
78
What happens in thalassemia?
absence/reduction in one of the haemoglobin chains
79
how many chains do we have in haemoglobin normally?
- 2 alpha
| - 2 beta
80
2 types of erythrocyte membrane defects?
1. hereditary spherocytosis- cell becomes spherical, gets stuck easily so broken down prematurely
2. Elliptocytosis - becomes pencil shaped
81
example of an enzyme defect causing excessive erythrocyte destruction?
G6PD needed in glycolysis impacts the way a RBC survives
82
Name some extracorpuscular defects that cause excessive erythrocyte destruction?
1. immune (haemolytic disease of the newborn)
2. incompatible blood transfusion
3. drug induced (can break down rbc prematurely)
4. infection (pneumonia, malaria)
5. idiopathic (spontaneous unknown cause)
6. mechanical (prosthetic valves)
7. burns
83
What are extracorpuscular defects usually?
Acquired (outside rbc)
84
what is haemolytic disease of the newborn?
incompatibility with rhesus blood group
85
What are clinical features of patients with anemia?
- pallor
- tiredness/lethargy
- shortness of breath
- glossitis
- angular stomatitis
- oral ulcers
86
What is leukaemia?
Increased white cell count, reduced red blood cell and platelets
87
Main steps for investigation for anaemia?
- full blood count
- blood film picture
- bone marrow failure
- ferritin and iron-binding capacity
88
Why is anaemia important to dentist?
- anaemia may be obvious on examination
- may be a feature of infection (bleeding, easy to bruise)
- important to investigate, it is a symptom of a disease, important to find out actual cause
