ELFH Bleeding Disorders of Importance in Dentistry Flashcards
1
Q
The most common hematological conditions are?
A
Anaemia
Haemolytic anaemia
Myeloproliferative and dysplastic disorders
Haematological malignancies
Blood transfusion
Bleeding disorders
Thrombosis
2
Q
haematopoiesis?
A
formation of blood cells, and bone marrow is the source of this process.
3
Q
What are the two main second generation stem cell groups?
A
- lymphoid
- myeloid
4
Q
lymphoid cells?
A
give rise to B or T cells
5
Q
myeloid cells?
A
give rise to
- neutrophils, eosinophils, monocytes, basophils
- RBC
- Platelets
6
Q
what is the main control of red cell formation?
A
juxta-glomerular apparatus derived erythropoietin.
7
Q
What is anaemia?
A
decrease in haemoglobin (Hb)
8
Q
level of Hb for anemia in women?
A
<11.5 g/dl for women
9
Q
level of Hb for anaemia on men?
A
<13.5 g/dl for men
10
Q
signs and symptoms of anaemia can be reflected in what biologically?
A
reflect the inability of the body cells to make sufficient ATP to carry our cellular function.
11
Q
what cells are more susceptible to the effects of anaemia?
A
heart and brain
12
Q
how do blood values reflect anaemia?
A
Blood values reflect this with a low Hb and usually a low red cell count.
13
Q
clinical features of anaemia?
A
- Fatigue, fainting (tendency), headaches, vertigo
- Loss of appetite, weight loss, nausea
- Breathlessness
- If there is a pre-existing cardiovascular disease, then angina and claudication could result in cardiac failure
- Pale skin and mucous membranes, conjunctivae
- Increased heart rate (pumping the remaining oxygen around faster), palpitations
14
Q
oral symptoms of anaemia?
A
- Angular cheilitis
- Glossitis (Fig 2)
- Burning mouth/tongue
- Apthous ulcers
- Oral candidiasis
- Delayed wound healing
15
Q
Causes of anaemia are usually explained by the size of the resultant (MCV)
name the classifications of MCV?
A
MICROCYTIC
MACROCYTIC
NORMOCYTIC
16
Q
microcytic?
A
red cell is <80 fl in size and is usually associated with reduced intra-cellular haemoglobin (Hb), which creates a hypochromic appearance
17
Q
macrocytic?
A
reflects an increased MCV but with reduced Hb level
18
Q
normocytic?
A
the Hb is low but the MCV is within normal limits
19
Q
MCV nrmla limits?
A
80-96 fl
20
Q
Causes of normocytic anaemia are?
A
- Cancer e.g. lymphoma
- Chronic diseases such as rheumatoid arthritis, inflammatory bowel disease and renal problems, osteomyelitis
- Chronic infections, such as tuberculosis
21
Q
causes of microcytic anaemia?
A
Iron deficiency
Anaemia of chronic disease
Sideroblastic anaemia
Thalassaemia
22
Q
stored form of iron?
A
ferritin
23
Q
where is iron stored?
A
muscle
liver
marrow
24
Q
do we naturally lose iron every day?
A
yes
Humans lose 1 mg of iron per day in skin, sweat, urine and faeces
25
Do you know what the most common causes of iron deficiency anaemia are in the UK?
Menstruation
GI blood loss, chronic which needs investigation
Increased demand, growth and pregnancy
Small bowel disease leading to reduced absorption
Poor diet (rare in west)
these cause iron deficiency which causes microcytic anaemia
26
Clinical features are as described previously in this session, but in addition there is an association with what?
- Brittle hair and nails
- Spoon shaped nails (koilonychia) (Fig 1)
- Patterson-Kelly syndrome (pharyngeal web and dysphagia)
27
How is iron carried in the blood?
on transferrin
28
iron deficiency anaemia increases or decreases the total iron binding capacity of transferrin?
increased binding capacity
however there is low ferritin
29
Management of iron deficiency anaemia?
Find and treat the cause
Oral iron, ferrous sulphate
IM only when intolerance or malabsorption
30
Why does chronic inflammatory conditions such as inflammatory bowel disease, rheumatoid arthritis, tuberculosis, osteomyelitis and chronic renal failure lead to anaemia?
The inflammatory mediators inhibit the release of iron to the developing red cells (erythroblasts), as well as reduced erythropoietin.
In addition, the red cells survive for a shorter length of time. It can present with a normocytic picture but it is commonly microcytic with low HgB and low MCV.
Anaemia of chronic disease also leads to low serum iron, low ferritin and raised TIBC (transferrin).
31
what is sideroblastic anaemia?
a type of microcytic anaemia
Sideroblastic anaemia is rare and associated with dysfunctional haem synthesis.
It is characterised by ring sideroblasts (Fig 1), which are immature red cells, and erythroblasts with iron in the mitochondria, reflecting an inability to utilise the iron.
32
How would you get sideroblastic anaemia?
it may be inherited but most develop following exposure to toxins, drug induced including alcohol, nutritional, connective tissue disorder (RA)
OR genetic disorders.
33
management of sideroblastic anaemia?
Management includes withdrawing the causative agent and vitamin B6, however, it may require a transfusion.
34
What is thalassaemia?
normal haemoglobin is composed of aloha and beta chains (2xA 2xB)
In the absence of beta chains (due to mutation), synthesis reverts to other forms
- HbA2 (alpha x 2, delta x 2)
- HbF (alpha x 2, gamma x 2, which is fetal haemoglobin)
35
alpha-gamma haemoglobin is what?
foetal haemoglobin
36
alpha thalassaemia?
Reduced alpha chain - alpha thalassaemia
is common but either results in death in utero(x4 alpha chains missing) or is mild and symptomless
37
beta thalassaemia?
Reduced beta chain - beta thalassaemia
there is a deposition of intracellular globin and interference of red cell function and subsequent haemolysis.
Beta thalassaemia affects the beta chains, causing an alpha chain excess and increased HbA2 and HbF.
38
who is more likley to inherit thalassaemia?
It is often found in Middle East Asia and Mediterranean regions.
39
3 main forms of beta thalassaemia?
beta thalassaemia major
beta thalassaemia intermedia
beta thalassaemia minor
40
beta thalassaemia major?
Homozygous loss of beta chain genes.
Causes severe anaemia from birth with infections, failure to thrive and abnormal bone marrow function
leading to expanded bone abnormalities, e.g. enlarged maxilla, frontal bones, typical thalassaemic face (chipmunk), activated haematopoesis in the liver and spleen (normally in fetus only).
41
effect of beta thalassaemia major on skull formation?
enlarged maxilla, frontal bones, typical thalassaemic face (chipmunk)
42
beta thalassaemia intermedia?
Moderate anaemia (Hb 7-10 g/dl) and does not require regular transfusions but the patient may develop an enlarged spleen, bone deformity and gallstones.
43
Beta thalassaemia minor?
Asymptomatic heterozygous (one globin gene affected) which causes mild anaemia with microcytic picture and normal iron and ferritin levels.
44
how to confirm thalassaemia?
haemoglobin electrophoresis, showing increased HbF and much reduced HbA.
45
management of thalassaemia?
Severe cases will require transfusions to keep Hb above 10 g/dl, but it is associated with iron overload which damages the liver, pancreas and heart - this can be prevented by chelating agent desferrioxamine.
A bone marrow transplant is used in some cases.
46
desferrioxamine?
a medicine that removes excess iron that builds up after a period of time on regular blood transfusions
47
excess iron affects what organs?
heart
liver
spleen
48
challenges of dental tx and thalassaemia?
challenging in homozygous children, with facial swelling and deformities, as well as infection challenges.
Severe anaemia may present with oral symptoms and will pose a challenge if sedation is considered and will require hospital-based care.
49
causes of macrocytic anaemia?
megaloblastic
normoblastic (macrocytic)
50
reasons for megaloblastic? (macrocytic)
(Bone marrow red cells with immature nuclei compared to the cytoplasm)
- Vit B12 deficiency
- Folate deficiency
51
reasons for normoblastic? (macrocytic)
- Haemolysis
- Chemotherapy e.g. hydroxycarbamide and azothioprine
- Myelodysplasia
- Hypothyroidism
- Alcohol excess
- Liver disease
- Aplastic anaemia
52
underlying defect in megaloblastic anaemia?
defective DNA synthesis, which requires both vitamin B12 and folate for normal synthesis.
53
does foliate an dB12 deficiency affect other cells?
yes
White cells (hypersegmented neutrophil and leucopenia)
platelets (thrombocytopenia) may also be affected.
54
main causes of B12 deficiency?
- Pernicious anaemia (most common cause in the UK)
- Gastrectomy
- Diet (vegans)
- Lieal resection
- Coeliac disease
- Bacterial overgrowth (uses the B12 to synthesis its own DNA)
55
most common cause of vitamin B12 deficincy uk?
Pernicious anaemia
56
where is B12 stored?
liver
57
Pernicious anaemia?
autoimmune reaction against IF and parietal cells
It is common in elderly women and associated with other autoimmune diseases such as vitiligo and thyroid disease.
58
journey of B12 to then be stored in the liver?
Vitamin B12 is found in meat and dairy products
which after release is bound to intrinsic factor (IF) released from the parietal cells (as well as acid) in the stomach.
This complex is then absorbed in the terminal ileum, and bound in the plasma to transcobalamin.
Stores in liver last up to two years
59
causes of folate deficiency?
- Dietary - more likely especially in the elderly, alcohol abusers, poverty
- Malabsorption with small bowel disease such as coeliac
- Overuse e.g. pregnancy, chronic haemolytic anaemia, malignancy and inflammatory diseases
- Drugs such as phenytoin and trimethoprim
60
management of folate deficiency?
folate tablets every day (5 mg - four months minimum if underlying cause treated) can be prescribed.
Folate supplements are given during pregnancy to prevent neural tube defects.
61
symptoms of pernicious anaemia?
slow onset and symptoms
include glossitis, angular cheilitis and, due to fragility of the larger red cells, mild jaundice.
The patient may even develop polyneuropathy.
Even the optic nerve may be affected.
62
blood test results with pernicious anaemia?
Bloods reveal a low Hb, large MCV(>110 fl), hypersegmented neutrophils and, if severe, leucopenia and platelets.
Serum B12 is low and red cell folate is also low as B12 is needed to convert folate.
Anti-parietal cell (90%) and anti IF Abs (50%). Raised bilirubin (Hb breakdown increased).
63
management of pernicious anaemia?
Pernicious anaemia is managed with IM hydroxo-cobalamin (B12) every three months for life.
There has also been recent benefits with high dose oral B12 (cobalamin).
64
haemolytic anaemia?
This group of disorders are linked by their description of an increased destruction of red cells and reduced survival (an average of three months), which are then usually removed by the spleen.
65
causes of haemolytic anaemia?
inherited
acquired
66
inherited haemolytic anaemia?
Red cell membrane defects e.g. hereditary spherocytosis
Haemoglobin disorders e.g. thalassaemia and sickle cell disease
Red cell metabolism defects such as glucose 6 phosphate dehydrogenase and pyruvate kinase deficiencies
67
acquired haemolytic anaemia?
- immunological, e.g. autoimmune, blood transfusion or drug induced haemolytic anaemia
- Non-immune such as paroxysmal nocturnal haemoglobinuria
- Others, e.g. infections (malaria) and drugs
68
what characterises cell membrane defects in haemolytic anaemia?
hereditary spherocytosis
69
hereditary spherocytosis?
AD problem which reflects a weakened RBC membrane due to a defect in the protein spectrin.
As a result, the cells become rotund and less malleable and rupture on their journey through tight spaces such as the spleen
70
presenting features of inherited haemolytic anaemia?
Jaundice
Anaemia
Splenomegaly
Ulceration (legs)
In time, the patient may also develop pigment gall stones. Crises are possible which may be infection-induced aplastic and folate consuming megaloblastic.
71
how to confirm haemolytic anaemia diagnosis?
with blood film (spherocytes) and anaemia with reticulocytosis.
72
management of haemolytic anaemia?
In young adulthood, a splenectomy may be requied which needs a lifetime of prophylactic penicillin and vaccination against pneumococcal infection.
73
sickle cell anaemia occurs when?
both genes are defective (homozygous)
74
what gene is inherited in sickle cell disease?
HbS
75
sickle cell trait occurs when?
one gene is defective (heterozygous) the disorder is sickle cell trait
76
what occurs in sickle cell disease?
When deoxygenated, the sickle Hb precipitates and the red cell becomes rigid and sickle in shape, causing haemolysis and vascular occlusion, leading to tissue infarction
77
clinical features of sickle cell anaemia?
haemolysis
vaso-occlusion - following infection
78
management option for sickle cell?
Bloods will reveal low Hb (6-8 g/dl), increased reticulocyte count and sickle red cells on film view. Hb electrophoresis will show HbSS and missing HbA.
A Sickle crisis is managed with analgesia (NSAIDS and opiates), oxygen, rehydration and a search for the source of sepsis. Folic acid should be recommended for patients who haemolyse frequently and to pregnant patients.
Exchange transfusions may be required.
Mean survival of patients with sickle cell is 40-50 years.
Sickle patients need appropriate work up before general anesthesia.
79
re cell metabolism defects and haemolytic anaemia?
Glucose-6-phophate dehydrogenase deficiency is vital to maintain glutathione in a reduced state to help the movement of electrons (H) through the metabolic pathways (oxidation).
In its absence the membrane becomes damaged and fragile and can rupture which leads to haemolysis and jaundice
80
immunological haemolytic anaemia? acquired causes
e.g. autoimmune, blood transfusion or drug-induced haemolytic anaemia
81
non-immune haemolytic anaemia? acquired causes
such as paroxysmal nocturnal haemoglobinuria
82
how to manage immunological haemolytic anaemia?
steroids in high doses, splenectomy and possibly immunosuppressive drugs such as azothioprine.
83
management of non-immunological haemolytic anaemia?
Supportive treatment is required but a bone marrow transplant may be necessary.
84
myeloproliferative disorders?
disorders reflect an overproduction of one of the myeloid cell lines producing red or white cells and platelets. There is a risk of myeloproliferative disorders developing into acute myeloid leukaemia (AML).
e.g. Polycythaemia
85
Myelodysplasia
refers to disorders arising from defective bone marrow stem cells which undergo premature cell death (apotosis) leading to bone marrow failure, leucopenia, anaemia and thrombocytopenia. There is a risk of acute myeloid leukaemia.
86
Polycythaemia? (myeloproliferative disorders)
Polycythaemia is characterised by an increased red cell count and increased Hb. Primary polycythaemia is due to direct overproduction of the red cells due to clonal expansion of the erythrocytic precursors. Plasma reduction will give a secondary, relative increase.
The drive for primary (absolute) PCT comes from an overproduction of erythropoeitin either due to hypoxia (smoking), a tumour (renal, liver or brain) or lack of normal control.
The latter is known as PCT vera.
87
Blood contains a number of different aspects which may be required for transfusions?
- Whole blood (rarely used)
- Packed red cells used for acute blood loss and anaemia
- Platelet concentrates for platelet-related bleeding problems
- Fresh frozen plasma for coagulation factor problems
- Cryoprecipitate is obtained when FFP is frozen and thawed, contains fibrinogen, factors VIII, XIIII and vWF
- Albumin for hypoalbuminaemia
- Immunoglobulins, e.g. after exposure to infection such as hepatitis B or for patients with hypogammaglobulinaemia
88
who is the universal blood donor?
O
(rh -ve)
89
who is the universal blood recipient?
AB - rare
90
antibooes to blood group?
e.g. A blood group, pt has B antibody
91
affects of ABO mismatch?
Immediate haemolysis, hypotension and dyspnoea.
Transfusion must be stopped immediately.
92
Complications that can occur during transfusions include?
ABO mismatch
anaphylaxis
infection
febrile reaction
cation level changes
heart failure
platelet loss
93
acute anaphylaxis?
Acute anaphylaxis is caused by anti-IgA antibodies and needs emergency management, including stopping the transfusion.
94
febrile reaction?
Caused by antibodies (recipient) against white cells (donor) releasing pyrogens.
95
Who is at risk of arterial thrombi?
atheromataous disease are at risk
lead to infarction of dependent organs and result in problems such as MI or strokes. Patients will therefore take a range of drugs designed to prevent or to treat thrombi.
96
drugs from thrombus?
aspirin
clopidogrel
dipyridamole
97
aspirin?
inhibits Thromboxane A2 synthesis and inhibits platelet aggregation
98
Dipyridamole?
inhibits platelet aggregation by preventing intra-platelet phosphodiesterase breakdown of cyclic AMP
99
clopidogrel?
also inhibits platelet aggregation by preventing ADP from binding to its receptor
100
abciximab?
Antibodies may block the platelet GPIIb/IIIa receptor and prevent activation (abciximab).
binds to the glycoprotein (GP) IIb/IIIa receptor of human platelets and inhibits platelet aggregation by preventing the binding of fibrinogen, von Willebrand factor, and other adhesive molecules.
101
B. False. This is used for venous thrombosis.
C. False. This is used for venous thrombosis.
102
venous thrombosis cause?
associated with periods of immobility and dehydration.
Hospital patients are obviously at risk especially if undergoing long surgical procedures, but everyday events such as aeroplane journeys appear to carry the same risk.
occurs in normal vessels e.g. deep veins of leg
103
symptoms of obstruction of venous drainage?
swelling, pain and heat and a deep vein thrombosi
104
where does the danger lie with thrombosis?
The danger lies in the fragment which may embolise.
105
prevention for venous thromboses?
The main prevention is to encourage movement and hydration whilst in the immobilised environment. In addition, hospital patients can wear thromboembolic deterrent (TED)stockings.
Low molecular weight heparins (clexane, enoxaparin) given subcutaneously will, by activating antithrombin III, provide protection.
106
treatment for venous thrombosis?
If thrombus has formed, or even embolised, to cause a pulmonary embolism then the following should be used for treatment:
IV heparin (bleeding and reduced platelets are side effects)
Replace with subcutaeous heparin, check activity with APTT
Oral warfarin (inhibits vitamin K dependent gamma carboxylation of factors II,VII, IX and X) for 6 months ( INR at 2.5, and re-explore to see if thrombus has resolved
107
108
C. Correct. Vitamin B12 and folate are important in DNA synthesis.
