Haematology Flashcards
(35 cards)
Define Haematopoiesis, Outline what areas of the body make up the Haematopoietic System and compare Childhood v Adult Haematopoiesis
The process via which all blood cells are produced is known as Haematopoiesis.
The process starts with a Haemocytoblast, which is a pluripotent stem cell capable of self -renewal and differentiation into 2 main cell lines (myeloid progenitor and lymphoid progenitor).The main 2 areas in an adult where this occurs is in the bone marrow of the axial skeleton and proximal parts of long bones and the spleen. In a child it will also occur more extensively in bone marrow of nearly all bones, as well as liver, thymus and lymph nodes, whose activity will become more/less important with age.
What are the two main measures taking in regards to RBCs and what are their healthy ranges?
Haemaglobin Levels. Adult male 130-170g/L. Less in women, and children, even less in pregnant women
MCV. This is the average volume of each RBC. Normal range is 80-95fL (femtolitres)
Define Anaemia.
Refers to any reduction in Haemaglobin levels below the reference range for the age and sex of the individual.
Outline the main general Signs/Symptoms of Anaemia.
What does the severity if them tell us?
Symptoms: Lassitude + Fatigue Breathlessness on exertion Palpitations Headaches Chest Pain
Signs Pallor (seen on FOM and conjuctiva) Tachychardia Wide pulse pressures Flow murmurs Congestive cardiac failure (late sign)
Fewer and less severe s/s a patient has, the slower the progression and the more subtle their anaemia likely is.
What are the 5 classifications of anaemia by mechanism?
- Sufficient Blood Loss
- Haemolytic RBCs (may be congenital i.e. sickle cell anaemia or acquired i.e. malaria/drug induced)
- Insufficient/Ineffective Erythropoiesis
- RBC pooling and destruction in Spleen
- Physiological anaemia (i.e. in pregnancy plasma volume increases on a larger scale than RBCs leading to ‘haemodilution’ and anaemia.
What is the classification by morphology and give MCV ranges for each.
Microcytic anaemia MCV<80
Normocytic anaemia, normal MCV
Macrocytic anaemia MCV>95
What are the two common causes of Microcytic Anaemia?
Fe deficiency anaemia and Thalassaemias
Why does body tightly control Fe absorption?
What are the 3 main mechanisms by which Fe deficiency anaemia occurs giving examples?
Because Fe in excess is potentially toxic
Insufficient dietary intake (vegans/vegetarians lol)
Malabsorption (i.e. in duodenum due to coeliac disease)
Increased loss (commonly mennorhagia in or GI causes-peptic ulceration, IBD, hookworm) But don't be satisfied with these reasons as Malignancies also a major cause of unexplained Fe defiency anaemia.
Main s/s of Fe deficiency anaemia?
Those with mild deficiency will be asymptomatic
More severe/faster progressing cases will have:
Koilonychia (thin spoon shaped nails)
Orally: Angular Cheilitis Atrophic Glossitis (atrophy of lingual papillae leaving smooth tongue, tender and painful. Recurrent ulceration Burning mouth
Oesophageal Web
Outline the management and treatment for Fe deficiency anaemia?
Who are the red flag patients?
In managing: first try and identify the cause.
Red flag patients are 50+ men and post-menopausal women with unexplained Fe- def’ anaemia
When treating, adress underlying cause.
Give oral supplementation of Ferrous sulphate 200mg TDS for 3/12 the reassess.
If necessary, parenteral administration available.
What is Thalassemia?
How is it diagnosed?
Common genetic disorder which affects the alpha or beta chain structure of Hb.
Diagnosed by Hb Electrophoresis.
Compare alpha and beta thallasemia in terms of geographic prevalence. What happens to the genes?
Alpha seen in SE asia and w africa. Deletion of alpha-globin genes. The more are deleted, the more severity increases from mild MCV reduction to in utero/neonatal death. Deletion of 2 or less genes is considered a trait. 3/4 is considered disease.
Beta thalassaemia is seen more commonly in southern europe especially Greece.
Due to gene mutation. Heterozygous trait will be asymptomatic. Homozygous sufferer will have moderate/marked anaemia which develops from 0-2 yrs of age.
Outline the 4 stage clinical classification Thalassaemia
Minima-presence of genetic disorder. No clinical consequence
Minor- RBCs microcytic and hypochromic
Intermedia- as above plus extramedullary haematopoiesis and sphlenomegaly
Major- as above plus severe anaemia and transfusion dependency
What are the clinical presentations seen in severe thalassaemia?
How would a skull x-ray appear?
What is the main concern in a transfusion dependent patient?
Untreated th’ leads to growth retardation, sphlenomegaly and bony deformities due to marrow expansion.
Patient will have enlarged maxilla (chipmunk face)
Spaced out upper anterior teeth.
Skull X-ray would show: Hairs on end appearance
Delayed pneumatisation of maxillary sinuses and ‘chickenwire’ appearance of alveolar bone.
Main concern is iron overload leading to Fe accumulation in myocardium, liver, pancreas and salivary glands.
What are the main causes of Normocytic anaemia?
Acute blood loss, chronic inflammation/infection/renal disease, malignancies
How does chronic inflammation/infection/renal disease cause Normocytic Anaemia?
Infection/Inflammation/Disease cause immune system to make 4 main changes.
- It makes the use and storage of iron less efficient.
- It can cause the kidneys (especially in anaemia due to chronic renal disease) to produce less erythropoietin (EPO) hormone require to signal process in bone marrow.
- the bone marrow can respond abnormally to EPO
- lastly RBCs themselves can become haemolytic and die at a faster rate than they are replenished.
Macrocytic Anaemia can be divided into what two groups based on Erythropoiesis?
Megaloblastic erythropoiesis where disordered DNA synthesis leads to abnormal RBC development.
Normoblastic erythropoiesis where everything is normal up till point of maturation. i.e.. blast is normal.
Why do we need folate?
What are the 5 causes of folate deficiency leading to normocytic anaemia?
Folate is essential for DNA synthesis
Deficiency causes inc:
Inadequate intake
Malabsorption (coeliac disease, jejunum resection)
Increased requirement (pregnancy, haemolytic anaemias)
Increased loss (liver disease, dialysis)
Drugs (methotrexate, this is an immunosuppressant drug which causes increased folate excretion, so folic acid normally prescribed alongside it. Phenytoin)
Why is Vitamin B12 required in the diet?
In what foods is it found?
What are the causes for its deficiency?
Required in number of enzymatic reactions and deficiency impacts DNA synthesis.
It is only found in foods of animal origin (meat, milk, eggs).
Deficiency caused by:
- Inadequate Intake
- Inadequate Intrinsic Factor Secretion (required for B12 secretion), due to AI disease against parietal cells/IF or resective surgery. If this occurs will get a pernicious anaemia where parenteral B12 administration would be required
- Inadequate release from food (gastritis, PPIs, Alcoholism)
- Diversion of dietary B12 from desired pathway (bacterial overgrowth, small intestinal anaemia)
- Malabsorption (crohn’s, ileum resection
Outline the clinical features of folate and B12 deficiencies
For both, get Generic anaemia s/s, occasionally mild jaundice, glossitis + oral ulceration.
In addition to these, for B12 also get peripheral neuropathy and demyelination with subacute combined degeneration of spinal cord.
Management of Megaloblastic anaemias (folate/b12 deficiency)
Management of these megaloblastic anaemias should include investigations to identify cause. A blood film, followed by serum folate and B12 testig should be done. When doing serum testing, it is important to take the B12 and Folate sample together, reintroduce it together, and even when giving supplements, give both together, as not doing this can lead to neurological damage (grey are not yet fully understood).
If anaemia is pernicious, require parenteral B12 supplementation to bypass GI system i.e. intramuscular injection
Causes of Normoblastic Anaemia
- Excess Alcohol
- Liver Dysfunction
- Hypothyroidism
- Drugs
Outline the 3 congenital defect types which result in haemolytic anaemias
Membrane Defects- mutation which affects number of proteins essential to maintain cell membrane integrity leads to fragility and haemolytic of them. Hereditary spherocytosis (sphere shaped RBCs) is an example
Enzyme Defects- G6DP Deficiency results in increased sensitivity to oxidative stress
Globin Defects-includes thalassaemias and sickle cell anaemia
Outline the two types of acquired causes of haemolytic anaemias
Cause will either be immune or non-immune.
Immune causes can either be autoimmune (RBCs become coated in IgG and get phag’d by Macphag’) or
Alloimmune cases can occur following transfusion of RBCs triggering an antibody production against them.
Non-immunes causes include mechanical trauma (i.e. metallic valve placement), burns, infections, drugs
