Anaemia Flashcards
What are the symptoms of anaemia?
May be assymptomatic.
Very non specific symptoms:
Fatigue/malaise is the most common symptom
Pale pallor Headaches Faintness Dysopnea Tachycardia
How is anaemia classified and describe the different causes of anaemia?
By MCV: microcytic, normocytic and macrocytic.
Microcytic causes:
Iron deficiency.
Thallasemias
Hereditary sideroblastic anaemia, (the bone marrow is unable to incorporate iron into RBCs properly.)
Normocytic causes:
Anaemia of chronic disease
Renal failure (reduced erythpoeitin aka reduced production)
Acute blood loss ( not enough time to compensate with reticulocytes)
Haematological malignancies
Macrocytic causes: Folate deficiency B9 B12 deficiency Haemolytic causes (G6DP deficiency) Alcoholism
Describe the general physiology of RBC production and the general pathophysiology of anaemia?
EPO released from the mesangial cells from the kidneys.
Stimulates erythropoesis in the bone marrow.
Forms reticulocytes partially nucleated which develop into erythrocytes.
After approximately 120 days they get destroyed in the reticular endothelial system (RES) in the spleen.
RES works like a filter if the RBC is too large, or old it gets broken down by macrophages, therefore if RBC which are incorrectly formed may be broken down more quickly.
Anaemia in general terms is due to:
An underproduction of RBC or an over destruction of RBC
What are the common causes of iron deficiency anaemia?
Worldwide: Hook worm is the most common cause of iron deficiency anaemia and all anaemia. But it is rare in the western world.
General causes:
Bleeding (GI bleed: peptic ulcers, colorectal ca, polyps, diverticuli. Menustration. Hook worm.)
Demand > Supply (growth, pregnancy, reduced intake)
Malabsorption potentially following a gastrectomy (rare)
Discuss the investigations used to confirm a patient has iron deficiency anaemia?
FBC: Microcytic anaemia
Blood film + iron studies:
Low serum ferritin
Transferrin also reported as TIBC (Total Iron Binding Capacity) will be raised as the liver makes more transferrin to try and compensate.
Outline the appropriate investigations for a patient with confirmed iron deficiency anaemia?
Any anaemia always check previous results.
If bleeding is suspected enquire about menustration and consider endoscopy.
Give oral iron and see if the Hb normalises
Outline the physiological absorption of B12 and Folate and the area of the bowel in which it occurs?
B12 needs intrinsic factor released from the parietal cells to be absorbed.
B12 is absorbed in the terminal ileum therefore there is often B12 deficiency anaemia in patients with ileal resections.
Folate is found in leafy greens and is absorbed in the jejenum. Alcoholics with a poor dietary intake are often deficient.
Describe the pathophysiology and diagnosis of B12 or folate deficiency anaemia?
Folate is needed in DNA purine production (adenosisne and guanine) and B12 is needed to activate the folate.
When there is deficiency in either this causes the RBC to grow too much giving it a macrocytic appearance this then causes increased destruction of these RBC’s by the RES.
What is sickle cell anaemia?
It is a autosomal recessive disease which causes RBC’s to be sickle shaped and have a reduced life span.
The reduced life span is exacerbated by low oxygen tension, dehydration and the cold.
What are the clinical features of sickle cell anaemia?
In the most severe form HbSS:
Anaemia of ~6 there will be malaise and potential breathlessness associated.
May be haemolytic jaundice. Note may have splenomegaly in young children.
Increase incidence of infection (pneumococcal) due to hyposplenism due to infarcts (sickle celled rbc more likely to occlude vasculature)
Painful crises due vaso-occlusive episodes often in the hand and feet. Often accompanied by a haemolytic crisis as sickle cells have a reduced life span during crises.
Priapism
How is sickle cell anaemia diagnosed?
Usually diagnosed via the guthrie test performed in the neonatal period. This involves screening for the HbS.
Haemoglobin electrophoresis is then used to differentiate between patients that are homo/heterozygous for HbS.
How is sickle cell anaemia managed including painful crises?
Full immunisation.
Prophylactic daily oral penicillin throughout childhood.
Folic Acid supplementation.
Vaso-occlusive crises should be avoided by avoiding the:
- cold
- dehydration
- exercising excessively
- undue stress
- hypoxia.
Treatment of an acute crises should be analgesia, good hydration, oxygen and antibiotics.
Note: Hb should be treated with transfusion when less than 6.
Note 2: Parovirus B19 can cause a 2-3 day halt in BM erythropoesis causing a aplastic crisis treated by transfusion.
What is thallassaemia?
Thalassemia is an autosomal recessively inherited haemaglobinopathy.
There are 2 forms beta and alpha.
Describe the pathophysiology of alpha and beta thallassaemia?
Alpha thalassaemia:
Healthy individuals have 4 alpha global genes. If all 4 are deleted then the individual will not be able to produce alpha global chains. This is known as alpha thalassaemia major which is not compatible with human life.
If there are 3 deletions and 1 functioning gene then the anaemia will be mild-moderate.
If there are 1 or 2 deletions the individual will be an asymptomatic carrier.
In B-thalassaemia due to abnormal genes the body cannot produce adequate amounts of B-globin chains, there is therefore a reduction in HbA (2 alpha and 2 beta).
All affected individuals have a severe reduction in B-globin and disease severity depends on the amount of residual HbA and HbF production.
What are the clinical features of beta thallasaemia?
Profound anaemia with associated symptoms.
Stunted growth.
Haemolytic anaemia
Hepatosplenomegaly and bone marrow expansion (if not treated)
Severity is dependent on residual HbA and HbF production.
