Anaemia Flashcards
What is the definition of anaemia?
Defined as the condition whereby there is a reduction in the number of erythrocytes and haemoglobin within circulation
What are the main cases of anaemia?
Reduced production of erythrocytes/haemoglobin in bone marrow
Reduced survival of erythrocytes in the circulation - haemolysis
Loss of blood from the body
Pooling of erythrocytes within the spleen - splenic sequestration (Splenomegaly)
What are the three main causes for reduced red cell survival?
Hereditary spherocytosis
Autoimmune haemolytic anaemia
G6PD deficiency
What are the three main causes for a reduced red cell production?
Iron deficiency anaemia Anaemia of chronic disease Megaloblastic anaemia (Vitamin B12 deficiency)
What is associated with microcytic anaemia and hypochromia?
characterised with relatively smaller erythrocytes with a larger area of central pallor. (MCHC is low).
Which cells are associated with microcytic anaemia?
Target cells
Elliptocytes
What are the causes of microcytic anaemia?
Iron deficiency
Anaemia of chronic disease
Thalassemia
What is thalassemia?
Impaired beta and alpha chain synthesis
What is normocytic anaemia?
Anaemia with standard sized erythrocytes
What the main causes of normocytic anaemia?
Recent blood loss
Failure of production of red cells - leukaema
Pooling of red cells in the spleen - hyperspenism (liver cirrhosis), splenic sequestration in sickle cell anaemia
What is macrocytic anaemia?
Associated with normochromia, anaemia with comparatively larger erythrocytes.
What are the causes of macrocytic anaemia?
Vitamin B12/Folate deficiency Use of drugs interfering with DNA synthesis Liver disease and ethanol toxicity Haemolytic anaemia (reticulocytes increased)
What is anaemia of chronic disease?
Anaemia of chronic disease is a disease entity in which anaemia occurs on a background of chronic disease (e.g. rheumatoid arthritis). It is thought to occur due to the abundance of pro-inflammatory cytokines (e.g. IL-1 and TNF-alpha) in chronic disease. These cytokines suppress the absorption and transport of iron thereby limiting the ability of the body to use this iron in red cell production. (Hepcidin is elevated)
• Malignancy, rheumatoid arthritis and infections including TB & HIV are common causes.
Which pro-inflammatory cytokines are elevated in anaemia of chronic disease?
IL-1 and TNF-alpha
Which hormone is up-regulated in anaemia of chronic disease?
Hepcidin
Which conditions are implicated in anaemia of chronic disease?
Malignancy, rheumatoid arthritis and infections (TB & HIV)
What are the ferritin levels in iron deficiency anaemia?
Low
Describe the level of transferrin in iron deficiency anaemia?
High
What is hereditary spherocytosis?
An inherited disorder of the red cell membrane which results in spherical red blood cells that have lost their biconcave shape, spherocytes can be identified on blood film.
Why does haemolytic anaemia arise in hereditary sphereocytosis?
Due to the fragile nature of spherocytes (spherical shape is less flexible) - removed and destroyed by the spleen
What symptoms arise due to hereditary sphereocytosis?
Jaundice - hyperbillrubinaemia
Elevated reticulocyte count
Gallstones
Why are reticulocytes elevated in hereditary spherocytosis?
Compensatory mechanism in response to increased rate of red-cell destruction
What is the treatment for hereditary spherocytosis?
Folic acid supplementation (because of increased need)
Splenectomy (if severe), to increase red cell life span
Why is there an increased risk of gallstones in patients with hereditary spherocytosis?
Increased haemolytic breakdown of haemoglobin to bilirubin.
Elevated in conjugated bilirubin indicates obstruction jaundice within the common bile duct (gall stones), since the liver has the capacity to conjugate BR however not adequately being delivered from the bile ducts and gallbladder into the duodenum
What is autoimmune haemolytic anaemia?
Caused by the generation of antibodies that target red cell antigens.
What are the common causes of autoimmune haemolytic anaemia?
lymphoproliferative and autoimmune diseases
N.B: May be idiopathic
What happens to the reticulocyte count in autoimmune haemolytic anaemia?
Elevated
What test is done in patients with autoimmune haemolytic anaemia?
DAT test
Direct anti-globulin test