Haemolytic Anaemia Flashcards
what is the definition of haemolytic anaemia?
Reduction in red cell lifespan due to increased red blood cell destruction. Decompensated haemolysis – rate of destruction exceeds rate of synthesis, causing anaemia. Normocytic or macrocytic RBCs. The premature breakdown of RBCs, BEFORE their normal lifespan of around 120 days
what is the epidemiology haemolytic anaemia?
Represents approximately 5% of all anaemias. Acute AIHA is relatively rare, with an incidence of one to three cases per 100,000 population per year
what is the aetiology of haemolytic anaemia?
Red cell membrane disorders (hereditary spherocytosis)
abnormal haemoglobins (sickle cell, B and A thalassaemia)
microangiopathic haemolytic anaemias
prosthetic heart valves
autoimmune haemolytic anaemias
Enzyme defects - G6PD deficiency
what are the risk factors of haemolytic anaemia?
Certain medicine
Infections such as: Viral infections, including mononucleosis. Atypical pneumonia
Certain cancers: Leukemia
Collagen-vascular (autoimmune) diseases, such as systemic lupus erythematosus
Family history of hemolytic disease
what is the pathophysiology of haemolytic anaemia?
The premature breakdown of RBCs, BEFORE their normal lifespan of around 120days
This occurs in:
- The circulation (intravascular):
• When RBCs are rapidly destroyed in circulation, haemoglobin is liberated
• This is initially bound to HAPTOGLOBULIN but these soon become saturated
• Excess free plasma haemoglobin is filtered by the renal glomerulus and enters the urine, although small amounts are reabsorbed by the renal tubules
• In renal tubular cells, haemoglobin is broken down and becomes deposited in the cells as HAEMOSIDERIN
- The reticuloendothelial system i.e. by macrophages of the liver, spleen (in particular) and bone marrow (extravascular)
Consequences of haemolysis:
- Shortening of red cell survival does not always result in anaemia, as there is a compensatory increase in red cell production by the bone marrow
- If the red cell loss can be contained within the marrow’s capacity for increased output, then a haemolytic state can exist with anaemia - known as Compensated haemolytic diseases
- The bone marrow can increase its output by 6-8 times by increasing the proportion of cells committed to erythropoiesis (RBC production) (erythroid hyperplasia) and by expanding the volume of active marrow
- Additionally, reticulocytes (immature RBCs) are released PREMATURELY
- These cells are LARGER than mature cells, hence MACROCYTIC, and stain with a light blue tinge on a peripheral blood film (polychromasia)
what are the key presentations of haemolytic anaemia?
acute anaemia, jaundice, haematuria, dyspnea, fatigue, tachycardia, and possibly hypotension
what are the signs fo haemolytic anaemia?
Jaundice, hematuria, tachycardia, hypotension
what are the symptoms of haemolytic anaemia?
Anaemia symptoms - fatigue, shortness of breath, angina, dyspnea
what are the first line investigations for haemolytic anaemia?
FBC and blood film (spherocytes, polychromasia, red cell fragments)
- High serum UNCONJUGATED BILIRUBIN
- High urinary UROBILINOGEN
- High faecal STERCOBILINOGEN
what are the gold standard investigations for haemolytic anaemaia?
- Splenomegaly
- Bone marrow expansion
- Reticulocytosis - increased reticulocytes
lactate dehydrogenase,
haptoglobin,
direct antiglobulin test (to check for autoimmune causes).
what are the differential diagnoses for haemolytic anaemia?
Infection: Malaria, Babesia, Bartonella, Clostridia, Rickettsia, Haemophilus influenzae
how is haemolytic anaemia managed?
Blood transfusions, medicines (glucocorticoids), plasmapheresis, surgery, blood and marrow stem cell transplants, and lifestyle changes. People who have mild haemolytic anaemia may not need treatment, as long as the condition doesn’t worsen
how is haemolytic anaemia monitored?
haemoglobin level, reticulocyte count, indirect bilirubin value, LDH level, and haptoglobin value in patients with haemolytic anaemia to determine the response to therapy
what are the complications of haemolytic anaemia?
Severe haemolytic anaemia that is not treated or controlled can lead to serious complications, such as arrhythmias; cardiomyopathy, or heart failure
what is the prognosis of haemolytic anaemia?
Overall, mortality rates are low in haemolytic anaemias. However, the risk is greater in older patients and patients with cardiovascular impairment.
