Quesmed videos (haemolytic anaemia 1+2) Flashcards
What is haemolytic anaemia?
A disorder in which red blood cells are destroyed faster than they can be made.
The destruction of red blood cells is called haemolysis.
What features would indicate haemolytic anaemia?
Examination findings: splenomegaly and jaundiced sclera with pale conjunctiva.
Low haemoglobin
Schistocytes (fragmented RBC’s)
Raised unconjugated bilirubin
What is a feature of a patients past surgical history that would make haemolytic anaemia more likely?
The insertion of a prosthetic heart valve (especially a metal one).
How can prosthetic heart valves cause intravascular haemolytic anaemia?
Since the turbulent blood flow around the mechanical valve causes mechanical damage to the erythrocytes (RBC’s).
Why is unconjugated bilirubin raised in haemolytic anaemia?
Haemoglobin from destroyed erythrocytes (RBC’s) is broken down into globin (which is recycled) and haem.
The haem is further broken down into iron and unconjugated bilirubin.
What type of anaemia does haemolysis cause?
Normocytic anaemia (normal MCV on blood film)
Erythrocytes are normal sized however there is fewer in the blood due to increased destruction.
What are the causes of microcytic anaemia (TAILS)?
Remember: TAILS
Thalassaemia
Anaemia of chronic disease
Iron deficiency anaemia
Lead poisoning
Sideroblastic anaemia
What are the causes of normocytic anaemia (ABCD)?
Remember: ABCD
Acute blood loss
Bone marrow failure
Chronic disease
Destruction of RBC’s (haemolysis)
What are the causes of macrocytic anaemia (FAT RBC)?
Remember: FAT RBC
Foetus (pregnancy)
Alcohol excess
Thyroid
Reticulocytosis (increased immature RBC’s)
B12 and folate deficiency
Cirrhosis or chronic liver disease
What does haemolysis do to reticulocyte count?
Raises the reticulocyte count because the bone marrow is attempting to compensate for the increased destruction of erythrocytes.
What is LDH?
An intracellular enzyme released into the serum when erythrocytes are broken down.
What is haptoglobin?
A glycoprotein which binds to free haemoglobin in the serum and transports it to the reticulo-endothelial system for breakdown.
How is haptoglobin affected in intravascular haemolysis?
In intravascular haemolysis, there are greater amounts of haemoglobin in the serum that bind to haptoglobin.
This is then removed and taken to the reticuloendothelial system resulting in less haptoglobin overall.
What are the 2 main haemolysis types?
Intravascular and extravascular haemolysis
Why is reticulocyte count high in haemolytic anaemia?
Haemolysis triggers the kidneys to produce erythropoietin which triggers the bone marrow to produce reticulocytes.
This is the bodies mechanism for trying to compensate for the decrease in haemoglobin and RBC’s.
What is the most common type of haemolysis?
Extravascular haemolysis
Where does extravascular haemolysis occur?
Reticulo-endothelial system (liver and spleen)
What is the mechanism of extravascular haemolysis?
Macrophages in the liver, spleen, bone marrow and lymph nodes engulf and destroy the erythrocytes in the reticulo-endothelial system.
Typically presents with splenomegaly and hepatomegaly on examination.
As well as high levels of unconjugated bilirubin.
Where does intravascular haemolysis occur?
Within the bloodstream where RBC’s are destroyed within the blood vessels
What is the mechanism of intravascular haemolysis?
Characterised by the rupture or lysis of red blood cells, leading to the release of haemoglobin into the bloodstream.
Haemoglobin released from lysed red blood cells may bind to haptoglobin or be filtered by the kidneys, leading to the presence of haemoglobin in the urine (haemoglobinuria).
What is the classic presentation for haemolytic anaemia?
Fatigue, pallor, SOB and tachycardia.
Jaundice
Splenomegaly
Gallstones
Dark urine - haemoglobinuria (occurs with intravascular haemolysis)
Signs of underlying disorder e.g. malar rash in SLE, may be contributing factor to haemolysis.
What is the cause of jaundice in haemolytic anaemia?
Bilirubin released as a breakdown product of haemoglobin causing raised unconjugated bilirubin.
What is the cause of splenomegaly (and possible hepatomegaly) in haemolytic anaemia?
Enlarged spleen since spleen is being filled with damaged RBC’s
What is the cause of gallstones in haemolytic anaemia?
Increased bilirubin levels
What is the cause of dark urine in haemolytic anaemia?
Caused by haemoglobinuria (occurs with intravascular haemolysis)
What is G6PD deficiency?
Deficiency of Glucose-6-Phosphate Dehydrogenase
Inheritance pattern of G6PD deficiency?
X-linked recessive
Features of G6PD deficiency?
Usually in those with Mediterranean and African ethnicity
Neonatal jaundice
Episodic intravascular haemolysis triggered by oxidative stress
What are the triggers for G6PD deficiency?
Intercurrent illness or infection
Fava beans
Henna
Medications(i.e. nitrofurantoin, colchicine, chloroquine).
What medications can trigger G6PD deficiency?
Dapsone, nitrofurantoin and NSAID’s
What is present in blood film for G6PD deficiency?
Heinz bodies (typically in response to oxidative stress)
Bite cells (erythrocytes with an irregular membrane caused by splenic macrophages attempting to remove Heinz bodies from inside erythrocytes).
Diagnostic test for G6PD deficiency?
G6PD enzyme assay
Treatment for G6PD deficiency?
Avoidance of precipitants, may require transfusions during acute episodes.
What are target cells?
RBC’s showing a target-like appearance on blood film
What are target cells usually an indication of?
Haemoglobinopathies such as thalassemia, where abnormal haemoglobin production affects red blood cell shape.
Liver diseases such as obstructive jaundice or cirrhosis, where altered lipid metabolism affects red blood cell membrane composition.
Iron deficiency anaemia or other conditions causing decreased red blood cell volume, leading to relative excess membrane.
What are burr cells on blood film?
Burr cells, also known as echinocytes, are red blood cells with numerous small, evenly spaced projections on their surface, giving them a spiky or thorny appearance.
What is a condition that may cause burr cell presence?
Disseminated intravascular coagulation (DIC), a disorder characterised by widespread activation of coagulation, leading to microvascular thrombosis and haemolysis.
What are Howell-jolly bodies?
Howell-Jolly bodies are small, round, basophilic inclusions found within red blood cells.
Howell-Jolly bodies are remnants of the cell nucleus that are normally removed from mature red blood cells during their development in the bone marrow.
What could howell jolly bodies indicate?
Splenectomy: Removal of the spleen can lead to Howell-Jolly body formation due to the absence of the spleen’s filtering function.
Megaloblastic anemia: Certain conditions causing impaired DNA synthesis, such as vitamin B12 deficiency or folate deficiency, can result in Howell-Jolly body formation.
Myelodysplastic syndromes or other bone marrow disorders: In some cases, Howell-Jolly bodies may be seen in individuals with abnormalities in bone marrow function.
What are pappenheimer bodies on blood film?
Pappenheimer bodies appear as small, irregular, blue-staining granules within red blood cells when viewed under a microscope.
What does the presence of pappenheimer bodies mean?
The presence of Pappenheimer bodies on a blood film can indicate the accumulation of iron within red blood cells.
This iron accumulation may be a result of various conditions affecting iron metabolism or conditions associated with increased iron uptake or storage.
What conditions do pappenheimer bodies indicate?
Sideroblastic anemia: A group of disorders characterised by impaired haem synthesis, leading to the accumulation of iron within red blood cell precursors (erythroblasts) and mature red blood cells.
Iron overload disorders: Conditions such as hemochromatosis or transfusional iron overload can result in excess iron deposition within red blood cells and other tissues.
