Anaemia and B12 deficiency Flashcards
What is Autoimmune Hemolytic Anemia (AIHA)?
A condition where the immune system attacks and destroys the body’s own red blood cells.
What are the two types of AIHA?
‘Warm’ and ‘cold’ AIHA, classified based on the temperature at which the antibodies best cause hemolysis.
What is the most common type of AIHA?
Warm AIHA.
At what temperature does haemolysis occur best in Warm AIHA?
At body temperature.
What type of antibody is typically involved in Warm AIHA?
IgG.
Where does haemolysis typically occur in Warm AIHA?
Extravascular sites, such as the spleen.
What are some general features of haemolytic anaemia?
Anaemia, reticulocytosis, low haptoglobin, raised lactate dehydrogenase (LDH), and indirect bilirubin.
What are specific diagnostic features of AIHA?
Positive direct antiglobulin test (Coombs’ test).
What type of antibody is typically involved in Cold AIHA?
IgM.
At what temperature does haemolysis occur best in Cold AIHA?
At 4 degrees Celsius.
How is hemolysis mediated in Cold AIHA?
By complement and is more commonly intravascular.
What are some symptoms associated with Cold AIHA?
Symptoms of Raynaud’s and acrocyanosis.
What are common first-line treatments for Warm AIHA?
Steroids, potentially combined with rituximab.
Why do patients with Cold AIHA respond less well to steroids?
Because the hemolysis is complement-mediated and primarily intravascular.
What is a common autoimmune disease associated with Warm AIHA?
Systemic lupus erythematosus.
What is the significance of the direct antiglobulin test in diagnosing AIHA?
It detects antibodies attached to red blood cells, confirming immune-mediated hemolysis.
What are the main categories of hereditary haemolytic anaemias?
Hereditary haemolytic anaemias can be subdivided into membrane, metabolism, or haemoglobin defects.
What are the types of membrane defects causing hereditary haemolytic anaemia?
Hereditary spherocytosis and elliptocytosis.
What is a common metabolic defect causing hereditary haemolytic anaemia?
G6PD deficiency.
What are haemoglobinopathies?
Disorders like sickle cell disease and thalassaemia that affect the structure or production of haemoglobin.
How can acquired haemolytic anaemias be classified?
Into immune and non-immune causes.
What are the immune causes of acquired haemolytic anaemia?
Autoimmune (warm/cold antibody type), alloimmune (transfusion reaction, haemolytic disease of the newborn), and drug-induced.
What is autoimmune haemolytic anaemia?
An autoimmune disorder where antibodies target own red blood cells, can be warm or cold type.
What are examples of alloimmune haemolytic anaemia?
Transfusion reactions and haemolytic disease of the newborn.
Which drugs can cause immune-mediated haemolytic anaemia?
Methyldopa and penicillin.
What characterizes non-immune causes of acquired haemolytic anaemia?
Characterized as Coombs-negative and includes mechanical, chemical, and infection-related causes.
What are examples of conditions that cause microangiopathic haemolytic anaemia (MAHA)?
Thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), disseminated intravascular coagulation (DIC), malignancy, and pre-eclampsia.
What role do prosthetic heart valves play in haemolytic anaemia?
Can cause mechanical destruction of red blood cells leading to haemolysis.
What is paroxysmal nocturnal haemoglobinuria?
A rare disorder where red blood cells break down at night.
How can infections lead to haemolytic anaemia?
Examples include malaria.
What drug-related cause is associated with non-immune haemolytic anaemia?
Dapsone is associated with causing non-immune haemolytic anaemia.
What is Zieve syndrome?
A rare clinical syndrome of Coombs-negative haemolysis, cholestatic jaundice, and transient hyperlipidaemia associated with heavy alcohol use.
How is Zieve syndrome typically resolved?
Typically resolves with abstinence from alcohol.
What happens in intravascular haemolysis?
Free haemoglobin is released, binds to haptoglobin, and when saturated, binds to albumin forming methaemalbumin.
What does haptoglobin bind to in intravascular haemolysis?
To free haemoglobin. Once saturated, haemoglobin binds to albumin.
What is methaemalbumin and how is it detected?
Methaemalbumin is a complex of haemoglobin and albumin formed when haptoglobin is saturated. It is detected by Schumm’s test.
What are the clinical manifestations of intravascular haemolysis?
Presence of free haemoglobin in the urine (haemoglobinuria) and haemosiderinuria.
What are some causes of intravascular haemolysis?
Mismatched blood transfusion, G6PD deficiency, red cell fragmentation (heart valves, TTP, DIC, HUS), paroxysmal nocturnal haemoglobinuria, cold autoimmune haemolytic anaemia.
How does G6PD deficiency typically cause haemolysis?
While it typically leads to intravascular haemolysis, there is also an element of extravascular haemolysis.
What is extravascular haemolysis?
Occurs when red cells are destroyed primarily in the spleen or liver rather than in the bloodstream.
What are some causes of extravascular haemolysis?
Haemoglobinopathies (sickle cell, thalassaemia), hereditary spherocytosis, haemolytic disease of the newborn, warm autoimmune haemolytic anaemia.
What is iron deficiency anaemia?
A condition characterized by a deficiency of iron, leading to a reduction in red blood cells or haemoglobin.
Who has the highest incidence of iron deficiency anaemia?
Preschool-age children.
What are the main causes of iron deficiency anaemia?
Excessive blood loss, inadequate dietary intake, poor intestinal absorption, increased iron requirements.
What is the most common cause of iron deficiency anaemia in pre-menopausal women?
Blood loss due to menorrhagia.