Haemolysis Flashcards
What causes warm autoimmune hemolysis?
(1) IgG autoantibodies
(2) idiopathic
(3) linked to SLE, CLL, drugs, and infections.
(4) Occurs at ≥ 37°C.
Define Haemolysis
hola
Premature red cell destruction, can result in anaemia
What causes cold autoimmune hemolysis?
(1) IgM autoantibodies
(2) linked to infections (EBV, mycoplasma).
(3) Occurs at 0-10°C
(4) can angulate, cause holes in cell (MAC)
What causes alloimmune hemolysis?
The immune system attacks transfused red blood cells
What causes hemolytic transfusion reactions?
(1) Immediate (IgM) intravascular
(2) Delayed (IgG) extravascular
What is the hemolytic disease of the newborn?
Due to Rh or ABO incompatibility, or anti-Kell antibodies
What causes mechanical red cell destruction?
(1) DIC - Disseminated Intravascular Coagulation
(2) HUS - Hemolytic Uremic Syndrome
(3) TTP - Thrombotic Thrombocytopenic Purpura
(4) leaking heart valves
(5) malaria
(6) burns that physically damage red blood cells
What causes hereditary spherocytosis?
A genetic defect causes RBCs to be sphere-shaped instead of biconcave.
= Results in jaundice, and splenomegaly, and can lead to aplastic crises due to parvovirus B19 infection
What is G6PD deficiency?
X-linked condition causing hemolysis triggered by infection, drugs, or fava beans.
More common in Mediterranean/Middle Eastern populations
Why are RBCs particularly susceptible to damage?
Biconcave shape, lack of nucleus, limited metabolic reserve
What is compensated hemolysis?
Increased RBC destruction is matched by increased production, maintaining Hb levels
What is decompensated hemolysis?
RBC destruction exceeds bone marrow production, leading to low Hb levels
What are the consequences of hemolysis?
(1) Reticulocytosis
(2) Erythroid hyperplasia
(3) Excess bilirubin (jaundice, gallstones)
What happens in extravascular hemolysis?
RBCs are destroyed by spleen/liver macrophages
= Leads to jaundice and splenomegaly
What happens in intravascular hemolysis?
RBCs burst in circulation, releasing haemoglobin,
= Leads to hemoglobinemia and hemoglobinuria
What are the clinical features of hemolysis?
jaundice, dark urine (hemoglobinuria), fatigue
What tests confirm hemolysis?
(1) FBC
(2) Reticulocyte count
(3) Unconjugated bilirubin
(4) Blood film (spherocytes, Heinz bodies)
(5) Direct Coombs’ test
What does raised lactate dehydrogenase (LDH) indicate?
It suggests red cell destruction
How is hemolysis treated?
Corticosteroids for autoimmune
IV fluids for transfusion reactions
The first-line treatment for warm autoimmune haemolytic anaemia is what?
steroids
Second-line treatment for hemolysis is what?
Immunosuppressives and splenectomy
If the Coombs test was negative what disease does this rule out and why?
Autoimmune haemolytic anaemia
= Coombs test detects antibodies or complement on the surface of red blood cells. A negative Coombs test indicates that there are no antibodies or complement bound to the red blood cells, which rules out autoimmune hemolysis as the cause of anaemia
If no history of travel was mentioned. What haemolytic disease does this rule out?
Infection induced haemolytic anaemia
A 13-year-old girl of Middle Eastern origin is admitted with jaundice and shortness of breath on exertion. These symptoms have started over the course of the last day. She also complains of dark urine and denies any other symptoms. The patient has a past medical history of gallstones. No drug history or travel history is stated.
On examination, conjunctival pallor and jaundice are noted. She also has henna decorating both of her hands.
The Coomb test was negative. What is the underlying pathology giving rise to this presentation? and why?
G6PD haemolytic anaemia
= Given her ethnic origin and the fact that she has had henna tattooing which can trigger haemolytic crises in patients with G6PD, this is the most likely answer
A 35-year-old man with Glucose-6-phosphate deficiency (G6PD) wants to go on holiday to Nigeria.
What medication should be avoided for malaria prophylaxis?
Primaquine
Heinz bodies and bite cells on the blood film suggest what
oxidative damage to red blood cells, which are common in conditions like G6PD deficiency
The patient’s history of neonatal jaundice may have been an early sign for what?
G6PD deficiency
A 59 year old woman is found to have features of extra-vascular haemolysis on investigation for fatigue; with a haemoglobin concentration of 88 g/L (normal range 115-150 g/L), unconjugated hyperbilirubinaemia of 46 mmol/L (normal <17), and splenomegaly on examination.
The blood count is otherwise normal, and her blood film shows spherocytes and reticulocytosis, and no evidence of intracellular parasites or red cell fragments. There is no social, travel or family history of relevance.
What is the single most appropriate next step?
Coombs’ test (direct antigen test)
A 32-year-old male from northern Europe attends the GP for his annual influenza vaccine and 5-yearly pneumovax booster.
He is new to the practice and informs the GP that he had a splenectomy when he was 4 years old for recurrent haemolytic episodes. He is unable to remember the name of the underlying disease. He also explains that there is a prominent family history of similar issues: his father, and two of his three daughters are affected, but his wife is unaffected.
On examination, the GP notes a splenectomy scar, but no other findings. What is the single most likely underlying diagnosis?
Hereditary spherocytosis
What are the triggers for glucose-6-phosphatase (G6PD) deficiency?
(1) Intercurrent illness or infection
(2) Fava beans
(3) Henna
(4) Medications: primaquine, sulfa-drugs (such as sulfamethoxazole), nitrofurantoin, quinolones, dapsone and NSAIDs/Aspirin
A 70-year-old male presents to the general practitioner complaining of a three-month history of his hands and feet changing colour to dark red. This only happens when he is exposed to cold temperatures and is painful. He also reports a gradual onset of increasing fatigue and breathlessness. His past medical history includes chronic lymphocytic leukaemia. Blood tests show haemoglobin 86 g/l (normal range 135-180g/l), reticulocytes 3.4% (normal range 0.5-1.5%) and a positive Coombs test.
Given the likely diagnosis, which immunoglobulin is most likely involved? and explain why.
IgM
Cold autoimmune haemolytic anaemia, which occurs at temperatures around 0-10 degrees, is caused by IgM autoantibodies
IgG antibodies are seen in warm autoimmune haemolytic anaemia
What are the first line investigation of chronic lymphocytic leukaemia?
Flow cytometry of peripheral blood
A 33-year-old female presents to the GP with fatigue and dyspnoea on exertion. Investigations reveal a normocytic anaemia, reticulocytosis and positive Direct Antiglobulin Test (DAT). Her past medical history includes systemic lupus erythematosus and asthma. She regularly takes beclomethasone 200mcg BD inhaler and the oral contraceptive pill.
What would accurately describe the mechanism of the likely diagnosis?
IgG-mediated extravascular haemolytic disease
= given her history of systemic lupus erythematosus (SLE), warm autoimmune haemolytic anaemia is the most likely diagnosis
What are the causes of warm AIHA?
(1) SLE
(2) Idiopathic
(3) Lymphoproliferative neoplasms (eg. chronic lymphocytic leukaemia and lymphoma)
(4) Drugs (methyldopa)
What are the causes of cold AIHA?
(1) Post-infectious (usually after Mycoplasma or EBV)
(2) Idiopathic
(3) Lymphoproliferative disorders
Describe the difference in treatment for warm and cold AIHA
Warm AIHA is managed with prednisolone or immunosuppression (e.g. AZT) and transfusions if severe
whereas
Cold AIHA treatment is mostly supportive, warmed blood is transfused if required and resistant cases may trial rituximab
Is schistocytes a feature in autoimmune haemolysis?
nope
Symptoms: fatigue, jaundice, and splenomegaly. What haemolytic disease does this suggest?
Hot AIHA
Decreased reticulocyte count in those with Haemolytic anaemia. Is this correct?
No, Haemolytic anaemia leads to increased reticulocyte count
What haemolytic disease are Heinz bodies and bite cells present and seen on blood film?
G6PD deficiency
Haemolytic uraemic syndrome (HUS) often is caused by what?
E. coli 0157
What haemolytic diseases show spherocytes and explain the difference
Hereditary spherocytosis: Negative Coombs test, positive EMA binding test.
AIHA: Positive Coombs test (direct antiglobulin test)
What is the genetic inheritance pattern of hereditary spherocytosis?
Autosomal dominant
What Is Hereditary Haemolytic Anaemia?
Includes conditions like sickle cell disease, thalassemias, and hereditary spherocytosis, often caused by genetic mutations affecting RBC structure or function
(eg, Defect in erythrocyte cell membrane)
Common triggers of DIC include what?
(1) sepsis, trauma, malignancy, and obstetric complications
(2) bleeding, bruising at venepuncture sites, hypotension and tachycardia
What are the typical lab findings in DIC?
(1) Prolonged Prothrombin Time/ Activated Partial Thromboplastin Time
(2) Thrombocytopenia
(3) Low fibrinogen
(4) Elevated D-dimer
What haemolytic disease would you find Schistocytes?
Microangiopathic haemolytic anaemias (MAHA)
(eg)
1. Thrombotic thrombocytopenic purpura (TTP)
2. Haemolytic uraemic syndrome (HUS) 3. Disseminated intravascular coagulation (DIC
Describe the difference between spherocytes and schistocytes
(1) Spherocytes
= Small, round, dense red blood cells with no central pallor; formed due to membrane loss
(eg, in AIHA or hereditary spherocytosis)
(2) Schistocytes
= Irregular, fragmented red blood cells; formed due to mechanical damage
(eg, in MAHA, TTP, or DIC)
What does haemolytic anaemia usually present with? - lab findings
(1) Normocytic
(2) Elevated reticulocyte count
(3) unconjugated hyperbilirubinaemia
(4) Raised LDH
Extravascular haemolysis:
What are the causes?
(1) Sickle cell, thalassaemia
(2) Hereditary spherocytosis
(3) Haemolytic disease of newborn
(4) Warm autoimmune haemolytic anaemia
Intravascular haemolysis:
What are the causes?
(1) Mismatched blood transfusion
(2) G6PD deficiency
(3) Red cell fragmentation: heart valves, TTP, DIC, HUS
(4) Paroxysmal nocturnal haemoglobinuria
(5) Cold autoimmune haemolytic anaemia
