Haematology Flashcards
What is anaemia?
When there is a decrease in haemoglobin.
What two things cause low haemoglobin levels?
Reduction in cell mass
Increased plasma volume
What element is key for making Hb?
Iron
What is the normal mean cell volume?
80-100 femtolitres
What are the 3 main subtypes of anaemia?
Microcytic- low MCV indicating small sized RBC
Normocytic- normal MCV indicating normal sized RBC
Macrocytic- high MCV indicating large sized RBC
What are the 5 causes of microcytic anaemia?
T- Thalassaemia
A- Anaemia of chronic disease
I- Iron deficiency
L- Lead poisoning
S- Sideroblastic anaemia
TAILS
What are 5 causes of normocytic anaemia?
A- anaemia of chronic disease
A- Acute blood loss
A- Aplastic
H- haemolytic
H- Hypothyroidism
3 As and 2 Hs
What are the two subtypes of macrocytic anaemia?
Megaloblastic
Normoblastic
What is megaloblastic anaemia and what causes it?
Problem in DNA synthesis caused by vitamin deficiency
Folate
B12
What causes normoblastic anaemia?
Alcohol
Hypothyroidism
Liver disease
Drugs such as azathioprine
What are the generic signs of anaemia?
Pale skin
Conjunctivital pallor
Tachycardia
Raised respiratory rate
How common is iron deficiency anaemia?
Most common cause in the world
What can cause iron deficiency anaemia?
Vegetarian diet
H. pylori infection
Pregnancy and breastfeeding
IBS
Coeliac
PPI’s
Increased iron loss through bleeding (this is the principal cause if Fe deficiency)
Why does iron loss cause microcytic anaemia?
Iron is needed for the formation of haemoglobin and when there is a lack of iron not enough haemoglobin is made to make normal sized RBC’s.
Therefore smaller RBC’s are produced by the bone marrow which can’t carry enough oxygen to meet the bodies demand hence hypoxia
Where is Iron mainly absorbed in the body?
Duodenum and jejunum
Why are women more prone than men to iron deficiency?
Women lose about 2mg daily when menstruating where as men will only on average lose 1mg a day
How can pregnancy cause anaemia?
Pregnancy results in net loss of 580mg of iron, due to expansion of RBC mass and growth of the foetus and placenta. Most occurs in the third trimester
Why does H.Pylori cause iron deficiency?
It traps Fe itself in the stomach preventing it from reaching the duodenum
How do PPI’s cause iron deficiency?
Iron requires acid from the stomach to stay in it’s soluble form fe2+ where as without acid it becomes insoluble Fe3+. Therefore PPI’s as they reduce amount of stomach acid can lead to Fe deficiency
Why can hair and nails be affected by Iron deficiency?
As iron is required for enzymes in the mitochondria, and as hair and nails are fast growing they are most affected by this deficit
What are the signs of Iron deficiency?
- Conjunctivital pallor
- Koilonychia (spoon shaped nails)
- Angular stomatitis (redness around mouth)
- Glossitis
What are the symptoms of iron deficiency?
- Fatigue
-Dyspnoea on exertion - Dizziness
- Headache
- Nausea
- bowel disturbance
- Hair loss
What investigations would you perform for a patient with suspected iron deficiency?
FBC- would have low Hb, low MCV
- Iron studies would measure the: serum iron, serum ferritin and total iron binding capacity
If ferritin in the blood is low it is highly suggestive of iron deficiency. If ferritin is high then this is difficult to interpret and is likely to be related to inflammation rather than iron overload. A patient with a normal ferritin can still have iron deficiency anaemia, particularly if they have reasons to have a raised ferritin such as infection.
transferrin levels increase in iron deficiency and decrease in iron overload.
How would you treat iron deficiency?
- Treat underlying cause
- Oral iron supplements ferrous sulphate/fumarate
- Iron infusion e.g., cosmofer
- Blood transfusion in severe cases
What are the complications associated with iron deficiency?
- Cognitive impairment
- Impaired muscular performance
- Preterm delivery
- High output heart failure
What is Thalassaemia?
Thalassaemia is an autosomal recessive haemoglobinopathy which causes a microcytic anaemia.
What is alpha thalassemia (AT)?
A genetic disorder where there is a deficiency in the production if the alpha chains of Hb. Autosomal recessive
Where is AT most common?
Asia and Africa
What chromosome is the gene affected in AT found on?
2 on each 16
What are the 4 types of AT?
- Silent carrier- 1 gene deletion
- AT trait- 2 gene deletions. mildly anaemic
- Haemoglobin H disease (HBH)- 3 gene deletions moderate to severe disease
- Haemoglobin barts (HBB) - 4 gene deletions they will die in utero
How does HBH cause problems?
Unable to form alpha chains which means beta chains for tetramers which damages RBC
HBH causes haemolysis as well as having a higher affinity for oxygen so oxygen not released at tissues
How does HBB cause problems?
- Gamma chains form tetramers (Hb Barts), which cannot carry oxygen efficiently
- Severe hypoxia leads to high-output cardiac failure and massive hepatosplenomegaly, resulting in oedema all over the body, called hydrops fetalis.
A consequence of hypoxia is that it signals thebone marrow, as well as extramedullary tissues like the liver andspleen, to increase production of RBCs.
This may causebones containing bone marrow, as well as the liver andspleen, to enlarge.
What are the key presentations of AT?
- Family history
- Risk factors
- Symptoms of anaemia
- Splenomegaly due to destruction of RBC
What are the symptoms of AT?
- Shortness of breath
- Palpitations
- fatigue
- Swollen abdomen
What investigations would you perform for AT?
FBC- measure MCV would show microcytic anaemia
Blood film- microcytic, hypochromic erythrocytes, as well as target cells (look like bullseyes due to scrunching up of the cell membrane) and nucleated RBCs (Howell-Jolly bodies). With moderate alpha thalassaemia, there may begolf-ball like RBCs, due toprecipitatedHbH molecules.
What is the diagnostic test for AT?
Hbelectrophoresis: this is diagnostic. The pattern depends on the type of thalassaemia. HbH (beta chain tetramers) would be present in alpha thalassaemia
What would the treatment for AT trait and silent carrier AT?
Iron supplement if required
What would the treatment for HBH AT be?
- Folic acid supplementation (first line)
- Iron chelation to prevent overload
- Splenectomy
- RBC transfusion
- Then a bone marrow transplant can be curative
What are the complications of AT?
- Heart failure: severe anaemia can lead to high output cardiac failure
- Hypersplenism:compensatory extramedullary hematopoiesis takes place in the spleen leading to splenomegaly and hypersplenism. This, in turn, can cause pancytopaenia
- Aplastic crisis: associated with parvovirus B19 infection and can result in pancytopaenia with reduced reticulocytes
- Iron overload due to regular transfusions:excess iron leads to secondary haemochromatosis which can affect the liver, heart, pancreas, skin, and joints
What is beta thalassaemia?
Beta thalassaemia is a genetic disorder where there’s a deficiency in the production of the β-globin chains of haemoglobin.
It is an autosomal recessive condition.
Where are the beta chains coded for (which chromosome)?
11
What are three types of BT?
BT trait- often asymptomatic
BT intermedia- variable presentation
BT major- will be severe
What is BT trait/minor?
Patients with beta thalassaemia minor are carriers of an abnormally functioning beta globin gene. They have one abnormal and one normal gene.
Thalassaemia minor causes a mild microcytic anaemia and usually patients only require monitoring and no active treatment.
What is BT intermedia?
Patients who have two abnormal copies of the beta-globin gene. Two defective genes or one defective and one deletion.
This will cause more significant anaemia
What is BT major?
Have tow deletions of the beta-globin gene. They have no functioning beta globin genes
Will cause severe anaemia
What happens to a patient with BT major?
- When there’s a β-globin chain deficiency, free α-chains accumulate within red blood cells, and they clump together which damage the red blood cell’s , causing haemolysis
- This causes an excess of unconjugated bilirubin leads to jaundice, and excess iron deposits leads to secondary hemochromatosis.
- The haemolysis can also lead to hypoxia.
- A consequence of hypoxia is that it signals the bone marrow, and extramedullary tissues like the liver and spleen, to increase red blood cell production, which may cause bone marrow containing bones, like those in the skull and face, as well as the liver and spleen, to enlarge.
What are the signs of BT major/intermedia?
- Onset after 2 years of age as no longer gamma chains
- Jaundice (excess bilirubin)
- Pallor
- Splenomegaly
- Chipmunk face enlarged forehead and cheekbones
- Failure to survive
What are the symptoms of BT major?
- SOB
- Palpitations
- Fatigue
- Swollen abdomen
- Growth retardation
What are the first line investigations for BT?
- 1st line
- FBC: microcytic anaemia with more RBC’s as bone marrow compensates in Beta
- Lab work may also show high serum iron, high ferritin, and a high transferrin saturation level.
-
Bloodfilm: microcytic, hypochromic erythrocytes, as well as target cells (look like bullseyes due to scrunching up of cell membrane) and nucleated RBCs (Howell-Jolly bodies)
-
What is the diagnostic test for BT?
Hbelectrophoresis: this isdiagnostic. Reduced HbA and elevated HbA2would be expected inbeta thalassaemia
What other tests might you do for BT?
Skull x-ray- hair-on-end appearance due to marrow hyperplasia
- DNA testing
What are the complications of BT?
Same as AT. These include iron overload, high output heart failure, gallstones, aplastic crisis, hypersplenism
How would you manage BT?
Blood transfusions, folate supplementation, iron chelation, splenectomy, and bone marrow transplant
What is sideroblastic anaemia?
When there is ineffective Erythropoiesis leading to increased iron absorption and loading in the marrow. Will not respond to iron think this when anaemia doesn’t respond to iron.
What is sickle cell anaemia?
Sickle cell anaemia is caused by an autosomal-recessive single gene defect in the beta chain of haemoglobin, which results in production of sickle cell haemoglobin (HbS).
Where is sickle cell most prevalent?
highest prevalence in sub-Saharan Africa s it is protective against malaria
What are the risk factors for sickle cell?
- African: 8% of black people carry the sickle cell gene
- Family history: autosomal recessive pattern
- Triggers of sickling: dehydration, acidosis, infection, and hypoxia
What causes sickle cell anaemia?
Sickle cell anaemia is an autosomal recessive condition where there is an abnormal gene for beta-globin on chromosome 11. One copy results in sickle cell trait and 2 result in sickle cell disease
Describe how sickling occurs?
- Unusual haemoglobin proteins HbS are formed these can carry oxygen perfectly well
- However HbS molecules change it’s shape to allow it to aggregate with other proteins and form long polymers that are crescent in shape this process is called sickling
What can trigger sickling?
Dehydration
Acidosis
Infection
Hypoxia
What are the problems with sickle shaped RBC’s?
- Repeated sickling of RBC’s can damage their cell membranes leading to haemolysis which can cause anaemia can lead to splenomegaly
- To counteract haemolysis increased formation of RBC’s lead to bone enlargement
- In sickled form RBC’s can get stuck in capillaries and cause vaso-occulsion
What are the chronic symptoms of sickle cell anaemia?
- Pain
- Anaemia related symptoms
- Haemolysis leading to jaundice and gallstones
What is a sickle cell crisis and what different ones are there?
Sickle cell crisis is an umbrella term for a spectrum of acute crises related to the condition.
- Sequestration crisis
- Aplastic crisis
- Haemolytic crisis
- Vaso-occlusive crisis
- Acute chest syndrome
What is a sequestration crisis?
- RBCs sickle in the spleen causing pooling of blood this can lead to severe anaemia and circulatory collapse (hypovolemic shock)
- Support with blood transfusions and fluids for shock
- Abdominal pain and splenomegaly will also occur as symptoms
- Can lead to infarction of the spleen if repeated
What is an aplastic crisis?
- Infection caused by parvovirus B19 causes bone marrow suppression
- It leads to significant anaemia. Management is supportive with blood transfusions if necessary. It usually resolves spontaneously within a week.
What is a Vaso-occlusive Crisis (AKA painful crisis)
Vaso-occlusive crisis is caused by the sickle shaped blood cells clogging capillaries causing distal ischaemia.
It is associated with dehydration and raised haematocrit. Symptoms are typically pain, fever and those of the triggering infection. Also priapism in men
What two features are associated with a Vaso-occlusive crisis ?
Dehydration and raised haematocrit.
What is priapism?
Trapping of blood in the penis causing a painful and persistent erection. This is a urological emergency and is treated with aspiration of blood from the penis.
What is a Haemolytic crisis?
- When there is an increased rate of haemolysis
What are the investigations for anaemia?
- New born screening with heel prick happens at day 5
- FBC:normocytic anaemia with reticulocytotic
- Blood film:sickled RBCs, target cells, Howell-Jolly bodies (RBC nuclear remnants seen later in the disease due to hyposplenism)
- Hb electrophoresis and solubility: diagnosticinvestigation, demonstrating**increased HbS (2 alpha chains and 2 abnormal beta chains) and reduced/absent HbA (α2β2)
What is the treatment for sickle cell crises?
- Have a low threshold for admission to hospital
- Treat any infection
- Keep warm
- Keep well hydrated (IV fluids may be required)
- Simple analgesia such as paracetamol and ibuprofen
- Penile aspiration in priapism
What is the long term management for sickle cell anaemia?
- Avoid dehydration and other triggers
- Ensure up to date vaccines
- Antibiotic prophylaxis to protect against infection (phenoxymethylpenicillin)
- Hydroxycarbamide will stimulate the production of foetal haemoglobin which prevents sickle cell crisis
- Blood transfusion
- Bone marrow transplant
What is hydroxycarbamide used for?
Will stimulate the production of foetal haemoglobin which prevents sickle cell crisis and can also be used for beta thalassemia
What is the prognosis for sickle cell anaemia?
Prognosis is variable. The median age at death is 40-50 for patients with sickle cell disease, with a third of patients dying during an acute crisis
What is aplastic anaemia?
A stem cell disorder. It is characterised by anaemia, leukopenia and thrombocytopenia
What causes aplastic anaemia?
- Idiopathic
- radiation and toxins
- Drugs
- Infections HIV
What causes aplastic anaemia?
- The most common cause of aplastic anaemia is autoimmune destruction of haematopoietic stem cells.
- Research shows that there are alterations in the immunologic appearance of haematopoietic stem cells because of genetic disorders, or after exposure to environmental agents, like radiation or toxins.
What are the signs of Aplastic anaemia?
Pallor
What are the symptoms of aplastic anaemia?
- Fatigue
- Palpitations
- Dizziness
- Headaches
- Chest pain and shortness of breath: as heart works harder to compensate for low RBC count
- Increased bleeding and petechiae: due to thrombocytopenia
- Recurrent infections: due to leukopenia
What investigations would you run for aplastic anaemia?
- FBC would should leukopenia, thrombocytopenia and low reticulocyte count
- increased erythropoietin
- Increased bleeding time
- Bone marrow biopsy
What is the treatment for aplastic anaemia?
- Removal/ treatment of causes e.g. drugs or infections
- Transfusions
- Stem cell transplant
- Immunosuppressive treatment
What is G6PD deficiency?
G6PD deficiency is a condition where there is a defect in the G6PD enzyme normally found in all cells in the body.
What is G6PD deficiency?
G6PD deficiency is a condition where there is a defect in the G6PD enzyme normally found in all cells in the body. Makes people more susceptible to haemolytic anaemia
What is the epidemiology of G6PD?
- It is inherited in an X linked recessive pattern, meaning it usually affects males.
- It is more common in Mediterranean, Middle Eastern and African patients.
- 6DPD deficiency can be protective against malaria
Explain the pathophysiology of G6PD?
- G6PD is an enzyme that helps to produce NADPH in the RBCs to protect them from damage by free radicals. The G6PD mutations cause defective G6PD enzymes to be produced that have a shorter half-life.
- Normal red cells can increase generation of NADPH in response to oxidative stress; this capacity is impaired in patients with G6PD deficiency. Failure to withstand oxidative stress damages haemoglobin and the red cell membrane and causes haemolysis.
What are the triggers for anaemia in someone with G6PD deficiency?
- Stress
- Infections
- Acidosis
- Fava beans and soy products
- Red wine
- Medications e.g., Chloroquine
What are the signs of G6PD?
- Jaundice
- Pallor
- Splenomegaly
- Dark tea coloured urine
Symptoms are anaemia, SOB, tiredness dizziness, headaches, palpitations
What are the investigations for G6PD?
- FBC: low levels of RBC, high reticulocytes
- LDH: elevated
- Bilirubin: elevated
- Haptoglobin: low
- Coomb’s test: negative (used to detect immune mediated anaemias)
- Diagnosis can be made by doing aG6PD enzyme assay
What would a blood film of G6PD show?
- Blood film: Heinz bodies and bite cells
What is B12 deficiency anaemia?
Anaemia caused by B12 deficiency it is a macrocytic megaloblastic anaemia
What causes B12 deficiency?
- Inadequate intake (vegans and vegetarians as it is found in animal products)
- Inadequate secretion of intrinsic factor
- Malabsorption (crohn’s, patients who have had a gastric bypass)
- Inadequate release of B12 from food (alcohol abuse and gastritis)
- Can also be caused by pernicious anaemia which is where there is autoimmune destruction of the gastric epithelium
Why does B12 deficiency affect RBCs?
- It is a essential vitamin in DNA synthesis so it will affect rapidly dividing cells e.g., RBC’s and tongue causing glossitis.
What are the signs of B12 deficiency?
- Pallor
- Signs of neurological defect
What are the symptoms of B12 deficiency?
- SOB
- Palpitations
- Headaches
- Fatigue
- Glossitis
- CNS involvement - Personality change
- Depression
- Memory loss
- Visual disturbances
- Numbness, weakness and paraesthesia affecting the lower extremities
- Ataxia
- Loss of vibration sense or proprioception
- Autonomic dysfunction (e.g. bladder/bowel dysfunction)
What would the first line investigations for B12 deficiency be?
– Full blood count (FBC): raised MCV
- Blood film: megaloblastic anaemia +/- hypersegmented neutrophils
- Haematinics: look for iron, B12, folate deficiency
- Lactate dehydrogenase (LDH): may be elevated
- Liver function tests (LFTs)