Haematology Flashcards
Adult vs Fetal haemoglobin.
Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin, meaning oxygen preferentially crosses the placenta to perfuse the fetus.
What changes occur to haemoglobin at birth?
From 32 weeks gestation, the production of HbF decreases; HbA production increases.
At the time of birth, HbF:HbA is 1:1.
By 6 months of age, most haemoglobin is HbA.
Causes of anaemia in infancy.
- physiological anaemia
- anaemia of prematurity
- blood loss
- haemolysis
- twin-twin transfusion syndrome
Causes of haemolysis in neonates.
- haemolytic disease of the newborn
- hereditary spherocytosis
- G6PD deficiency
What is physiological anaemia of infancy?
There is a normal dip in haemoglobin around 6-9 weeks of age in healthy term babies.
High oxygen delivery to the tissues caused by high haemoglobin levels at birth cause negative feedback, suppressing the production of erythropoietin by the kidneys.
Subsequently, there is a reduced production of haemoglobin in the bone marrow.
What are the reasons for anaemia of prematurity?
- less time in utero receiving iron from the mother
- red blood cell creation cannot keep up with the rapid growth in the first few weeks
- reduced erythropoietin levels
- blood tests remove a significant portion of circulating volume
Pathophysiology of haemolytic disease of the newborn.
What test is used to check for haemolytic disease of the newborn?
Direct Coombs test (DCT)
Causes of anaemia in older children.
- iron deficiency anaemia
- blood loss
- sickle cell anaemia
- thalassaemia
- leukaemia
- hereditary spherocytosis
- sideroblastic anaemia
Causes of microcytic anaemia.
TAILS:
Thalassaemia
Anaemia of chronic disease
Iron deficiency anaemia
Lead poisoning
Sideroblastic anaemia
Causes of normocytic anaemia.
AHAHA:
Acute blood loss
Haemolytic anaemia
Anaemia of chronic disease
Hypothyroidism
Aplastic anaemia
Causes of macrocytic anaemia.
FAT RBC
Fetus (pregnancy)
Alcohol
Thyroid disease
Reticulocytosis
B12 deficiency
Cirrhosis / chronic liver disease
Symptoms of anaemia.
- tiredness
- shortness of breath
- headaches
- dizziness
- palpitations
- worsening of other conditions
Specific symptoms of anaemia.
Pica - dietary cravings for abnormal things such as dirt can signify iron deficiency.
Hair loss.
Signs of anaemia.
- pale skin
- conjunctival pallor
- tachycardia
- tachypnoea
- koilonychia (?iron deficiency)
- angular chelitis (?iron deficiency)
- glossitis (?iron deficiency)
- brittle hair (?iron deficiency)
- jaundice (?haemolysis)
How should anaemia be initially investigated.
- FBC
- blood film
- reticulocyte count
- ferritin
- B12 and folate
- bilirubin
- DCT
- haemoglobin electrophoresis
Management of anaemia in children.
Establish the underlying cause and directing treatment accordingly.
Iron deficiency can be treated with iron supplementation.
Severe anaemia may require blood transfusions.
Where is iron usually absorbed?
Duodenum and jejunum
Understanding tests for iron deficiency:
a) serum ferritin
b) serum iron
c) total iron binding capacity
a) the form that iron takes when it is deposited and stored in cells, but can be artificially raised in inflammation;
b) serum iron varies significantly throughout the day, therefore isn’t a useful measure alone;
c) a marker for how much transferrin is in the blood, increasing in iron deficiency;
Management of iron deficiency anaemia.
Treat the underlying cause - usually dietary deficiency.
Iron can be supplemented with ferrous sulphate or ferrous fumarate.
Oral iron can cause constipation and black coloured stools; it’s unsuitable where malabsorption is the cause of the anaemia.
What are the most common types of leukaemia to affect children?
- acute lymphoblastic leukaemia
- acute myeloid leukaemia
- chronic myeloid leukaemia
Pathophysiology of leukaemia.
Genetic mutation of one of the precursor cells in the bone marrow leads to excessive production of a single type of white blood cell.
The excessive production of a single type of cell can lead to suppression of the other cell lines, resulting in pancytopenia:
- anaemia
- leukopenia
- thrombocytopenia
Risk factors for leukaemia.
- radiation exposure
- Down’s syndrome
- Kleinfelter syndrome
- Noonan syndrome
Presentation of leukaemia.
- failure to thrive
- night sweats
- unexplained fever
- petechiae
- unexplained bleeding
- generalised lymphadenopathy
- bone or joint pain
- hepatosplenomegaly
Diagnostic workup for leukaemia.
- FBC (?anaemia, leukopenia, thrombocytopenia, raised WBCs)
- blood film (?blast cells)
- bone marrow biopsy
- lymph node biopsy
For staging:
- CXR
- CT
- LP
- genetic analysis and immunophenotyping of abnormal cells
Management of leukaemia.
MDT:
- chemotherapy
- radiotherapy
- bone marrow transplant
- surgery
Complications of chemotherapy.
- failure to treat the leukaemia
- stunted growth and development
- immunodeficiency
- neurotoxicity
- infertility
- secondary malignancy
- cardiotoxicity
Prognosis of leukaemia.
ALL ~80%
Other types of leukaemia are less favourable.
What is idiopathic thrombocytopenic purpura (ITP)?
Type II hypersensitivity reaction caused by the production of antibodies that target and destroy platelets.
This causes a spontaneous thombocytopenia, causing a purpuric rash.
This can happen spontaneously, or it can be triggered by viral infection.
Presentation of ITP.
Presents in children under the age of 10, with onset of symptoms within 48 hours:
- bleeding
- bruising
- petechial or purpuric rash
Diagnostic work up of ITP.
- FBC (?thrombocytopenia)
- blood film (?exclude leukaemia)
Management of ITP.
Usually no treatment is required and patients are monitored until the platelets return to normal - 70% of patients will remit spontaneously within 3 months.
Treatment may be required if the patient is actively bleeding or severe thrombocytopenia:
- prednisolone
- IV immunoglobulins
- blood transfusions
- platelet transfusions
Why is the use of platelet transfusion in ITP limited?
Platelet transfusions only work temporarily because the antibodies against platelets will begin destroying the transfused platelets as soon as they are infused.
Discharge advice following ITP episode.
- avoid contact sports
- avoid IM injections / LPs
- avoid NSAIDs, aspirin
- advice on managing nosebleeds
- seek help after any injury that may cause internal bleeding.
Management of a nosebleed.
First aid measures 10-15 minutes of pressure to the nostrils.
A topical antiseptic such as Naseptin cream may be applied to prevent re-bleeding.
Management of recurrent or prolonged epistaxis.
Admission to hospital and nasal packing or nasal cautery.