Paediatric haematology Flashcards
What kind of anaemia can sickle cell disease lead to?
Haemolytic anaemia
How many units makes up heamoglobin?
4
What subunits make up adult haemoglobin?
2 alpha and 2 beta
What subunits make up fetal haemoglobin?
2 alpha and 2 gamma
What does the difference in structure of fetal haemoglobin allow it to do?
Has a higher affinity for oxygen so oxygen binds more easily and releases less easily
What is on the axis of oxygen dissociation curve?
y-axis is saturation of oxygen and x-axis is partial pressure of oxygen
Which is further to the right on the oxygen dissociation curve, adult or fetal and why?
Adult as adult requires higher partial pressure of oxygen for the molecule to fill with oxygen compared to fetal
How much haemoglobin is fetal at birth?
About half
What abnormality causes sickle cells?
A genetic abnormality in the beta subunit coding
Why can you not get sickled fetal haemoglobin?
Because fetal haemoglobin doesn’t have beta subunits
What can be used to increase the production of fetal haemoglobin in patients with sickle cell anaemia?
Hydroxycarbamide
What does hydroxycarbamide protect against?
Sickle cell crises and acute chest syndrome
At what week of gestation does HbF start to decrease?
32-36 weeks
What kind of genetic condition is sickle cell anaemia?
Autosomal recessive
What gene is abnormal in sickle cell disease and where is it?
The gene for beta- globin and it is found on chromosome 11
How does having one copy of the sickle cell gene act as a selective advantage?
Reduces the severity of malaria
How is sickle cell disease diagnosed?
With the newborn screening heel prick test at 5 days of age
What are some complications of sickle cell disease?
Anaemia
Increased risk of infection
Stroke
Avascular necrosis
Pulmonary HTN
Painful and persistent penile erection
CKD
Sickle cell crisis
Acute chest syndrome
What is given as prophylaxis against infection in sickle cell disease?
Penicillin V (phenoxymethypenicillin)
What drug can be used to stimulate production of foetal haemoglobin in people with sickle cell disease?
Hydroxycarbamide
What can sickle cell crisis be triggered by?
infection, dehydration, cold or significant life events
What are the symptoms of vaso-occlusive crisis in sickle cell disease?
Dehydration, raised haematocrit, pain and fever and can cause priopism
What is aplastic crisis in sickle cell disease?
temporary loss pf the creation of new blood cells
What kind of infection most commonly triggers aplastic disease in sickle cell anaemia?
Paravirus B19
What can splenic sequestrian crisis lead to in sickle cell disease?
Severe anaemia and circulatory collapse
What is anaemia?
low level of haemoglobin
What are the causes of haemolytic anaemia in infancy?
Physiologic
Anaemia of prematurity
Blood loss
Haemolysis
Twin-twin transfusion
What are the causes of haemolysis in infancy?
Haemolytic disease of the newborn
Hereditary spherocytosis
G6PD deficiency
When is there a dip in haemoglobin levels naturally and why?
6-9 weeks
High oxygen at birth results in lower haemoglobin production
Who are most likely to become anaemic in infancy?
Premature babies
What are the causes for anaemia in 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 days
Reduced erythropoietin levels
Blood tests remove a significant portion of the circulating powers
What causes haemolysis of the newborn?
incompatibility between rhesus antigens
What are the main symptom of haemolysis of newborn?
Jaundice (high bilirubin) and anaemia
How does rhesus D difference cause haemolysis of the newborn?
A woman who is rhesus D negative may have a rhesus D positive baby. She will produce antibodies to the rhesus D antigen which will attack in a secondary pregnancy
What might causes a rhesus D problem in a first pregnancy?
Antepartum haemorrhage
What is the test for immune haemolytic anaemia?
Direct Coombs test which will be positive in haemolytic disease
What are the common causes of anaemia in older children?
Iron deficiency anaemia and blood loss due to menstruation
What are the rarer causes of anaemia in children?
Sickle cell anaemia
Thalassemia
Leukaemia
Hereditary spherocytosis
Hereditary elliptocytosis
Sideroblastic anaemia
What is helminth infection and what does it cause?
Infection with roundworms, hookworms or whipworms
What is helminth infection treated with?
Albendazole or mebendazole
What are the causes of microcytic anaemia?
TAILS
Thalassemia
Anaemia of chronic disease
Iron deficiency anaemia
Lead poisoning
Sideroblastic anaemia
What are the causes of Normocytic anaemia?
3A + 2H
Acute blood loss
Anaemia of chronic disease
Aplastic anaemia
Haemolytic anaemia
Hypothyroidism
What are the two types of macrocytic anaemia?
Megaloblastic or normoblastic
What is megaloblastic anaemia the result of?
Impaired DNA synthesis preventing the cell from dividing normally; it divides into a large abnormal cell. This is caused by vitamin deficiency.
What is megaloblastic anaemia caused by?
B12 deficiency
Folate deficiency
What is normoblastic macrocytic anaemia caused by?
Alcohol
Reticulocytes
Hypothyroidism
Liver disease
Drugs such as azathioprine
What are the generic symptoms of anaemia?
Tiredness
Shortness of breath
Headaches
Dizziness
Palpitations
Worsening of other conditions
What symptoms are specific to iron deficiency anaemia?
Pica- dietary cravings for abnormal things such as dirt
Hair loss
What are the generic signs of anaemia?
Pale skin
Conjunctival pallor
Tachycardia
Raised respiratory rate
What signs are specific to iron deficiency anaemia?
Koilonychia
Angular cheilitis
Atrophic glossitis
Brittle hair and nails
What sign is specific to haemolytic anaemia?
Jaundice
What sign is specific to thalassemia?
Bone deformities
What are the initial investigations for anaemia?
Full blood count for haemoglobin and MCV
Blood film
Reticulocyte count
Ferritin (low in iron deficiency)
B12 and folate
Bilirubin (raised in haemolysis)
Direct Coombs test
Haemoglobin electrophoresis (for haemaglobinopathies)
What does a high level of reticulocytes in the blood indicate?
active production of red blood cells to replace lost cells- haemolysis or blood loss
What can cause iron stores to be too low?
Dietary insufficiency
loss of iron (heavy menstruation)
Inadequate iron absorption
Where is iron mainly absorbed?
duodenum and jejunum