Haematology Flashcards
What are the types of causes of anaemia in children?
reduced rbc production
increased haemolysis
blood loss
Give examples of causes of reduced rbc production
ineffective erythropoiesis: - iron deficiency - B12/folate deficiency - JIA - chronic renal failure - lead poisoning rbc aplasia: - parvovirus b19 - diamond blackfan - transient erythroblastopenia of childhood
Give examples of causes of increased rbc haemolysis
haemolytic disease of the newborn autoimune haemolytic anaemia haemoglobinopathies: thalassaemia, sickle cell rbc enzyme - G6PD deficiency roc membrane - spherocytosis
What can cause blood loss leading to anaemia?
meckels diverticulum
VW disease
what are causes of iron deficiency anaemia?
inadequate intake
malabsorption
blood loss
what are the clinical features of iron deficiency anaemia?
asymptomatic until <6-7g/dl tire easily slower feeding pica pale?
What are diagnostic clues of iron deficiency anaemia?
low MCV and MCH - microcytic, hypochromic
low serum ferritin
give causes of microcytic anaemia
- Iron deficiency
- Beta-thalassaemia trait
- Alpha thalassaemia
- Anaemia of chronic disease
What is the management of iron deficiency anaemia?
- Change diet
- Oral iron supplements - Sytron (sodium iron edetate), Niferex
Continue supplementation until Hb is normal and then for a minimum of 3 months
why should children w iron deficiency w normal hb still be treated?
iron is essential for normal brain development and IDA is associated w behavioural and intellectual deficiencies
What are the 3 main causes of red cell aplasia?
congenital red cell hyperplasia
transient erythroblastopenia of childhood
parvovirus b19
What are the diagnostic clues of red cell aplasia
low reticulocyte count despite low hb
normal bilirubin
negative direct Coombs
absent red cell precursors on bone marrow examination
what are some congenital abnormalities found in diamond blackfan anaemia?
short stature
abnormal thumbs
What is the rx of diamond blackfan anaemia?
oral steroids
monthly rbc transfusions if steroid unresponsive
What is the difference between diamond blackfan and transient erythroblastopenia of childhood?
same haematological features but TEC always recovers
What are the effects of haemolytic from increased roc breakdown?
anaemia
hepatosplenomegaly
increased blood levels of unconjugated bilirubin
XS urinary urobilinogen
What are the diagnostic clues of haemolytic anaemia?
o Reticulocyte count (lilac on blood film)
o Unconjugated bilirubinaemia (present in the blood) and urinary urobilinogen
o Abnormal appearance of rbc’s on blood film e.g. Sickle cell, spherocytes, v hypochromic)
o +ve coombs
o rbc precursors in the bone marrow
wat is the genetic inheritance of hereditary spherocytosis?
autosomal dominant
how does spherocytosis lead to haemolysis?>
reduction in surface to volume ratio causes them to become spheroidal, they’re less deformable than normal rbc’s and are destroyed in the microvasculature of the spleen
what are the clinical features of hereditary spherocytosis?
Highly variable
Can be asymptomatic
i. Jaundice
ii. Anaemia
iii. Splenomegaly - depending on rate of haemolysis
iv. Aplastic crisis - caused by parvovirus B19 infection
v. Gallstones - due to bilirubin excretion
how is a diagnosis of hereditary spherocytosis made?
blood film- spherocytes
direct ab test if no FH of HS
what is the management of mild spherocytosis
oral folic acid
what is the management of severe spherocytosis?
splenectomy if poor growth and severe signs for >7y.o due to risk of sepsis
what is the management of aplastic crises?
½ blood transfusions over 3-4 weeks when no rbcs are produced
what is the inheritance of G6PD deficiency?
x-linked
what is G6-PD
GLUCOSE 6 phosphate dehydrogenase
rate limiting enzyme
prevents oxidative damage to rbcs
What are the clinical features of G6PD deficiency?
neonatal jaundice (first 3 days of life)
fever
malaise
passage of dark urine (as contains Hb and urobilinogen)
what precipitates acute haemolytic in G6PD deficiency?
infection
drugs
broad beans
why can G6PD b difficult to diagnosis?
between episodes the person has a normal blood picture and no jaundice or anaemia
what is the management of G6PD deficiency ?
make aware of signs of acute haemolytic (jaundice, pallor, dark urine)
avoid certain drugs:
1. antimalarial - primaquine, quinine, chloroquine
2. abs - sulphonamides, quinolone, nitrofurantoin
3. aspirin
What are the different types of haemoglobinopathies that are associated with haemolytic anaemia?
- Sickle cell disease
- HbSC disease
- Sickle cell trait
- and ß-thalassaemia
when do clinical manifestations of haemoglobinopathies appear and why?
around 6 months as most f the HbF present at birth has been replaced by adult HbA
What is a trigger of spherocytosis that can cause transient severe anaemia?
parvovirus b19
what is the pathophysiology in sickle cell disease?
HbS polymerises w/in rbc’s forming rigid tubular spiral bodies -> sickle shape
They have reduced life span and may be trapped in microcirculation causing vast-occlusion and ischaemia in an organ or bone
What exacerbates sx of sickle cell disease?E
low oxygen tension
dehydration
cold
what is the most severe form of sickle cell anaemia?
HbSS
Why are infections more common in sickle cell anaemia?
hyposplenism secondary to chronic sickling and micro infarction of spleen in infancy
what organisms are more likely to cause infection In sicks cell?
encapsulated - pneumococci, h.influenzae
What is a painful crisis?
vaso-occlusion in sickle cell
wat is the common mode of presentation of painful crises?
hand-foot syndrome - dactylitis w swelling and pain in fingers and feet
what is acute chest syndrome?
severe hypoxia w need ofr mechanical ventilation and emergency transfusion
What precipitates acute vast-occlusive crises?
cold dehydration XS stress or exercise hypoxia infection
What can cause acute anaemia in sickle cell?
haemolytic crises
aplastic crises - parvovirus cause complete, temporary cessation of rbc production
sequestration crises - sudden splenic or hepatic enlargement, abdo pain and circulatory collapse from accumulation of sickled cells in spleen
what are long term problems of sickle cell?
short stature, delayed puberty stroke adenotonsillar hypertrophy cardiac enlargement HF renal dysfunction
What is the general management of sickle cell?
- prophylaxis - immunisation from pneumococcal, HiB and meningococcus inf. give daily oral penicillin throughout childhood
- OD oral folic acid due to increased demand caused by chronic haemolytic anaemia
- avoid exacerbations of vast-occlusive crises
What is rx of acute crises of sickle cell?
- Oral/IV analgesia
- Hydration
- Treat infection w abx
- Give oxygen if sats
- Exchange transfusion for: acute chest syndrome, stroke and priapism
What is the treatment of chronic problems in sickle cell?
→ Bone marrow transplant - for most severely affected children w strokes or don’t respond to hypoxyurea - cure rate of 90%
What are potential complications of sickle cell disease?
proliferative retinopathy in adolescence
prone to osteonecrosis of hips and shoulders
what is thalassaemia?
disorder of global chains
What are the types of thalassaemia?
alpha and beta
what type of genetic inheritance is thalassaemia?
autosomal recessive
what populations is thalassaemia more common in?
Mediterranean, india, south east asian
what are the features of beta-thalassaemia trait?
usually asymptomatic
mild hypochromic, microcytic anaemia
What are the features of
failure to thrive and hepatosplenomegaly
microcytic anaemia
HbA2 and HbF raised
HbA absent
What chromosome is the genetic deformity of beta thalassaemia major found?
11
what is the pathophysiology of beta thalassaemia major?
little or no beta chain production, resulting in excess alpha chains, increased HbA2 and HbF
what is the feature of beta thalassaemia major found on head xr?
hair on end appearance of the skull
what does alpha thalassaemia severity depend on?
dependent on whether 1,2,3 or all 4 genes are deleted for alpha globin
What is the management of
repeated transfusions
What chromosomes are the genes for alpha chains?
16
