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571441
Anaemia
Descrição
Paediatrics (Haematological disorders) Mapa Mental sobre Anaemia, criado por v.djabatey em 22-02-2014.
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haematological disorders
paediatrics
paediatrics
haematological disorders
Mapa Mental por
v.djabatey
, atualizado more than 1 year ago
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v.djabatey
mais de 10 anos atrás
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Resumo de Recurso
Anaemia
definition
an Hb level below normal
neonate: Hb< 14 g/dl
1-12 months: Hb< 10 g/dl
1-12 years: Hb<11 g/dl
causes
reduced RBC production
ineffective erythropoiesis
normal/increased rate of RBC production but differentiation or survival of RBCs is defective
e.g. iron def
main causes =
inadequate intake
common in infants
additional Fe needed for rise in blood vol that goes w/ growth & to build up child's Fe stores
1 year old kid needs Fe intake of about 8 mg/day (about same intake as dad)
sources of iron
breast milk
low iron content
but 50% of Fe in it is absorbed
infant formula
supplemented w/ adequate Fe amount
solids introduced at weaning
e.g. cereals
supplemented w/ iron
but only 1% absorbed
high iron sources
red meat
beef
lamb
liver
kidney
oily fish
pilchards
sardines
average iron sources
pulses, peas, beans
wholemeal prods
fortified breakfast cereals with added vit C
dark green veg
broccoli
spinach
dried fruit
raisins
sultanas
nuts & seeds
cashews
peanut butter
foods to avoid in excess in toddlers
cow's milk
low iron content & poorly absorbed
tea
tannin inhibits Fe uptake
high fibre foods
phytates inhibit Fe absorption
caused by
delay in introduction of mixed feeding beyond 6 months old
diet insufficient in iron-rich foods
esp if it contains large amounts of cow's milk
Fe absorption increased when eaten w/ fresh fruit & veg (rich in vit C)
malabsorption
blood loss
clinical features
asymptomatic until Hb < 6-7g/dl
as anaemia worsens, kids tire easily & young infants feed more slowly
any sx and signs of
blood loss
malabsorption
pallor of
conjunctivae
tongue
palmar creases
pica
= inapprop eating of non-food material
e.g. soil, chalk, gravel, foam rubber
adverse effect on behaviour & intellectual function
diagnosis
microcytic hypochromic anaemia (low MCV & low MCH)
low serum ferritin
differentials (of microcytic anaemia)
beta-thalassaemia trait
usually kids of Asian, Arabic or Mediterranean origin
alpha-thalassaemia trait
usually kids of African or Far Eastern origin
anaemia of chronic disease e.g. due to renal failure
Mx
dietary advice
oral Fe supplementation
well tolerated preps that don't stain teeth
Niferex (polysaccharide Fe complex)
Sytron (sodium iron edetate)
continue til Hb normal & then for at least another 3 months to replenish Fe stores
w/ good compliance Hb will rise by 1g/dl per week
failure to respond to this Rx means child isn't getting enough
but ix other causes esp
malabsorption
e.g. due to coeliac disease
chronic blood loss
e.g. due to Meckel divertiulum
NEVER GIVE A BLOOD TRANSFUSION
even kids w/ Hb as low as 2-3 g/dl due to Fe def have reached this level over a long period & can tolerate it
Rx of Fe def w/ normal Hb
i.e. kids w/ low serum ferritin that haven't yet developed anaemia
giving oral Fe is CONTROVERSIAL
Arguments for
Fe needed for brain development
Fe def anaemia assoc w/ behavioural & intellectual def
Arguments against
risk of accidental poisoning w/ oral Fe
oral Fe is toxic
give dietary advice
& offer option of additional Rx w/ oral iron
e.g. folic acid def
chronic inflammation
JIA
chronic renal failure
rare stuff
myelodysplasia
Pb poisoning
diagnostic clues to this =
normal reticulocyte count
abnormal mean cell vol (MCV) of RBC
low in Fe def
raised in folic acid def
complete absence of RBC production (RBC aplasia)
Parvovirus B19 infection
Diamond-Blackfan anaemia (congenital red cell aplasia)
rare (5-7 cases/10^6 live births)
20% of cases have fam hx; rest sporadic
gene mutations in ribosome protein (RPS) genes implicated in some cases
most cases present at 2-3 months old; 25% present at birth
clinical features
sx of anaemia
congenital anormalies
short stature
abnormal thumbs
Rx
oral steroids
monthly RBC transfusions
for kids who are oral steroid unresponsive
stem cell transfusion
Transient erythroblastopenia of childhood
usually triggered by viral infections
same haematological features as D-B anaemia
but TEC
always recovers
usually within several weeks
no fam hx
no congenital anomalies
no RPS gene mutations
rare stuff
Fanconia anaemia
aplastic anaemia
leukaemia
diagnostic clues
low reticulocyte count despite low Hb
normal bilirubin
-ve direct antiglobulin test (Coombs test)
red cell precursors on bone marrow exam
increased RBC destruction (haemolysis)
immune
haemolytic disease of the newborn
autoimmune haemolytic anaemia
common in neonates, but not kids
characterised by reduced RBC lifespan
due to haemolysis (increased RBC destruction) in
the circulation (intravascular haemolysis)
liver or spleen (extravasc haemolysis)
normal RBC lifespan = 120 days & bone marrow makes 173000 RBCs/day
in haemolysis RBC survival lasts a few days
bone marrow prodn rises 8x
so haemolysis only -> aneamia when bone marrow can not make up for premature destructn of RBCs anymore
intrinsic abnormalities
the main cause of haemolytic anaemia in children
red cell mb disorders
hereditary spherocytosis
occurs in 1 in 5000 births in Caucasians
usually autosomally dominantly inherited
but in 20% no fam hx & caused by new mutations
caused by mutations in genes for proteins of RBC mb
spectrin
ankyrin
band 3
-> red cell losing part of mb when it goes through spleen
reduction in surface:vol ratio -> spheroidal shape, so less deformable than normal RBCs
so destroyed in microvasc of spleen
clinical features
fam hx makes diag suspicious
variable manifestations
can be asymptomatic
jaundice
usually develops during childhood
but may be intermittent
may cause severe haem jaundice in 1st few days of life
anaemia
presents in childhood of mild severity (Hb 9-11 g/dl)
but Hb may drop temporarily during infections
mild to moderate splenomegaly-depends on rate of haemolysis
gallstones
due to raised bilirubin excretion
aplastic crises
uncommon
transient (2-4 wks)
caused by parvovirus B19 infection
diagnosis
characteristic blood film
specific tests (not usually needed)
osmotic fragility
dye binding tests
direct antibody test
exclude autoimmune haemolytic anaemia
also assoc w/ spherocytes
so do test if no fam hx of HS
Mx
if mild chronic haemolytic anaemia
oral folic acid
these kids have raised FA req sec to increased RBC prodn
splenectomy
indications
poor growth
trouble sx of anaemia
severe tiredness
loss of vigour
usually deferred till > 7 years old
due to risks of post-splenectomy sepsis
prior to splenectomy all pts must be checked to have had Hib, S. pneumoniae & menC vaccinations
advise lifelong daily oral penicillin prophylaxis
of aplastic crisis from parvovirus B19 infections
1-2 blood transfusions over 3-4 weeks when no RBCs made
symptomatic gallstones
consider cholecystectomy
red cell enzyme disorders
commonest type
glucose-6-phosphate dehydrogenase def
100 million ppl globally affected
high prevalence (10-20%) in ppl of ... origin
central African
Mediterranean
Middle Eastern
Far Eastern
pathogenesis
G6PD is rate-limiting enzyme in pentose phosphate pathway
vital for preventing oxidative damage to RBCs
Red cells w/o G6PD are vulnerable to oxidant-induced haemolysis
G6PD def is X-linked
so mostly affects males
Mediterranean, Middle Eastern & Oriental popns, affected males have low/absent ezyme activity in RBCs
Affected Afro-Caribbeans have 10-15% normal activity
heterozygote girls are usually normal cos they've about 1/2 the normal G6PD activity
females can be affected
if homozygous
extreme Lyonisation
more of the normal than abnormal X chromosomes have been inactivated
(Lyon hypothesis- in every XX cell, one X is randomly inactivated)
clinical manifestations
neonatal jaundice
onset usually in 1st 3 days of life
globally commonest cause severe neonatal jaundce requiring exchange transfusion
acute haemolysis ppted by
infection
commonest ppting factor
certain drugs
antimalarials
primaquine
quinine
chloroquine
Abx
sulphonamides (incl co-trimoxazole)
quinolones
ciprofloxacin
nalidixic acid
nitrofurantoin
analgesics
high dose aspirin
fava beans (broad beans)
naphthalene in mothballs
haemolysis is mostly intravsc
assoc w/
fever
malaise
passing dark urine
urine contains Hb & urobilinogen
Hb level falls rapidly & may drop < 5 g/dl over 24-48hr
diagnosis
measure G6PD activity in RBCs
btw episodes, nearly all pts have normal blood pic & no jaundice & no anaemia
during haemolytic crisis
G6PD levels may be misleadingly high
cos higher [enzyme] in reticulocytes made in higher nos in response to destruction of mature cells
need to repeat assay in steady state to confirm diag
Mx
give parents advice
signs of acute haemolysis
jaundice
pallor
dark urine
list of drugs, chemicals & food to avoid
i.e. ppting factors
transfusions rarely needed even for acute episodes
haemoglobinopathies (abnormal haemoglobins)
cause anaemia by production of abnormal Hb
sickle cell disease
cause= mutation in beta-globin gene
so delayed presentation til > 6 months old
when most HbF present @ birth replaced by adult HbA
commonest genetic disorder in kids in UK
prevalence= 1 in 2000 live births
commonest in kids w/ black parents of tropical African or Caribbean origin
also seen in Middle East and low prevalence in other areas of world except for N. Europe
collective name for haemoglobinopathies in which HbS inherited
HbS forms cos of mutation in codon 6 of beta-globin gene
so glutamine-> valine
3 forms of sickle cell disease
sickle cell anaemia (HbSS)
pt homozygous for HbS- practically all Hb is HbS
have small amounts of HbF & NO HbA
because sickle mutation is in both beta-globin genes
HbSC disease (HbSC)
one HbS inherited from 1 parent & HbC inherited from other parent
HbC formed due to different point mutation in beta-globin
so have no HbA cos they've no normal beta-globin genes
sickle beta-thalassaemia
one HbS inherited from one parent & beta-thalassaemia trait inherited from the other
no normal beta-globin genes & most can't make any HbA
so sx similar to sickle cell anaemia
sickle trait
HbS inherited from 1 parent, normal beta-globin gene from the other
40% of Hb= HbS
don't have sickle cell disease
but are carriers of HbS
can pass HbS to their kids
asymptomatic
IDed by blood test
cause anaemia by absent/reduced prod of HbA
alpha thalassaemia
cause= deletions or mutations in alpha-globin gene
beta-thalassaemia
cause= mutation in beta-globin gene
so delayed presentation til > 6 months old
most HbF present @ birth replaced by adult HbA
->
anaemia
hepatomegaly & splenomegaly
increased blood levels of unconj biliirubin
excess urinary urobilinogen
diagnostic clues
reticulocyte count (called polychromasia on blood film cos reticulocytes have characteristc lilac colour)
unconj bilirubinaemia & increased urinary urobilinogen
abnormal appearance of RBCs on blood film
spherocytes
sickle-shaped
very hypochromic
+ve direct antiglobulin test
only if immune cause
this test IDs antibody-coated RBCs
increased RBC precursors in bone marrow
blood loss
relatively uncommon cause in kids
anaemia of prematurity
combo of reduced RBC productn, increased haemolysis & blood loss
blood loss
fetomaternal bleeding
chronic GI blood loss
Meckel diverticulum
inherited bleeding disorders
von Willebrand disease
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