Paediatrics: Haem/Onc Flashcards
describe how fetal and adult Hb have a different affinity for oxygen ?
HbF has a greater affinity for oxygen at any given partial pressure of oxygen
describe the structure of fetal and adult Hb ? number of subunits ? what subunits ?
both have 4 subunits
- HbA: 2 alpha + 2 beta subunits
- HbF: 2 alpha + 2 gamma subunits
when does the product of HbF decrease and HbA increase ? what is the ratio at birth
from 32-36 weeks gestation: production of HbF decrease and HbA increases so at birth about 50:50
when is most HbF gone ?
by 6 months there is v little HbF (mostly HbA)
Why does sickle cell disease not affect HbF ?
genetic abnormality => sickling of beta subunit (=> so no sickling in HbF as no beta unit)
what is anaemia ?
low Hb conc secondary to underlying disease
what are some causes of anaemia in infancy ? (5)
- physiologic anaemia of infancy
- anaemia of prematurity
- blood loss
- Haemolysis
- twin-twin transfusion
what is physiologic anaemia of infancy ? describe the physiology - as a result of what ?
there is a normal dip in Hb at around 6-9 weeks
- high oxygen at birth => -ve feedback => reduced EPO from kidneys => low Hb production by bone marrow
name things that would cause anaemia as a result of Haemolysis ? (3)
- haemolytic disease of the the Newborn
- sickle cell disease
- hereditary spherocytosis
- G6PD deficiency
what is haemolytic disease of the newborn ?
rhesus antigen incompatibility => Haemolysis, anaemia + increased bilirubin
what is the investigation to do for haemolytic disease of the newborn ?
direct Coombs test (DCT) used to check fo immune haemolytic anaemia
causes of anaemia in older children ?
- Iron deficiency
- Blood loss (mesntruaiton)
less common: sickle cell, thalassaemia, leukaemia
how is anaemia categorised ?
based on size (MCV)
causes of microcytic anaemia ? acronym ?
TAILS
- Thalassaemia
- Anaemia of chronic disease
- Iron deficiency
- Lead poisoning
- Sideroblastic anaemia
cause of narmacytic anaemia ? acronym ?
AAAHH
- Acute blood loss
- Anaemia of chronic disease
- Aplastic anaemia
- Haemolytic anaemia
- hypothyroidism
(and pregnancy ?)
causes of macrocytic anaemia ?
- B12 + folate deficiceiy
- alcohol
- Reticulocytosis
symptoms of anaemia specific to iron deficiency ? (2)
- Pica
- Hair loss
why is iron important ? in the body
bone marrow require iron to make haemoglobin
what could cause iron deficiency ? (3)
- dietary insufficiency
- Loss of iron (heavy mesntruation)
- inadequate iron absorption (crohns, coeliac)
where is most iron absorbed ? name a condition required for this ?
- Duodenum + jejenum
- required acid for absorption
how does crohns and coeliac cause iron deficiency ? PPI use ?
- PPI => reduce acid => reduce iron absorption
- Coeliac + crohns => jejunal/duodenal inflam => inadequate absorption
what is leukaemia ? cancer of what ? leads to unregulated what ?
cancer of a particular line of stem cells of bone marrow (bone marrow/blood cancer) => unregulated production of certain types of blood cells (different overproduction depending on which cell lineage involved))
depending on what two factors is leukaemia classified ?
- how rapidly they progress (chronic, acute)
- the cell line affected (myeloid, lymphoid)
what cells can lymphoid stem cells give rise to ? (2)
(WBC)
- Lymphocytes
- Plasma cells