Macrocytosis and macrocytic anaemia Flashcards
macrocytosis and macrocytic anaemia are the same thing, true or false
false
define macrocytic anaemia
anaemia with red cells being abnormally larger than normal (^MCV)
what are the units of MCV
femtolitres
in a blood film, what is used as reference for RBC size
the nucleus of a small, mature lymphocyte is used as a reference for RBC size as it is unchanging
what are the main causes of macrocytic anaemia
genuine / true
spurious / false
what are genuine causes of macrocytic anaemia
megaloblastic
non-megaloblastic
what accumulates in developing erythroblasts/normoblasts
Hb
what happens when Hb concentration has reached threshold
erythroblasts stop dividing and enucleation occurs to become a reticulocyte
define erythroblast
normal red cell precursor with a nucleus
define megaloblast
large red cell precursor with an immature nucleus - open chromatin seen
what is the main cause of megaloblastic anaemias
lack of red blood cells due to defects in DNA synthesis and nuclear maturation
RNA synthesis and Hb accumulation are preserved in megaloblasts, true or false
true
what happens in the lineage of megaloblasts
EPO causes expansion of primitive precursors
cell division reduces and apoptosis occurs resulting in fewer overall cells
what happens when Hb concentration threshold is reaches in a megaloblast
enucleation occurs which leaves behind a bigger than normal red cell ie macrocyte
what are causes of megaloblastic anaemia
B12 deficiency
folate deficiency
drugs
inherited conditions
what are B12 and folate and their functions
essential cofactors in biochemical reactions
blood cells - DNA synthesis and nuclear maturation
neuro - DNA modification and gene activity
in which foods is B12 found
meat and meat products
describe the absorption of B12 in the GI tract
acid in the stomach causes B12 to dissociate from meat and bind to haptocorrin
gastric parietal cells secrete IF
B12 and haptocorrin compound and IF travel to gut
pancreatic secretion increase pH and cause B12 to dissociate from haptocorrin and bind to IF
B12 and IF complex travel to distal gut and are internalised by cells with cubulin receptors in ileum
what is pernicious anaemia
autoimmune condition attacking gastric parietal cells resulting in IF deficiency and B12 malabsorption and deficiency
how is folate absorbed in the gut
converted to monoglutamine
and absorbed in jejunum
how long do B12 stores last in the body
2-4 years
how long do folate levels last in the body
4 months
what are symptoms of B12 and folate deficiency
fatigue, SOB, pallor
weight loss, diarrhoea, infertility
sore tongue, jaundice
developmental delay
symptoms of B12 deficiency alone
neurological: neuropathy dementia psychiatric SCDC
how can you diagnose megaloblastic anaemia in the lab
macrocytic anaemia (low Hb, raised MCV) pancytopaenia in some blood film = macrovalocytes + hypersegmented neutrophils B12 + folate assays - not accurate antibodies: anti-IF, anti-GPC
causes of B12 deficiency
diet atrophic gastritis pernicious anaemia gastrectomy SBBO coeliac crohns inherited deficiencies
causes of folate deficiency
diet alcoholics pregnancy malignancy malabsorption haemolysis anticonvulsants
treatment of megaloblastic anaemia
treat cause
lifelong B12 injections
folic acid tablets 5mg PO OD
only transfuse if emergency
causes of non-megaloblastic anaemia
red cell membrane changes
may or may not be associated with anaemia:
- alcohol
- liver disease
- hypothyroidism
marrow failure - associated with anaemia
- myelodysplasia
- myeloma
- aplastic anaemia
what is spurious macrocytosis
normal RBC volume but MCV is high
causes of spurious macrocytosis
reticulocytosis
cold agglutins
why can patients with pernicious anaemia appear mildly jaundiced
due to intramedullary haemolysis
what is ineffective erythropoeisis
RBCs die prematurely in bone marrow
pancytopaenis can complicate severe megaloblastic anaemia, true or false
true
nuclear maturation defects only effect red blood cells, true or false
false, it can affect al lineages
in someone with macrocytic anaemia, if you did a bone marrow aspirate, would it be hypo/normo/hypercellular and why
hypercellular
there is a problem of cell division where you either produce large progeny or cells undergo apoptosis so there is a lot of premature red cell death
hypoxia is detected by kidneys which release EPO which increases cell turnover. There is a lot of activity in the bone marrow, but not much to show for it.
why might you get jaundice in megaloblastic macrocytic anaemia
defective cell division means there is also premature RBC destruction IN THE MARROW and apoptosis of cells, this releases Hb which is broken down to bilirubin causing icterus/jaundice
