haematology/oncology Flashcards
what is pernicious anaemia? (pathology)
B12 (from food) absorbed with intrinsic factor (from parietal cells in stomach) absorbed together in terminal ilium
In PA - IgA attacks parietal cells preventing secretion of intrinsic factor so no absorption of b12 - macrocytic anaemia
how does Crohn’s disease cause macrocytic anaemia?
Crohn’s has a predilection for the terminal ilium
inflammation/resection of terminal ilium -> inability to absorb IF+B12
so get macrocytic (+megaloblastic) anaemia
how does gastric bypass cause macrocytic anaemia?
bypass stomach where parietal cells which secrete IF are - so B12+IF cannot be absorbed by terminal ilium - macrocytic anaemia
if impaired absorption of b12 - how should b12 be replaced?
IM
apart from macrocytic anaemia, why is b12 deficiency a problem?
neuro sx - DCMLS (dorsal coloumn medial lemniscus system) - sensory pathway responsible for: - 2 pt discrimination - proprioception - vibratory sense IRREVERSIBLE
what other disease causes similar symptoms (neuro) to b12 deficiency?
syphilis
what does Schilling’s test determine?
whether b12 deficiency is nutritional or from impaired absorption (usually can get from Hx)
how does Schilling’s test work?
give IM B12 - saturate B12 in liver, then give PO B12
- > check urine: if + for b12 they were able to absorb it so their previous problem was nutritional deficiency
- > if urine - for B12 - couldn’t absorb PO - absorption problem
non-megaloblastic causes of macrocytic anaemia:
liver cirrhosis
ETOH
drugs - chemo (5FU)/Ara-C/HAART (AZT)
metabolic conditions
how do you differentiate between the megaloblastic and non-megaloblastic macrocytic anaemias?
blood smear - megaloblastic if hypersegmented neutrophils - >5 nuclear segments
how to differentiate between megaloblastic macrocytic anaemias if b12 and folate levels both on lower side of normal?
MMA (methylmalonic acid) test - raised if b12 deficiency, normal if folate deficiency
what are the 4 types of microcytic anaemia?
IDA
ACID
Thalassaemia
Sideroblastic
who gets IDA (generally which type of patients?
slow bleeds - subacute haemorrhages
male, >50, colon ca, +FOBC
female >20 menorrhagia
what do iron studies show in IDA (remember the silo metaphor from Dustyn):
Fe low
Ferritin low
TIBC (transferrin) high
transferrin saturation level reduced
what do iron studies show in ACID and why? (silo metaphor)
Fe low
Ferritin high
TIBC low
body’s cells can survive for some time without iron, but bacteria need iron to survive, so as an acute response, body cuts off Fe supply. In chronic inflammation, same response happens - pathology of ACID
what type of pt gets ACID?
chronic inflammatory disease AI
eg lupus or RA
usually asx anaemia
tx for ACID?
usually nothing
in severe cases EPO
but rather control disease
giving iron will do nothing
pathology of thalassaemia?
globin problem
minor - asx
major - transfusion-dependent (monthly)
what are iron studies like in thalassaemia?
normal - problem with globin, not haem
if normal iron but macrocytic anaemia, which test do you do if suspect thalassaemia?
HgB electrophoresis will show b-thalassaemia
if normal - a-thalassaemia
also high bili
due to blood transfusions containing a years worth of iron in them, what cx and f/u tx needed in transfusion dependent thalassaemia pts?
iron overload
de-furox-amine
pathology of sideroblastic anaemia:
iron gets stick in mitochondria
sideroblastic RBCs are trying to make regular RBCs
bone marrow throws more iron at them
the sideroblastic cells themselves are loaded with iron but can’t use it
what iron studies show in sideroblastic anaemia:
what test confirms
Fe high
others normal/irrelevant
biopsy shows a ring sideroblast
reversible causes sideroblastic anaemia:
drugs
etoh
lead