anaemia (post op) Flashcards
discuss post op anaemia
very common following major surgery (90%)
caused by variety of factors- frequent blood sampling, bleeding intra op, reduced nutritional intake, prev anaemia
hepcidin related nutritional absorption and iron release from cells also plays a roll. Hepcidin is associated with inflammation levels.
discuss the classification of anaemia
hyperproliferative normocytic- more than 2% of cells are reticulocyte (precursors) indicating acute blood loss or haemolysis.
hypoproliferative- normal levels of reticulocytes (<2%) disorder of decreaced RBC production
macrocytic Megaloblastic- DNA maturation and production- results in large immature RBC + hypersegmented neutrophils
non-megaloblastic- all other forms of macrocytic anaemia which DNA synth is normal.
how much to loose and when to transfuse
can be fatal if 40% of body volume is lost
transfusion of 70, or 80 if going to undergo cardiac or orthopaedic surgery, or underlying cardiovasc diseases (with many exemptions)
discuss anaemia of chronic disease
reduction in RBC + evidence of immune system response.
generally a reduction in RBC due to inflammation-mediated reduction in red blood cell production (and sometimes survival)
normocytic normochromic
il-6 is an important interleukin which can cause ACD
risk factors for anaemia of chronic disease
autoimmune disorders, malignancy (due to host and tumor released cytokines), acute/ chroni infection, critical illness, major trauma, or major surgery with delayed recovery, chronic disease ( dec EPO, + EPO resistance due to chornic inflam)
ix to order in anaemia of chronic disease
blood work essentially, full blood coint including
blood smear
MCHC
MCV
WBC + differential,
serum ferratin
iron binding capacity
serum iron
absolute reticulocyte count
important to be mindful of ACD when there is absence of risk factors for other types of anaemia (such as alcohol, drugs chemicals etc)
ferratin for deficiency anaemia
what is management for ACD
generally it is intrinsically linked to the underlying disease. modification or cure of the disease will cause anaemia to rise again.
blood transfusion or Erythropoetin stimulating agents can be used if the condition will take time or is uncurable.
list causes of microcytic anaemia
iron deficiency
thalassaemia
discuss red blood cell indices, specifically MCHC
MCHC indicates the amount of haemoglobin per unit volume.
34 ± 2 g/dl.
there are no hyperchromic anaemias.
ordered as part of a whole blood work up.
usually find microcytic hypochromic goes together.
MCV- average size of Hb
MCH- average haemoglobin contant of RBC.
causes and treatment of macrocytic anaemia
deficiencies in folic acid and vitamin B12. chronic alcohol use the most common.
folic acid: diminished intake, (alcohol abuse, malnutrition), increased consumption (hemolysis or pregnancy), malabsorption (familial, gastric bypass, or medications like cholestyramine or metformin).
B12: (malnutrition), malabsorptive states (atrophic gastritis either autoimmune or non-autoimmune from Helicobacter pylori, tapeworm infection, gastric bypass, ileal resection), or presence of antagonists (nitrous oxide). Drugs that impair DNA synthesis are folic acid analogs (ex. methotrexate, trimethoprim-sulfamethoxazole), nucleic acid analogs (5-fluorouracil, zidovudine), and others (hydroxyurea, pentamidine, phenytoin, pyrimethamine, sulfasalazine, triamterene).
treatment: replace folate or b12 and treat underlying cause. Give folic acid orally, 1 mg to 5 mg daily. b12 supplementation should be encouraged as only this will resolve neurological defects. 1000 micrograms daily for 1/12.
remember increased consumption can be a cause
investigation of macrocytic anaemia
history
labs
serum b12 and folate levels to assess if these are culprits.
if these are normal may need to look into bone marrow
haemolytic anaemia. what is it, RF, presentation, Ix.
premature destruction of red blood cells with insufficient replacement. NOT blood loss.
risk factors: autoimmune disorders, lymphoproliferative disorders. med, middle east, sub Sahara Africa, south east asia.
paroxysmal nocturnal haemoglobinuria. prosthetic heart valve. exposure to cephalosporins, fava beans, thermal injury.
may present with jaundice- increased bilirubin due to destruction. splenomegaly may be present.
Ix: FBC, MCHC, reticulocyte count, peripheral smear, bilirubin (unconjugated), LDH, urine analysis. Coombs test- (to see if IgG bound to RBC.) if +ve immune aetiology, if negative non-immune gives basis for ‘hot’ or ‘cold’.
Rx of haemolytic anaemia.
remove underlying condition, consider corticosteroid, rituximab if 3/52 steroid don’t work
splenectomy 2nd line (removal of primary centre for destruction) or earlier if due to a specific condition.
if autoimmune then immune suppressant.
cold much harder to treat, as possibly still autoimmune but no cause specifically identified, NICE says rituximab can be offered first line.
discuss anaemia in pregnancy
Hb below 110 g/L
fatigue, dyspnoea, and headache.
pallor and atrophic glossitis. Less common signs include tachycardia, nail changes, and angular cheilosis.
full blood count should be assessed at booking and 28 weeks,
assess serum ferratin and suppliment iron. (also check thalassemia and sicklecell traits). ferrous sulphate or ferrous fumarate 200 mg two or three times daily
if less than 70- refer to 2nd care.
likely more of a dilutional anaemia than a true reduction in RBC mass as blood volume increases significantly.
Blood transfusion is almost always required when the Hb is less than 60 g/l above 70 they try and avoid it.
causes of microcytic anaemia
TAILS
thalassaemia
anaemia of CD
iron deficiency
lead poisoning
sideroblastic
causes of normocytic anaemia (80-100)
Haemolytic
haemorrhage
aplastic
anaemia of chronic disease (early)
anaemia of CKD
autoimmune
causes of macrocytic anaemia
megaloblastic- large immature
folic and B12 def- DNA maturation
medication side effect
non-megaloblastic- pregnancy
myelodysplastic syndrome
alcohol
drugs(azathiaprine), liver disease, hypothyroidism
investigation - blood film
causes of normocytic anaemia
reduction in EPO- CKD
bleeding- haemorhage
chronic disease - main cause
causes of macrocytic anaemia
vitamin b12
folate
alcoholism / liver disease
how do we get rid of iron
other than menstruation and epithelial shedding there is no mechanism to get rid
small bowel enterocites store ferratin as mucosal ferratin and they are shed reguarly.
liver will control ferroportin channel which allowes it into the blood.
routes of iron supplimentation
oral- but gives constipation- can only absorb 1 tab a day
iv- can give bad anaphylaxis
both equally effacious but obs have side effect profiles
blood transfusion but the nuclear option.
pernicious anaemia
lack of absorbtion of B12 in the gut
requires presence of intrinsic factor (terminal ileum)
IF can be attacked by the immune system- autoantibodies
can get some pretty mad blood results but try and treat deficiency first before thinking cancer
warm + cold autoimmune haemolytic anaemia
warm- IgG mediated
DAT +ve
autoab binds to rbc at 37 degrees
removed by RE macrophages
part of RBC membrane is lost- spherocites
destroyed in the spleen prematurely
extravascular
50% idiopathic
Cold- IgM metiated- look at compliment
primary- abs bind at 4 degrees. agglutination and sticky.
worse in the cold
assoc with acrocyyanosis, raynauds, intravascular haemolysis.
triggered by pneumonia sometimes (mycoplasma), EBV.
for warm- steroids are effective.
cold- keep warm
what is MAHA
microangiopathic haemolytic anaemia
mechanical destruction of cells.
DAT negative (not immune)
have schistosites on blood film
