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haematology > anaemia, haemolysis and haemolytic deficiencies > Flashcards

anaemia, haemolysis and haemolytic deficiencies Flashcards

1
Q

what is blood made up of?

A

plasma - contains plasma proteins, electrolytes, hormones and nutrients
platelets
white cells
red cells

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2
Q

define anaemia

A

deficiency of healthy red blood cells

this can be a reduction in Hb, red cell count or haematocrit

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3
Q

what are normal Hb levels and how are they derieved?

A

normal levels are derieved from a normal distribution of the population

Men - more than 130g/L 
Women - more than 120g/L 
Pregnant women - more than 110g/L - this is due to an increase in circulating volume which dilutes the red cells rather than a reduction in red cells 
Children 6-59 months - more than 110g/L 
Children 5-11 years - more than 115g/L 
Children 12-14 years - more than 120g/L
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4
Q

what does a normal blood film look like?

A

(look in notes for image)

RBCs should be round and the pale bit in the middle should take up around 1/3 of the cell (more is hyper chromia which suggests iron deficiency of thalassemia/ thalassaemia trait)

platelets will be small purple dots

neutrophils may be seen as a circle with lobes inside. 2-5 lobes is normal.

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5
Q

what does MCV tell you about anaemia?

A

It can help you to determine the cause

  • anaemia with a low MCV is microcytic (less than 80fL)
  • anaemia with a normal MCV is normocytic (80-95fL)
  • anaemia with a high MCV is macrocytic (more than 95fL)
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6
Q

what are the causes of microcytic anaemia?

A

thalassaemia and thalassaemia trait
iron deficiency
anaemia of chronic disease
sideroblastic anaemia

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7
Q

what are the causes of normocytic anaemia?

A

anaemia of chronic disease
acute blood loss
mixed haematinic deficiencies
bone marrow failure - aplastic anaemia, drugs eg. chemotherapy

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8
Q

what are the causes of macrocytic anaemia?

A 
megaloblastic anaemia 
myelodysplasia 
haemolytic anaemia 
liver disease 
alcohol 
drugs 
hypothyroidism 
pregnancy
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9
Q

what type of anaemia will blood loss cause?

A

acute blood loss will cause normocytic anaemia as loss of red cells quickly but also loss of plasma as they are losing whole blood. This means the Hb concentration remains the same
Plasma volume expands to maintain BP which causes dilution of red cells so Hb falls and MCV remains the same

Chronic, slower blood loss will cause microcytic anaemia because as the blood is lost more RBCs will be made to compensate which uses up more iron stores causing iron deficiency anaemia

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10
Q

what are the different congenital causes of anaemia?

A

membrane defects

  • hereditary spherocytosis
  • hereditary elliptocytosis

haemoglobin defects

  • sickle cell anaemia
  • thalassaemia

enzyme defects

  • G6PD deficiency
  • pyruvate kinase deficiency
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11
Q

what are the different acquired causes of anaemia ?

A 
inability to make red cells caused by multiple causes: 
deficiency in
- iron (dietary, malabsorption, bleeding)
- B12
- folate 
bone marrow pathology 
- aplastic anaemia
- myelodysplasia 
- myeloma 
displacement in bone marrow 
- leukaemia 
- myelofibrosis 
- other cancer
chronic disease 
- renal failure 
- other chronic disease 
destruction of red cells through 
haemolysis 
- immune
- non immune 
bleeding
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12
Q

how does chronic disease cause anaemia?

A

hepcadin is produced by the liver and is necessary for iron metabolism.
In chronic disease there is an increase in hepcadin which stops iron from leaving and you therefore get a relative iron deficiency causing anaemia.

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13
Q

what are the signs of symptoms of iron deficiency anaemia?

A

signs and symptoms of anaemia

  • fatigue
  • breathlessness
  • palpitations
  • tinnitus - turbulant flow of carotid artery can be heard in the ears
  • pallor
  • tachycardia
  • flow murmur or hyperdynamic circulation

features specific to iron deficiency

  • koilonychia - spooning of the nails
  • restless legs
  • pica - eat non food items that are high in iron such as soil and paint
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14
Q

what is the next step when you have diagnosed someone with iron deficiency anaemia?

A

iron deficiency is not a diagnosis and you need to establish the cause

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15
Q

what are the causes of iron deficiency anaemia?

A
  • poor intake in diet
  • poor absorption - chrons disease, coeliac disease
  • increased requirement - pregnancy
  • iron loss - GI bleeding, cancer, menorrhagia…
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16
Q

how is iron deficiency diagnosed

A
  • history and examination - include diet and bleeding
  • FBC and film - microcytic hypochromic anaemia (low Hb and low MCV), target cells, pencil cells on blood film see pictures in notes
  • ferratin studies - this will be low in iron deficiency and high in inflammation so it may be falsely normal if the iron deficiency is caused by inflammation eg. IBD
  • iron studies - serum iron, transferrin saturation (carrier molecule for iron), total iron binding capacity
17
Q

how can you use blood tests to differentiate between iron deficiency and anaemia of chronic disease?

A

iron deficiency

  • low ferratin
  • low serum iron
  • low transferrin saturation
  • high TIBC or transferrin

chronic disease

  • normal ferratin
  • low serum iron
  • low transferrin saturation
  • low TIBC or transferrin
18
Q

what is functional iron deficiency

A

anaemia of chronic disease/ anaemia of acute disease

there is an evolutionary advantage to keeping iron away from bacteria and therefore there are increased stores in infection/ inflammation and decreased absorption due to hepcadin block at the enterocyte basolateral membrane. This means that iron is not available for erythropoitin causing functional iron deficiency.

there are other factors that contribute to iron deficiency anaemia such as reduced erythropoietin in renal disease.

19
Q

how is iron deficiency anaemia managed?

A

First you need to find the underlying cause. This could be done through history eg. menstrual or diet history. Sometimes and OGD or colonoscopy may be needed to find source of bleeding etc.
If possible, treat this underlying cause eg. dietary advice or the pill for heavy menstruation.

then you also need to give supplementary iron. This can be done orally or IV

20
Q

How is oral iron supplementation done?

A

100-200mg per day is given
different preparations are available
this can be poorly tolerated due to a failure to absorb so dose may need to be reduced, taken on an empty stomach, taken with orange juice and avoid tea. Warn the patient of the side effects.
Hb levels are monitored whilst taking iron tablets and they are continued for 3 months post normal Hb levels to replenish stores.
If no cause is found the iron supplementation may have to continue indefinately

21
Q

how is IV iron supplementation used?

A

it is given to people who are severely anaemic, do not tolerate oral iron or when iron stores need to be replenished quickly (pregnancy, before surgery etc)

it is contraindicated in active bacterial infection and decompensated liver disease
need to be careful if there is a history of autoimmune conditions or severe allergic reactions

given in different preparations and the larger dose of iron that is delivered gives a faster increase in Hb

22
Q

what is folate?

A

family of compounds
extra carbon group reduced at different positions, polyglutamated
absorbed through proton-coupled transporter in duodenum
lost in urine, sweat and skin
require 100micrograms per day

23
Q

what are the causes of folate deficiency?

A

low intake - sources of folate include spinach, liver, yeast, greens, nuts, fortified foods,
impaired absorption - coeliac disease, chrons disease, drugs
increased requirement - haemolysis, pregnancy, prematurity, inflammation
increased loss - dialysis, drugs

24
Q

how are folate levels measured ?

A
  • ELISA technique
  • serum folate - this tells you about recent folate intake. May be increased in B12 deficiency, acute liver disease, blind loop syndrome and a haemolysed sample
  • red cell folate - low in B12 deficiency and falsely normal in a recent transfusion or high reticulocyte count
25
Q

how is folate supplementation given?

A
  • almost always normal
  • 5mg per day for 4 months then continue depending on the cause
  • well tolerated and absorped
26
Q

what is B12?

A 
a family of compounds 
plays a role in DNA synthesis and making succinyl A for the Krebs cycle 
require 5-30mg per day 
passive absorption - duodenum and ilium 
active absorption 
- hepatocorrin - saliva 
- intrinsic factor - stomarch 
- cubilin receptor - ileum 
- trancobalamin - circulation 
- recycled in the enterohepatic circulation
27
Q

what are the features of B12 deficiency?

A

features of anaemia

neurological features

  • parasthesia
  • muscle weakness
  • difficulty walking
  • confusion
  • peripheral neuropathy
  • long tract demyelination
  • dementia
  • psychosis
28
Q

how may treatment of folate deficiency cause B12 deficiney?

A

overzealous folate replacement in presency of B12 deficiency

29
Q

what are the causes of B12 deficiency?

A

poor intake - sources of B12 are through liver, kidney, shellfish, fish, chicken, eggs, cheese and milk
malabsorption - gastric, ileal, drugs
loss - nitric oxide
apparent deficiency in oral contraception, HRT and pregnancy

30
Q

how are B12 levels measured?

A

B12 assay

31
Q

what is pernicious anaemia?

A

this is the most common cause of B12 deficiency
it is associated with other autoimmune disorders
common in older women
causes destruction on intrinsic factor causing impaired absorption of B12
diagnosed through measuring antibodies

32
Q

how is B12 supplementation given?

A
  • intramuscually as it cannot be absorbed
  • continue indefinately unless clear reversable cause
  • oral supplementation can be given to ba absorped through passive route
  • may need routine post gastrectomy or ilectomy
33
Q

what are the signs and symptoms of B12 and folate deficieny?

A

signs and symptoms are indistinguishable as they occur together

  • signs and symptoms of anaemia
  • jaundice
  • glossitiis
  • angular cheilitis
  • mild fever
  • skin hyperpigmentation
  • infection and bleeding if alos thrombocytopaenia or neutropenia
  • infertility
  • neural tube defects in babies
34
Q

what does B12 and folate deficiency look like on a blood film?

A

look in notes for image

oval hypochromic red blood cells - macrocytic
neutrophils are hyper segmented (more than 5 lobes)
B12 and folate deficiency are indistinguishable except with assays

35
Q

how is haemolytic anaemia diagnosed?

A
  • FBC
  • blood film - may show feature of the cause of haemolysis
  • LDH - measurement of cell turnover which will be raised
  • haptoglobin - measurement of free haem
  • unconjugated bilirubin - will be raised as a breakdown product of RBCs
  • reticulocyte count - young red cells indicating high cell turnover
  • ## direct antiglobulin test - this will not tell you whether or not the patient is in haemolysis but it will tell you in the presence of haemolysis whether there is an autoimmune cause
36
Q

outline the causes of haemolysis

A

may be immune or non-immune

immune causes

  • warm
  • mixed
  • cold

non immune causes may be congenital or acquired
acquired
- microvascular
- macrovascular
congenital
- membrane structure defect - hereditory spherocytosis, hereditory eliptocytosis
- enzymopathy - G6PD deficiency, PK deficiency
- haemoglobinopathy - sickle cell anaemia, thalassaemia

37
Q

what is warm and cold immune haemolysis?

A

warm - IgG, red cells are destroyed in the spleen

  • associated with other autoimmune conditions especially ITP
  • may be precipitated by cancer or infection
  • treated with steroids, splenectomy or rituximab

cold - IgM, antibodies are active at cooler temperatures causing intravascular haemolysis in the peripheries. Red cells agglutinate (stick together)

  • associated with EBV, micoplasma pneumonia and lymphoma
  • does not respond to steroids
  • patient needs to be kept warm and transferred though a blood warmer and underlying infection or lymphoma to be treated

haematology (5 decks)

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