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3MB Haematology > Microcytic anaemia > Flashcards

Microcytic anaemia Flashcards

1
Q

Mnemonic for remembering the causes of microcytic anaemia

A

TAILS

Thalassaemia
Anaemia of chronic disease (normochromic picture)
Iron deficiency anaemia
Lead poisoning
Sideroblastic anaemia

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2
Q

History of a normal haemoglobin level associated with a microcytosis

A

Microcytic anaemia

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3
Q

A history of a normal haemoglobin level associated with a microcytosis but not at risk of thalassaemia

A

Polycythaemia rubra vera - iron-deficiency secondary to bleeding

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4
Q

New onset microcytic anaemia in elderly patients should be..

A

Urgently investigated to exclude underlying malignancy

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5
Q

How is Hb concentration measured?

A

Spectrophotometric method

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6
Q

How to measure haematocrit

A

Automated cell counters calculate the hematocrit by multiplying the red cell number by the mean cell volume

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7
Q

T or F: In rare situations, HB/hct are not a good marker of anaemia

A

True - rapid blood loss and haemodilution are examples of this

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8
Q

What can cause decreased production of HB?

A

Hypoproliferative anaemia (reduced amount of erythropoiesis)

Maturation defect (erythropoiesis is active but ineffective) - Failure to produce Hb (a cytoplasmic defect) or cell division (a nulcear defect)

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9
Q

What can cause decreased destruction of of HB?

A

Blood loss
Haemolysis

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10
Q

If MCV low (microcytic) consider problems with..

A

Haemoglobinisation

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11
Q

If MCV high (macrocytic) consider problems with..

A

Cell division ie maturation

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12
Q

Explain the pathophysiology of microcytic anaemia..

A

Iron, porphyrin ring, globins are needed to make HB (if lacking then MA occurs)
Nuclear machinery is intact so cells keep dividng - for this to stop you need HB accumulation but this response is delayed
So more cell divisions occur and the cells are smaller + hypochromic

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13
Q

Where is iron available?

A

Liver stores
Macrophages
But mostly in RBCs

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14
Q

T or F: Half the volume of blood gives you the mg of iron

A

True

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15
Q

T or F: Iron metabolism occurs in a closed system

A

True - only able to absorb a small amount of iron, tiny amount in circulation moving to/from storage site to being utilized (by marrow)

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16
Q

Circulating iron is bound to..

A

Transferrin

It is transferred to the bone marrow macrophages that regulate iron uptake by transferrin receptor expression. They ‘feed’ iron to red cell precursors

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17
Q

Iron turnover in the plasma pool is slow/fast

A

Fast (4mg in pool and move 20mg/day)

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18
Q

Iron is stored in _______ mainly in the liver

A

Ferritin

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19
Q

What are the available tests to assess iron status

A

Functional iron
Transported iron
Storage iron

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20
Q

What is transferrin?

A

A protein with two binding sites for iron

21
Q

What is the function of transferrin?

A

Transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferrin receptors (especially erythroid marrow)

22
Q

% saturation of transferrin with iron is a measure of..

A

Iron supply

Reduced in iron deficiency
Reduced in anaemia of chronic disease
Increased in genetic haemachromatosis

23
Q

Why is there only a tiny amount of ferritn in the serum?

A

Reflects intracellular ferritin synthesis in response to iron status of the host

24
Q

T or F: Serum ferritin is easily measured but an indirect
measure of storage iron

A

True

25
Q

Low ferritin means..

A

Iron deficiency

26
Q

Iron deficiency can be confirmed by a combination of _______________ and _______________

A

Iron deficiency can be confirmed by a combination of anaemia (decreased functional iron) and reduced storage iron (low serum ferritin)

27
Q

Consequences of
negative iron balance

A

Exhaustion of iron stores (ferritin falls)
Iron deficient erythropoiesis then starts (MCV falls)
Anaemia develops
Epithelial changes (skin, koilonychia, angular chelitis)

28
Q

Causes of iron deficiency

A

Insufficient dietary iron
Gastrointestinal, menstrual, urinary bleeding
Malabsorption - absorbed in the proximal small bowel as non-haem iron needs acid environment for absorption

29
Q

Give examples of malabsorption causes in iron deficiency

A

Coeliac disease
Achlorhydria

30
Q

Iron absorption can be increased by..

A

Iron supplements

31
Q

T or F: Iron replacement therapy may relieve anaemia
symptom without treating the underlying problem

A

True

32
Q

Useful ancillary measures of iron deficiency

A

Improve iron intake - review diet, haem and non haem iron, improve gastric acidity

Review other medication eg anticoagulants, proton pump
inhibitors

33
Q

T or F: Ferritin (iron stores) will not rise till after Hb returns to normal. MCV will rise as new, well haemoglobinised red cells are made

A

True

34
Q

Rise in Hb is limited by..

A

Thee ability of the marrow to upregulate production of red cell

Healthy marrow can increase Hb concentration by 7- 10g/l
per week if well supplied with iron

35
Q

Tx for iron deficiency

A

Oral iron replacement therapy - ferrous sulfate, gluconate and fumarate (taken 30 minutes before a meal or 2 hours before taking other medications)

Can take with small amounts of food if can’t tolerate GI side effects

36
Q

Avoid taking oral replacement therapy with..

A

Milk, calcium, and antacids, high fibre foods, or caffeine

37
Q

Which iron preparation is used in paediatrics?

A

Sodium feredetate (sytron) - liquid prep

38
Q

Next step if oral iron tx was unsuccessful

A

Parenteral (IV) Iron

39
Q

How is the dose for parenteral (IV) iron calculated?

A

Degree of anaemia and patient
weight

40
Q

Regardless of route used, when giving iron always..

A

Monitor response

41
Q

Macrocytic anaemia (low RBC)
Pancytopenia (all cells low)
Blood film shows macrovalocytes and ‘hypersegmented’ neutrophils

A

B12/folate deficiency

42
Q

When is red blood cell transfusion done?

A

Only if potentially life-threatening anaemia

43
Q

Causes of non-megaloblastic macrocytosis (red cell membrane changes)

A

Alcohol, liver disease, hypothyroidism (may not be assoc. with anaemia)
Marrow failure (Myelodysplasia, myeloma, aplastic anaemia - assoc. with anaemia)

44
Q

What is Spurious Macrocytosis?

A

False macrocytosis. The volume of the mature red cell is NORMAL, but the MCV is measured as high. This can be caused by reticulocytosis or cold-agglutinins

45
Q

Patients with pernicious anaemia can appear mildly jaundiced due to…

A

Intramedullary haemolysis

46
Q

What is ineffective erythropoiesis?

A

Red cells die prematurely in the marrow
Haemoglobin and lactate dehydrogenase (LDH) are released from dead red cells
Haemoglobin converted to bilirubin

47
Q

Pancytopenia can complicate..

A

Megaloblastic anaemia

48
Q

Nuclear maturation defects can affect..

A

Multiple lineages

49
Q
A

3MB Haematology (23 decks)

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