microcytic anaemia

Question 1

definition of microcytic anaemia

Answer 1

Anaemia associated with low MCV (<80 fl).

Question 2

aetiology of microcytic anaemia

Answer 2

iron deficiency commonest cause

anaemia of chronic disease - often normocytic, can be monocytic

thalassaemia

sideroblastic anaemia

lead poisoning (eg in scrap metal or smeltering workers) - interferes with globin and haem synthesis

Question 3

aetiology of IDA

Answer 3

blood loss eg GIT, urogenital tract, hookworm infection, menorrhagia

reduced absorption - small bowel disease, post-gastrectomy, coelic (refractory IDA)

increased demand - pregnancy, growth

reduced intake - vegans, poor diet or poverty in children

Question 4

sideroblastic anaemia

Answer 4

abnormality of haem synth

can be inherited (x-linked)

secondary to alcohol, drugs (eg isoniazid, chloramphenicol), lead, myelodysplasia/myeloproliferation

chemo

irradiation

alcohol

NOT IRON DEFICIENT

Question 5

epidemiology of microcytic anaemia

Answer 5

Iron-deficiency anaemia is the commonest form of anaemia worldwide.

Question 6

sx of microcytic anaemia

Answer 6

tiredness

lethargy

malaise

dyspnoea

pallor

exacerbation of pre-existing angina or intermittent claudication

FH of causitive disease

Question 7

lead poisening sx

Answer 7

anorexia

nausea

vomiting

abdominal pain

constipation

peripheral nerve lesions

Question 8

signs of microcytic anaemia

Answer 8

signs of anaemia

• pallor of skin and mucous membranes
• brittle nails and hair
• if long standing and severe - koilonychia

glossitis - atrophy of tongue papillae

cheilitis - angular stomatitis

signs of thalassaemia

signs of lead poisoning

Question 9

signs of lead poisoning

Answer 9

blue gumline

peripheral nerve lesions - wrist/foot drop

encephalopathy

convulsions

reduced consciousness

Question 10

Ix for microcytic anaemia

Answer 10

blood

blood film

Hb electrophoresis

Question 11

blood results if microcytic anaemia

Answer 11

FBV - low Hb, low MCV, reticulocytes

serum iron - low in ID

iron binding capacity - increased in ID

serum ferritin - low in ID

serum led - if poisoning suspected

in thalassaemia and sideroblastic anaemia - hogh serum iron and ferritin and low total iron binding capacity

Question 12

blood film in IDA

Answer 12

microcytic, hypochromic (central pallor >1/3 cell size),

anisocytosis (variable cell size)

poikilocytosis (variable cell shape)

Question 13

blood film in sideroblastic anaemia

Answer 13

dimorphic blood film with a population of hypochromic microcytic cells

Question 14

blood film for lead poisoning

Answer 14

basophilic stippling - coarse dots represent condensed RNA in cytoplasm

Question 15

Hb electrophoresis for microcytic anaemia

Answer 15

for Hb variants for thalassaemias

sideroblastic anaemia

• ring sideroblasts in bone marrow, iron deposited in perinuclear mitochondria of erythroblasts, stain blue-green with Perls’ stain

Question 16

Ix if iron-deficiency anaemia in>40 years and post-menopausal women

Answer 16

upper GI endoscopy

colonoscopy

investigations for haematuria

all should be considered if no obvious cause of blood loss

Question 17

Mx for IDA

Answer 17

oral iron supplements eg 200mg ferrous sulphate tablets containing 65mg of elemental iron, 2 or 3x daily taken with food

SE - nausea, abdo discomfort, diarrhoea/constipation, black stools

If oral iron intolerance or malabsorption or functional iron deficiency in chronic renal failure where inadequate mobilisation of iron stores in response to erythropoetin therapy - consider parenteral iron supplements (beware risk of anaphylaxis).

monitor Hb and MCV, aiming for Hb rise of 1g/dL/week. Modest reticulocytosis

continue for at least 3mo

Question 18

Mx of sideroblastic anaemia

Answer 18

treat the cause - stop causative drug

pyridoxine can be used in inherited forms

if no response - blood transfusion and iron chelation

Question 19

Mx of lead poisoning

Answer 19

remove source

dimercaprol

D-penicillamine

Ca2+ EDTA

Question 20

complications of microcytic anaemia

Answer 20

high output cardiac failure

complications of the cause

Question 21

prognosis of microcytic anaemai

Answer 21

depends on cause

Question 22

signs of IDA

Answer 22

koilonychia

atrophic glossitis

angular cheilosis

post-cricoid webs (Plummer-Vinson syndrome)

Question 23

Ix results for IDA

Answer 23

blood film:

• microcytic
• hypochromic anaemia
• anisocytosis
• poikilocytosis

blood

• low MCV, MCH< MCHC
• low ferritin
• low iron
• high TIBC (transferrin)

check coelic serology - if -ve refer men adn women not menstruating to gastroscopy and colonscopy

stool microscopy for ova if relevant travel history

Question 24

ferritin

Answer 24

acute phase protein

increases with inflammation eg infection and malignancy

Question 25

anaemia of chronic disease

Answer 25

most common anaemia in hospital patients arises from 3 problems - hepcidin plays a role (stops iron uptake and transport, and increases storage) * poor use of iron in erythropoiesis * cytokine-induced shortening of RBC survival * reduced production of and response to erythropoietin

Question 26

aetiology of anaemia of chronic disease

Answer 26

chronic infection vasculitis rheumatoid malignancy renal failure

Question 27

Ix results for anaemia of chronic disease

Answer 27

ferritin normal or high in mild normocytic or microcytic anaemia check blood film, B12, folate, TSH and test for haemolysis low iron low TIBC high ferritin

Question 28

Mx of anaemia of chronic disease

Answer 28

treat underlying disease erythropoietin - SE - flu like sx, HTN, mild rise in platelet count and thromboembolism effective in improving the QOL in malignant disease IV iron can overcome functional iron deficiency

Question 29

pathology of sideroblastic anaemia

Answer 29

ineffective erythropoiesis = increased iron absorption, iron loading in marrow +- haemosiderosis (endocrine, liver and heart damage due to iron deposition)

Question 30

Ix results fo sideroblastic anaemia

Answer 30

high ferritin hypochromic blood film disease-defining sideroblasts in marrow

Question 31

interpreting iron studies

Answer 31