Microcytic Anaemia Flashcards
What is microcytic anaemia?
low MCV indicating small RBCs
What are the causes of microcytic anaemia?
TAILS
T – Thalassaemia A – Anaemia of chronic disease I – Iron deficiency anaemia L – Lead poisoning S – Sideroblastic anaemia (congenital)
a history of a normal haemoglobin level associated with a microcytosis, In patients not at risk of thalassaemia, consider what diagnosis?
polycythaemia rubra vera which may cause an iron-deficiency secondary to bleeding.
New onset microcytic anaemia in elderly patients is a normal sequelae in ageing
FALSE
New onset microcytic anaemia in elderly patients should be urgently investigated to exclude underlying malignancy.
in beta-thalassaemia minor the microcytosis is often disproportionate to the anaemia
true
What is the most common anaemia worldwide?
Iron deficiency anaemia
Pathophysiology of Iron deficiency anaemia
Iron is needed to make the haemoglobin in red blood cells, therefore a deficiency of iron leads to a reduction in red blood cells/haemoglobin i.e. anaemia.
Iron deficiency anaemia has the highest incidence amongst
preschool-age children.
What are the main causes of iron deficency anaemia
excessive blood loss
inadequate dietary intake
poor intestinal absorption
increased iron requirements.
What are some common causes of non-acute excessive blood loss?
blood loss due to menorrhagia is the most common cause in pre-menopausal women
gastrointestinal bleeding is the most common cause in men and post-menopausal women.
What should you always suspect in someone with gi bleeding
colon cancer
vegans always get iron def anemia
dark green leafy vegetables are another good source of iron, therefore people who don’t eat meat can still receive enough iron through purely dietary sources
Who has increased iron requirements?
children have increased iron demands during periods of rapid growth
Pregnancy as the baby will receive their iron supply from the mother
Also an increase in plasma volume during pregnancy causes iron deficiency anaemia through dilution i.e. the proportion of fluid in comparison to red blood cells increases.
What are symptoms of iron defiency anaemia?
Fatigue
Shortness of breath on exertion
Palpitations
Pallor
What signs are pathonogmonic of iron defiency anaemia?
Nail changes: this includes koilonychia (spoon-shaped nails) Hair loss Atrophic glossitis Post-cricoid webs Angular stomatitis
What should you ask about in a hx for iron defiency anaemia?
changes in diet medication history menstrual history weight loss change in bowel habit
Full blood count (FBC) demonstrates what in iron defiency anaemia?
hypochromic microcytic anaemia
Iron studies will show what in iron defiency anaemia?
Serum ferritin this will likely be low
Total iron-binding capacity (TIBC)/transferrin this will be high
transferrin saturation will however be low
Why is serum ferritin low in iron defiency anaemia?
serum ferritin correlates with iron stores
Why might serum ferritin be raised in iron defiency anaemia?
ferritin can be raised during states of inflammation
For patients with co-occurring inflammatory disease, other iron studies can be performed.
What does a high TIBC/transferrin reflect?
low iron stores
What will blood film show in iron defiency anaemia?
anisopoikilocytosis (red blood cells of different sizes and shapes)
target cells
‘pencil’ poikilocytes
Endoscopy is routinely done in iron-deficiency anaemia
false
males and post-menopausal females who present with unexplained iron-deficiency anaemia should be considered
In iron defieincy canaemia who should be refered to a GI specialist? How soon?
Post-menopausal women with a haemoglobin level ≤10
men with a haemoglobin level ≤11
within 2 weeks.
The underlying cause of the iron-deficiency anaemia must be identified and managed. It is particularly important that malignancy has been excluded by taking an adequate history and appropriate investigations if warranted
true
Once other causes ruled out and managed, how do you manage iron defiency anaemia?
Oral ferrous sulfate
Iron-rich diet: this includes dark-green leafy vegetables, meat, iron-fortified bread
How long should patients be on Oral ferrous sulfate?
3 months after the iron deficiency has been corrected in order to replenish iron stores
Common side effects of iron supplementation include?
nausea
abdominal pain
constipation
diarrhoea
questions giving a combination of abdominal pain and neurological signs, consider what diagnosis?
Along with acute intermittent porphyria, lead poisoning
Lead poisoning results in defective what?
defective ferrochelatase and ALA dehydratase function.
Symptoms of lead poisioning?
abdominal pain peripheral neuropathy (mainly motor) fatigue constipation blue lines on gum margin (only 20% of adult patients, very rare in children)
Diagnosis of lead poisoning?
the blood lead level is usually used for diagnosis. Levels greater than 10 mcg/dl are considered significant
FBC in lead poisoning?
microcytic anaemia
Blood film in lead poisoning?
basophilic stippling and clover-leaf morphology
In lead poisoning raised serum and urine levels of delta aminolaevulinic acid may be seen making it sometimes difficult to differentiate from what?
acute intermittent porphyria
What porphyrin is increased in lead posioning?
urinary coproporphyrin is also increased (urinary porphobilinogen and uroporphyrin levels are normal to slightly increased)
How can lead poisoning affect children?
lead can accumulate in the metaphysis of the bones although x-rays are not part of the standard work-up
What agents are used to manage lead poisoning?
chelating agents
What medications are used in lead poisoning?
dimercaptosuccinic acid (DMSA)
D-penicillamine
EDTA
dimercaprol
What is sideroblastic anaemia?
condition where red cells fail to completely form haem
Where is haem usually formed
biosynthesis takes place partly in the mitochondrion
What is a sideroblast
deposits of iron in the mitochondria that form a ring around the nucleus
sideroblastic anaemia is only congenital
false It may be congenital or acquired
What is a congenital cause of sideroblastic anaemia?
delta-aminolevulinate synthase-2 deficiency
What is a acquired cause of sideroblastic anaemia?
myelodysplasia
alcohol
lead
anti-TB medications
What would blood film show in sideroblastic anaemia?
hypochromic microcytic anaemia (more so in congenital)
What would bone marrow show in sideroblastic anaemia?
sideroblasts and increased iron stores
Management of sideroblastic anaemia?
supportive
treat any underlying cause
pyridoxine may help
What is a thalassaemia?
genetic defect in the protein chains that make up haemoglobin.
What is normal haemoglobin composed of?
2 alpha and 2 beta-globin chains.
Alpha-thalassaemia is due to a deficiency of
alpha chains in haemoglobin
Thalassaemias usually inherited how
autosomal recssive
2 separate alpha-globulin genes are located on which chromosome
16
In alpha thalassemia, clinical severity depends on twhat
number of alpha globulin alleles affected
Alpha thalassemia: If 1 or 2 alpha globulin alleles are affected then?
blood picture would be hypochromic and microcytic
but the Hb level would be typically normal
Alpha thalassemia: If are 3 alpha globulin alleles are affected results in?
hypochromic microcytic anaemia with splenomegaly
Alpha thalassemia: If all 4 alpha globulin alleles are affected what do you call it
homozygote
Alpha thalassemia: If all 4 alpha globulin alleles are affected?
death in utero (hydrops fetalis, Bart’s hydrops)
What is Hb H disease?
Alpha thalassemia - If are 3 alpha globulin alleles are affected
What is Beta-thalassaemia trait?
eta-thalassaemia trait is an autosomal recessive condition characterised by a mild hypochromic, microcytic anaemia
How does Beta-thalassaemia trait present?
It is usually asymptomatic
In Beta-thalassaemia trait microcytosis is characteristically disproportionate to the anaemia
true
What is raised In Beta-thalassaemia trait
HbA2 raised (> 3.5%)
Absence of beta chains is usally due to problems on which chromosome?
11
What is Beta-thalassaemia major?
absence of beta chains
How does Beta-thalassaemia major present?
presents in first year of life with failure to thrive and hepatosplenomegaly
What would investigations for Beta-thalassaemia major show?
microcytic anaemia
HbA2 & HbF raised
HbA absent
How do you manage Beta-thalassaemia major ?
repeated transfusion → iron overload
s/c infusion of desferrioxamine
Compare Iron deficiency anaemia & Anaemia of chronic disease
Serum Iron is lower in IRDA <8 AOCD <15 - both low however.
TIBC is high in IRDA & low in AOCD
Transferiin saturation low in both
Ferritin low in IDA & high in AOCD
