Classification of Anaemia

1. CLASSIFICATION OF ANAEMIA:
Macrocytic Anaemia

2. Macrocytic anaemias
Macrocytic anaemia
(MCV>RR)
Megaloblastic Non-megaloblastic
anaemia anaemia
-Oval macrocytes Round macrocytes
-Hypersegmented
neutrophils
-Liver disease
-B12 deficiency -Alcoholism
-Pernicious anaemia -MDS
-Folate deficiency -Drug induced
-B12/Folate -Reticulocytosis
-Others
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3. Vitamin B12 (Cobalamin)
• Synthesized by some microorganisms
• Food that contains cobalamin is from animal
origin
• Average daily diet contains ~ 5-30ug
– 1-5ug is absorbed
• ~2-5mg are stored
– Liver
– Kidneys
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4. www.uq.edu.au/vdu/HDUAn
aemiaMegaloblastic.htm
B12 absorption Accessed 14.04.08
Mouth:Unbound B12 Stomach:
may be absorbed
Protein-bound B12
detaches
R-Protein picks up B12
IF secreted
Upper small intestine:
Liver:
R-protein releases B12. IF
B12 is stored and picks up B12
released into small
intestine via the bile Lower small intestine:
IF-B12 attaches to receptor
Some unbound B12 absorbed
Blood: Intestinal cells:
Transcobalamin II B12 attaches to
carries B12 to cells OR transcobalamin II
to liver for storage
(transcobalamin III)
http://www.veganhealth.org/b12/images/b12absorption1.gif Accessed 14.04.08
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5. Transcobalamins
• Transcobalamin II
– Synthesised by the liver, vascular endothelium, enterocytes, macrophages and
fibroblast
– Half – life ~ 90min
– Mainly circulates as apoTCII
– Carries 6-25% of B12 & takes it to the tissues
– Binds to TC II-R and is internalised by receptor-mediated endocytosis & is not recycled
• Transcobalamin I and III (TCI & TCIII)
– Synthesised in the liver
– 75% of plasma B12 binds to TCI
• Storage protein for B12
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6. B12 function
http://emedicine.medscape.com/article/1152670-overview Accessed180309

7. B12 function
http://emedicine.medscape.com/article/1152670-media Accessed 140309 7

8. B12 deficiency
• Folate trapping
– Abnormal DNA synthesis
• Homocysteine
– Plasma toxicity
– Deterioration of inner lining of arteries and veins
– => leads to risk for CHD, PVD and stroke
• ? of S-adenosylmethionine (SAM)
– Shown to help treat depression
– ?Abnormal neuronal conduction
• Leads to development of methylmalonic aciduria
– Associated with neurological symptoms and learning
deficiencies
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9. Causes of B12 deficiency
Inadequate
Increased need
intake
Malabsorption
B12 deficiency
Competition
Impaired for B12
absorption
Gastrectomy
Lack of IF Failure to separate
from haptocorrin
Pernicious
anaemia 9

10. Pernicious anaemia
 Mean age of onset is 60 years
 Impaired absorption of B12 due to a lack of IF
 Autoimmune disorder
 ? genetic predisposition
 Lymphocyte mediated destruction of parietal cells =>
IF not secreted
 Antibodies block IF action
 Blocking Abs detectable in serum
 Leads to development of atrophic gastritis
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11. Folate
• Normal daily intake = 650 μg
• Amount lost = 13 μg (urine)
• Daily requirements = 200 μg
• Storage = 5mg
• Food sources include green leafy vegetables
, bananas, strawberries, nuts, liver, yeast
• Lots of food has been fortified with folate
• Vulnerable to heat and dissolves in water - so cooking can reduce the
levels
Research indicates that increased folate intake can prevent
seven out of 10 births of babies affected by a neural tube defect
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12. Folate
• Before folate can be used, the following
reactions occur:
Dihydrofolate Tetrahydrofolate
Folate FH4
FH2
Dihydrofolate
reductase
• Occurs as conjugate of one or multiple
glutamic acids
– Folic monoglutamates & polyglutamates exist
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13. Folate absorption
1. Unconjugated
or conjugated 3. Monoglutamates
dietary folate transported across
2. All intestinal epithelium
polyglutamates
are deconjugated
4. FH4 formation in
intestinal epithelium
6. Polyglutamates 5. Monoglutamates
formation circulate in blood
inside cells & are transported
into cells
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14. Folate function
 The principal function of
folate coenzymes is to
accept or donate one-
carbon units in key
metabolic pathways
 Folate-requiring reactions
include:
 those involved in phases
of amino acid
metabolism
 purine and pyrimidine
synthesis
 formation of the primary
methylating agent, S-
adenosylmethionine
(SAM)
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1519435&blobtype=pdf Accessed 150408
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15. Causes of folate deficiency
Increased need
Inadequate
intake
Folate
deficiency
Impaired
absorption
Excessive loss
Impaired
utilisation
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16. Symptoms of B12 & folate deficiency
 Anaemia  Neurologic symptoms
 Weakness  May appear before anaemia
 Fatigue  Memory loss
 SOB  Loss of balance
 Pallor – may be severe  Numbness in toes and fingers
 Depression
 Loss of epithelium  “Megaloblastic madness”
 Glossitis
 Gastritis  Jaundice
 Constipation  Weight loss
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17. Megaloblastic anaemia
FBE Results:
 Hb/RCC/Hct
 MCV
 RDW
 Plt/WCC
 =>Pancytopenia may develop
 Oval macrocytes
 Hypersegmented neutrophils
 No polychromasia
 Poikilocytosis, tear drops
 In severe megaloblastic anaemia
 Basophilic stippling
 Howell Jolly bodies
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18. Megaloblastic anaemia
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19. Megaloblastic anaemia
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20. Bone Marrow
• Shows megaloblastic changes
• Nuclear-cytoplasmic asynchrony
• Hypercellular
• M:E = 1:1
– Intramedullary haemolysis due to ineffective erythropoiesis
• Giant WBC precursors
– Metamyelocytes and bands
• Megakaryocytes vary
Is NOT performed unless there is a suspicion of megaloblastic
anaemia in a child
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21. Diagnosis of B12/Folate deficiency
• Bilirubin
• LDH Evidence of haemolysis
• Haptoglobin
• Homocystine
• IF of parietal cell antibodies
• ? Methylmalonic acid – serum or urine
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22. Treatment of megaloblastic anaemia
• Directed at specific vitamin deficiency
– Treating B12 deficient patient with folate may increase
neurological symptoms
• Folate and B12 tablets administered orally
– Iron may be supplemented
• B12 may be administered intramuscularly
– No need for IF
– Lifelong administration for PA patients
• Sublingual or nasal B12 available
– Expensive

23. Liver disease
• Anaemia
– Macrocytes (round) & target cells
• Due to abnormalities of RBC membrane lipids
– anisocytosis & poikilocytosis than in megaloblastic anaemia
– reticulocytes
• Thrombocytopenia
– Often mild and due to hypersplenism
– If due to alcohol
• May have abnormal platelet aggregation and secretion
• Direct marrow suppression
• Coagulopathy
– Lack or malabsorption of VitK
– Decreased synthesis of coagulation proteins
– Synthesis of abnormal proteins
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24. Alcoholic liver disease
• The effects of alcohol may be:
– Direct – seen in the BM
– Indirect – liver disease or due to nutritional abnormalities
• Anaemia (? haemolytic) + impaired RC production
• Leucopenia + neutropenia
– Suppression of growth factors
– Splenomegaly
• Concurrent infection/inflammation that may give rise to ACD
– Abnormal N function and decrease Ab production
• Thrombocytopenia
– Ineffective thrombopoiesis
• May lead to development of (reversible) sideroblastic anaemia
• Folate and iron deficiencies are common
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25. Liver disease
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26. Diagnosis of liver disease
• Abnormal LFT
• Coagulation
– PT
• Prolonged even in mild liver disease
• fVII and fX particularly affected
– APTT
– Fibrinogen
• May be elevated in early liver disease (acute phase reactant)
• May be structurally abnormal
– Folate and Iron storage may be low
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27. Learning objectives
• Be able to describe different types of macrocytic
anaemias and their causes
• Understand the function and metabolism of B12 and
folate and the causes and impact of deficiency in either
one
• Show an understanding of tests and expected results
that may be performed in order to diagnose B12/Folate
deficiency
• Be able to explain other causes of macrocytosis (liver
disease, MDS and drug induced)
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28. Study Questions
• What are the expected results in a patient
with megaloblastic anaemia and why?
• Why do we need B12 and Folate and what
effect will the deficiency of either one have?
• What is pernicious anaemia, what is its cause
and how is it diagnosed?
• How would you diagnose liver disease?
• List the causes of macrocytosis and briefly
explain the pathophysiology of each.
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