Anaemias: the basics! Flashcards
What are the two main sub-types of Anaemia?
Destructive and Underproductive
What are the baseline reason for Destructive/Haemolytic Anaemia?
The two sub-groups are?
There is damage to the RBC which causes increased clearance, eventually accompanied by a compensatory effort by the body.
- Intracorpuscular: damage from within the cell
- Extracorpuscular: damage from outside the cell
What are the types of intrinsic/intracorpuscular Haemolytic anaemia are there?
- Hb-opathies
- sickle-cell, Thalassemia
- Membranopathies
- Hereditary spherocytosis
- Hereditary Elliptocytosis
- Enzymopathies
- G6PD deficiency: Hinnes bodys on smear!
What are the types of Extracorpuscular Haemolytic anaemia?
- IMHA
- where the body forms antibodies to antigens on the RBC surface, causing immune mediated RBC destruction
- Can occur with Penicillin
- Coombs test part of diagnosis
- MAHA
- when clots form within the BV, causing RBC shearage and Shistocytes on a smear
- Thrombotic Thrombocytopenic Purpura (TTP) and DIC cause
- Malaria: the Protozyte live in the RBC, if enough are killed → anaemia
- Blood Transfusions
- Fetal Rh Incompatibility
- if mum is Rh - and baby Rh +, she will form Rh + antibodies against, so if any proceeding pregnancies are Rh+ baby will be attacked → Haemolytic Disease Newborn
How will a patient will with haemolytic anaemia present?
All:
- High bilirubin: due to RBC destruction
- Jaundice and dark brown urine
- Decreased Haptoglobin: Some excess haemaglobin binds to haptoglobin to reduce Oxidative damage
- Spleenomegaly
- High Reticulocytes
- Coombs: IMHA
- Spherocytes, Elliptocytes or Shistocytes on smear
What are the subgroups of Underproductive anaemia, how are they defined and what are the common reasons for them
- Microcytic (MCV <80)
- Iron deficiency
- Thallessemia (globin defect)
- Chronic Disease
- Lead poisoning
- Macrocytic (MCV >100)
- B12 or folate deficiency = megaloblastic
- Liver or alcohol issues = normoblastic
- Normocytic (MCV 80-100)
- blood loss
- BM failure
Why do we get microcytic anaemia and what causes it?
Microcytic anaemia is due to a deficiency Hemeglobin, with either the heme or globin aspect being impaired
As theres not enough in each cell they undergo another division!
Heme:
- Iron: Iron deficiency or anaemia of chronic disease
- Protoporphyrin: Sideroblastic anaemia
Globin
- à globin
- ß globin: Thalassemias
4 Causes of iron deficient anaemia?
- Decreased intake
- often in infants
- Increased demand
- adolesants + pregnant woman
- Decreased absorption
- decreased stomach acid: taking PPI or had a gastrectomy
- issue in duodenum: coeliac disease
- Increased loss**
- menorrhagia
- peptic ulcer disease
- colorectal cancer
- hook worm
Where is iron absorbed? How does it travel in body?
- At the duodenum (requires stomach acid).
- Travels in blood via transferrin.
- Mainly stored in liver macrophages bound to ferritin.
It cannot travel alone, as it will produce free radicals and cause damage
What does % transferrin saturation mean?
How many sites on transferrin are occupied by iron.
Normal 33%
Lower in iron deficient anaemia
What does total iron binding capacity?
Reflects the total amount of transferrin, decreases with the amount of transferrin in the body, which should increase as a compensatory response to iron deficieny.
Why would you give a patient RhoGAM?
- prevent Rh isoimmunization in mothers who are Rh negative during pregnancy
- to treat idiopathic thrombocytopenic purpura (ITP) in people who are Rh positive
What is hepcidin
Chain of amino acids made in liver that regulates iron, by decreasing serum iron.
It does this by
- blocking the ferroportin channels in the duodenum, stopping iron absorption
- inhibits recyling of iron being stored in liver
Whats the pathophysiology of anaemia of chronic disease
Any source of inflammation in the body → increased cytokines → increased Hepcidin → decreased iron absorption → decreased hemeglobin → anaemia
This occurs as a protective measure as bacteria feed off iron!
Macrocytic megaloblastic anaemia is due to a DNA problem, how does this work?
Due to a B12 or Folate (THF in the body) are both required to convert
homocystiene → methionine
THF is also converted to purines that make up DNA
