Lecture 5: Clinical approach to patient with anaemia Flashcards
Define anaemia, its features and some factors that influence its levels over life:
Heamoglobin lower than normal for age and sex of patient (NOT RBC COUNT)
Features: Pallor, Tiredness, SOB, enhanced CV and resp symptoms
NB: Hb high at birth then falls 3m-1y
- HB increases with age, falling in later years
- Hb in M > F
What is a heamacrit?
% RBC of total volume of blood
Packed cell volume / PCV is synonymous
How is anaemia classified?
- Basic mechanism / physiological approach.
i. e Impaired production vs blood loss / haemolysis - Morphological approach
i. e based on the appearance of the red cells
What can the basic mechanism approach be broken down into?
Ineffective production vs impaired red cell survival
What are the causes of impaired red cell production?
- Deficiency of substances essential for red cell production i.e iron, vitmain B12, folate
- Genetic defects in RBC production
i. e thalassemia - Failure of bone marrow
i. e infiltration i.e leukemia, irradiation or drug damage
What impairs RBC survival?
Blood loss i.e usually acute; treuma or surgery
Haemolysis
- Shortened survival of the red cell
What indicates haemolysis?
Increased EPO
Increased billirubin (non-conjugated, possibile yellow sclera)
Increased reticulocytes
Pale conjuctiva
Whats the morphological approach to anaemia?
Morphological approach: Uses mean cell volume, average cell Hb concentration and blood film comment
What are the notable morphological anaemias?
- Microcytic hypochromic anaemia (MCV <76)
- Normochromic normocytic anaemia (MCV 76 - 96)
- Macrocytic anaemia (MCV > 96)
What are some red cell values from a lab test?
Heamoglobin : g/L
Red cell count
Heamatocrit or packed cell volume (%)
Red cell absolute values:
- MCV
- Mean cell HB (MCH)
- Mean cell Hb concentration (MCHC)
What are some other helpful investigations of anaemia?
- WBC and platelet count (leukemia)
- Reticulocyte count
- Examination of blood film
- Bone marrow examination
What can cause microcytic hypochromic anaemia?
Iron deficiency
Chronic illness - Iron block
Genetic - Thalassaemia
i. e decreased heame production
appear: Smaller, less pink, tear shaped, hypochromic
How is iron deficiency diagnosed?
Measure: Serum iron (low), iron binding capacity (transferrin, high b/c trying to get iron from gut), and iron saturation (low)
Measure: Serum ferritin (soluble iron storage, decreased)
Rarely examine iron stores in bone marrow
What sort of protein is serum ferritin?
Acute phase protein and can increase in sickness
Is iron deficiency anaemia enough?
No, iron deficiency is NOT A DIAGNOSIS, must identify the cause of deficiency
Anaemia occurs late in iron deficiency
What are the causes of iron deficiency?
Diet - Vegetarian
Malabsorption - Proximal small bowel
Increased demands - Pregnancy
Chronic blood loss - GI or GU tract
Who are most likely predisposed to iron deficiency/
Children - Low dietary intake
Pre-menopausal females - Imbalance between diet intake and menstural loss
Males and post menopausal women - occult blood loss
Whats the treatment for iron deficiency?
Iron replacement therapy
- Oral tablets i.e ferrograd
- IV infusion i.e ferric carboxymaltose
Hb conc. increases ~20
What is the profile of chronic inflammation anaemia?
“Iron block”
- Normochromic to mildly hypochromic
- Mild anaemia
Iron studies:
- Normal to raised ferritin
- Low normal Fe
- Low normal TIBC
- Normal saturation
What probably causes the iron block?
Hepcidin synthesis in the liver because of inflammation
What is thalassemia?
One or both alpha or beta chains reduced / absent
Recessive, heterozygous
Heterozygote : Mild anaemia
Homozygote: Severe anaemia (requires transfusions)
Diagnosied through gene panel
What causes a macrocytic anaemia?
B12 or folate deficiency, (Megablastic anaemia (descriptive term)
Liver disease
Also:
- Alcohol
- Primary bone marrow disorder
- Hypothyroidism
In macrocytic anaemia is the chromatin affected?
No, no hyper ot hypochromic
Why does the anaemia result in B12/folate deficiency?
Because impaired DNA synthesis results in abnormal maturation
How else can B12/Folate deficiency affect all bloods?
- Impaired DNA synthesis
- May affect all cell lineages if severe
How is B12/folate deficiency diagnosed?
Measure serum B12 and folate leves
Need to determine cause
RBC most sensitive
What can cause low B12 levels?
Diet - Vegans
Malabsorption
- Gastrectomy
- Immune i.e pernicious anaemia
- Terminal ilium disease
NB: Body has stores for 3-4 years
What can cause low folate levels?
Diet i.e lack of vegetables
Malabsorption i.e Coeliac disease
Increased demands i.e pregnancy, haemolytic anaemia
What is haemolytic anaemia:
Shortened survival of red cells
Intrinsic defect in the red cell i.e inherited defect in red cell membrane
Environmental or extrinsic i.e autoimmune destruction of red cell
What are the clinical features of heamolytic anaemia?
Increased red cell destruction: Anaemia, Mild jaundice, increased spleen size
Increased RBC production: Raised reticulocyte count
Key points:
Define anaemia
Classification/investigation of anaemia
Pathologic: Production vs loss
Morphology: Microcytic vs macrocytic
Microcytic: Iron deficient
Macrocytic: B12 or folate deficiency
