Anaemias Flashcards
Numerical definition of anaemia in men and women
Men = Hb under 135g/L, Women = Hb under 115g/L
Causes of anaemia (3 groups)
Reduced production of RBCs, increased loss of RBCs (haemolytic anaemias), increased plasma volume
4 causes of Microcytic Anaemias
FAST: Fe Deficiency anaemia, Anaemia of chronic disease, Sideroblastic anaemia, Thalassaemia (in the absence of anaemia)
7 causes of Normocytic Anaemias
Acute blood loss, ACD, Bone Marrow Failure, Renal failure, Hypothyroidism, Haemolysis, Pregnancy
7 causes of Macrocytic Anaemias
FATRBC: Foetus (Pregnancy), Antifolates (e.g. Phenytoin), Thyroid (hypothyroidism), Reticulocytosis, B12 or folate deficiency, Cirrhosis (Alcohol xs or liver disease), Myelodysplastic syndromes
Clinical signs of Iron Deficiency Anaemia
Hands: koilonychia, brittle nails
Face: atrophic glossitis, angular cheilosis, brittle hair
Chest: ejection systolic murmur ( due to turbulent flow in severe Anaemia)
Plummer Vinson syndrome = IDA + post-cricoid webs +
Typical IDA Blood Film
Microcytic, hypochromic, anisocytosis, poikilocytosis, pencil cells
Causes of IDA
Blood Loss: GI loss
Increased Utilisation: Pregnancy, Growth
Decreased Intake: Prematurity, Infants/children/elderly
Decreased Absorption: Coeliac, Post-gastric surgery
Intravascular haemolysis: Microaniopathic, Haemolytic anaemia, PNH
Treatment of IDA
Treat the cause! Oral iron (SE: nausea, abdominal discomfort, diarrhea/constipation, black stools)
Explain the mechanism behind Anaemia of Chronic Disease (How does chronic disease causes anaemia?)
Cytokine driven inhibition of RBC production:
-Inflammatory markers (IFN, TNF, IL1) reduce EPO receptor production by kidneys.
IL6 and LPS stimulate the liver to make hepcidin which decreased iron absorption from gut by inhibiting transferrin, and also causes iron accumulation in macrophages
What are the causes of ACD?
Chronic Infection (TB, Osteomyelitis etc.), Vasculitis, Rheumatoid Arthritis, Malignancy
Is the ferritin level (intracellular protein iron store) low or high in ACD and why?
Is it low or high in IDA?
ACD: high, because Fe is sequestered into macrophages to deprive invading bacteria of Fe
IDA: low
Mechanism underlying Sideroblastic Anaemia
Ineffective erythropoiesis: Iron loading (bone marrow) causing haemosiderosis. Can lead to endocrine, liver, and cardiac damage due to iron deposition
Causes of Sideroblastic anaemia
Myelodysplastic disorders, following chemotherapy, irradiation, alcohol XS, lead XS, anti-TB drugs, myeloproliferative disease
How is Sideroblastic Anaemia diagnosed?
Ring sideroblasts seen in the marrow (erythroid precursors with iron deposited in mitochondria in a ring around the nucleus)
Treatment of Sideroblastic anaemia
Remove the cause and Pyridoxine (vit B6 promotes RBC production)
Will Iron, TIBC and Ferritin be high, normal, or low in:
Iron Deficiency Anaemia?
Iron - Low
TIBC - High
Ferritin - Low
What does a megaloblastic blood film look like?
Hypersegmented polymorphs, leucopenia, macrocytosis, anaemia, thrombocytopenia
What are the megaloblastic causes of macrocytosis?
B12 deficiency, folate deficiency, cytotoxic drugs
What are the non megaloblastic causes of macrocytosis?
Alcohol (most common cause of macrocytosis without anaemia), reticulocytosis, liver disease, hypothyroidism, pregnancy.
What haematolgical diseases are associated with a macrocytic blood film?
Myelodysplasia, myeloma, myeloproliferative disorders, aplastic anaemia`
Why might someone have a Vit B12 deficiency?
- Dietary (found in meat and dairy products)
- Malabsorption in stomach: IF is produced by gastric parietal cells and needed for B12 to be absorbed later, could be lacking due to pernicious anaemia or post gastrectomy
- Malabsorption in terminal ileum: ileal resection, crohn’s disase, bacgterial overgrowth, tropical sprue and tapeworms
What are the clinical features of B12 deficiency?
Glossitis, angular cheilosis, irritability, depression, psychosis, dementia, paraesthesiae, peripheral neuropathy (loss of vibration and proprioception first, absent ankle reflex, spastic paraperesis, SACD of spinal cord)
What is pernicious anaemia?
Autoimmune atrophic gastritis: achlorhydria and lack of gastric intrinsic factor.
Most common cause of macrocytic anaemia in Western countries
What are the specific tests for Pernicious anaemia?
Parietal cell antibodies (90%), IF antibodies (50%), Schilling test (outdated)
What is the treatment for Vit B12 deficiency?
Replenish stores with IM hydroxocobalamin
What are the causes of folate deficiency?
Poor diet
Increased demand: pregnancy or increased cell turnover (haemolysis, malignancy, inflammatory disease, renal dialysis)
Malabsorption: coeliac disease, tropical sprue
Drugs: alcohol, anti-epileptics, methotrexate, trimethoprim
When should folic acid not be given in a macrocytic anaemia?
When the cause of anaemia is not known, as folic acid will exacerbate the neuropathy of B12 deficiency
Causes of Inherited Haemolytic Anaemias
Membrane defect: hereditary spherocytosis, hereditary elliptocytosis
Enzyme defect: G6PD deficiency, PKD
Haemoglobinopathies: Sickle cell disease, thalassaemias
Causes of acquired Haemolytic anaemias
Immune: Autoimmune, alloimmune (haemolytic transfusion reactions
Non-immune: Mechanical (metal valves, trauma), PNH, MAHA, Infections, Drugs