Theme 7 Haemotology: Common causes of anaemia and thrombocytopenia Flashcards
(31 cards)
Give all the causes of anaemia (other than blood loss)
- haematinic deficiencies (iron, folate and B12)
- secondary to chronic disease
- haemolysis - red cell lifespan reduced
- alcohol, drugs, toxins
- renal impairment
- primary haematological/ marrow disease
If red cells are macrocytic, there is a raised MCV. What are the causes of this?
- B12, folate
- marrow damage (alcohol, drugs and marrow disease)
- haemolysis
If red cells are normocytic, the MCV is the same. What are the causes of this?
anaemia of chronic disease/ inflammatory
If red cells are microcytic, the MCV is reduced. What are thhe causes of this?
- iron deficiencies
- haemaglobin disorders
Explain how iron concentration is balanced
- there is no excretion and limited absorption
- controlled at the level of the gut mucosa
- most iron is thus recycled
- absorbed in duodenum
- stored in ferritin
How do we establish a patient has low iron?
- FBC and film
- ferritin –> if ferritin is low = iron deficiency
- % hypochromic cells
What are the main causes of iron deficiencies?
- blood loss from anywhere
- increased demand - pregnancy/growth
- reduced intake - diet/ malabsorption
- menstrual loss
How do we treat low iron?
- oral iron (often unreliable as some people do not absorb iron very well)
- IV iron - increased use
What are the characteristics of megaloblastic anaemia?
- a characteristic cell morphology caused by impaired DNA synthesis
- abnormal appearance of red cells
- raised MCV –> big red cells
- less RBCs –> aren’t produced properly
What are the causes of megaloblastic anaemia?
- B12 and/or folic acid deficiency
- alcohol
- drugs
- haematological malignancy
How does a lack of B12 and folate cause anaemia?
- folates are required for the synthesis of purine/ pyrimidine bases
- B12 is essential for cell folate generation
- so low folate or B12 starves DNA of bases
How do we absorb vitamin b12?
gastric parietal cells produce intrinsic factor which binds to B12 and is absorbed by receptors in terminal ileum
What are the clinical features of B12 or folate deficiency?
- megaloblastic anaemia
- can have pancytopenia if more severe
- mild jaundice
- glossitis
- anorexia
- sterility
What is pernicious anaemia?
anaemia caused by a deficiency of B12
-autoimmune associations
What is SACDS?
- subacute combined degeneration of the cord
- B12 deficient neuropathy
- demyelination of the dorsal and lateral columns
- peripheral nerve damage
How does SACDS present?
peripheral neuropathy paraesthesiae numbness and distal weakness unsteady walking dementia
How do we treat SACDS?
- B12 and folate until B12 deficiency excluded
- B12 and folic acid for life to build stores
What is haemolysis?
shortened red cell life
What are the causes of haemolysis?
- haemaglobinopathy (sickle cell)
- enzyme defects (G6PD)
- hereditary spherocytosis / elliptocytosis
- antibodies
- drugs, toxins
- heart valves
How do we test for the presence of haemolysis?
- anaemic
- high MCV, macrocytic
- high reticulocytes
- blood film
- raised bilirubin, LDH
What is AIHA and how do we treat?
Autoimmune haemolytic anaemia
manage with steroids/immunosuppresion
What are the features of anaemia of chronic disease?
- a common medical issue seen in malignant/ inflammatory/infectious diseases
- typically normal MCV
- reduced red cell production due to abnormal iron metabolism, poor erythropoietin response and blunted marrow response
What is hepcidin?
a regulator of iron absorption (from gut) and release from macrophages
What are the features of ACD?
- no other causes of anaemia (after other options have been eliminated)
- usually mild anaemia, normal MCV
- often raised inflammatory markers e.g CRP
- normal/high ferritin + low serum iron
