6a: Haematology in systemic disease Flashcards
What three things must we consider when we think about things influencing patient blood counts
- Cause
- Complications (bc of systemic disease)
- Treatment
What are the causes of reduced erythropoeisis?
- Empty bone marrow unable to respond to stimulus from EPO eg after chemotherapy or toxic insult such as parvovirus infection or in aplastic anaemia
- Marrow infiltrated by cancer cells or fibrous tissue (myelofibrosis) means the normal haemopoietic cells are reduced
- Lack of response to the haemostatic loop – eg in chronic kidney disease the kidney stops making EPO
What is Anaemia of Chronic Disease/inflammation?
Anaemia of chronic disease (also called anaemia of inflammation) is a common cause of anaemia (2nd worldwide after iron deficiency) associated with chronic inflammatory conditions such as rheumatoid arthritis, chronic infections (e.g. tuberculosis) and malignancy
How is RBC production control?
What is anaemia of chronic disease an example of?
Dyserythropoiesis
How does anaemia of chronic disease occur?
- Iron dysregulation: iron not released for use in bone marrow
- The marrow shows a lack of response to erythropoietin
- Reduced lifespan of red cells
What is a functional iron deficiency?
Sufficient iron in the body but not available to the developing erythroid cells
Describe the importance of macrophages in supplying iron
- In bone marrow, erythroid cells develop in islands surrounding a nursing macrophage
- Macrophage takes the iron and gives to RBCs that need it
- Macrophages ‘eat’ old senescent RBCs and recycle iron
- Iron recycling is the main source of iron for new rbc
- Small amount of iron absorbed from gut
What is Hepcidin?
- Degrades ferroportin a protein involved in moving iron out of cells
- Prevents iron release from macrophages
- Prevents iron absorption from gut
What is hepcidin regulated by?
- HFE (hereditary haemochromatosis)
- Transferrin receptor
- Inflammatory cytokines - MOST IMPORTANT
Outline the causes for Anaemia of Chronic Disease/inflammation due to inflammatory cytokines
- Iron dysregulation: iron not released for use in bone marrow
- The marrow shows a lack of response to erythropoietin
- Reduced lifespan of red cells
How does Chronic kidney disease result in anaemia?
- Deficiency of erythropoietin production by the damaged kidneys
- Lower level of erythropoiesis in bone marrow leading to insufficient red cell production and anaemia
- Reduced clearance of hepcidin from blood
- Increased hepcidin production due to inflammatory cytokines
- Reduced lifespan of RBC as a direct effect of uraemia
- Dialysis-damage to rbc and loss due to bleeding
List some investigations for chronic kidney disease
- Often normocytic normochromic or microcytic anaemia
- Normal or high ferritin (iron stores)
- Normal or high Reticulocyte Haemoglobin content (CHr)
- CRP often elevated
How do we treat anaemia of chronic disease?
- Treat underlying condition – need to reduce inflammation and reduce the number of cytokines circulation
- Recombinant human erythropoeitin – can be given if associated renal failure. Only effective in patients with sufficient iron, folate and B12 to support an increase in erythropoiesis
- Vit B12 folate - to ensure and iron stores are adequate
- Transfuse - if all else fails and patient is symptomatic (and sparingly)
Describe the management of the chronic renal failure
Describe how chronic kidney disease can cause uraemia and some consequences of this
- Kidney dysfunction can result in uraemia (increase in urine concentration)
- Can inhibit erythropoiesis
- Reduces the lifespan of existing red blood cells as well as inhibiting platelet function
- Can cause chronic bleeding from the gastrointestinal tract
Discuss why there may low or high platelet count in chronic kidney disease
Low:
- direct effect of uraemia on platelet production
- drugs
- Haemolytic uraemic syndrome
High
- Reactive
- bleeding
- iron deficiency