Anaemia Flashcards
What could cause reduced erythopoiesis?
Chronic kidney disease, empty bone marrow, parvovirus infection, marrow infiltrated by cancer cells
What is dyserythropoiesis?
Defective development of erythocytes
What conditions is anaemia of chronic disease often seen in?
Inflammatory conditions eg rheumatoid arthritis, lupus, IBS
TB, bronchiectasis
What are some features of anaemia of chronic disease?
Iron stored in macrophages is not released for use in bone marrow
Circulating red cells have reduced lifespan
Marrow lacks response to erythropoietin
Anaemia may be microcytic, normocytic or macrocytic
What is a clinical clue that it may be anaemia of chronic disease?
Often raised CRP and ferritin
What causes myelodysplastic syndromes?
Production of abdnormal clones of marrow stem cells
What is often detected in myelodysplastic syndromes?
Genetic change by looking at chromosomes in marrow cells
What happens to the red cells in myelodysplastic syndromes?
Red cells are defective and large so are prematurely destroyed
What usually develops as a result of myelodysplastic syndromes?
Acute leukaemia
What could cause haemoglobin abnormalities?
Lack of iron, deficiency in building blocks for DNA synthesis (eg vit B12, folate) and mutations in the genes that encode the globin protein
What is megaloblastic anaemia?
Macrocytic anaemia that results from inhibition of DNA synthesis during red blood cell production
How is anaemia defined?
Anaemia is defined as a haemoglobin concentration lower than the normal range.
Why can anaemia develop?
1) Abnormal erythorpoiesis
2) Abnormal haemoglobin synthesis
3) Abnormal function, structure or metabolism
4) Abnormal function of the RES
5) Excessive blood loss
What is pancytopenia?
Lack of red cells, white cells and platelets
What is aplastic anaemia?
Deficiency of all types of blood cell caused by failure of bone marrow development
What is thalassemia?
Results from decreased or lack of alpha or beta chain production, causing an imbalance in the composition of the a2b2 tetramer.
What does deficiency of Vit B12 and folate lead to?
Megaloblastic anaemia due to an inability of red cell precursor cells to synthesise DNA and therefore divide. Since nuclear maturation and cell division lag behind cytoplasm development, large (“mega”) partially replicated red cell precursors are released into the bloodstream with inappropriately, large nuclei and open chromatin.
What is folate converted to once absorbed?
Tetrahydrofolate (by intestinal cells before entering the portal circulation and much of this is taken up by the liver which acts a store)
What is the role of tetrahydrofolate in metabolism?
To act as a one-carbon carrier, accepting carbon units from sources such as serine, glycine, histidine and formate
What is the collection of the various one carbon
forms of tetrahydrofolate referred to as?
One carbon pool
What do recipient reactions of carbon from the one carbon pool include?
Synthesis of the base thymidine required for DNA synthesis, synthesis of the purine bases adenine and guanine required for both DNA and RNA synthesis and transfer of methyl groups to vitamin B12
What can folate deficiency lead to in pregnancy?
Neural tube defects in the fetus