L27 Disorders of Blood Flashcards
how would you describe a decrease/increase in :
RBC
WBC
platelets
Dec RBC = anaemia
Dec WBC = leukopenia
Dec patelets = thrombocytopenia
Inc RBC = erythryocytosis
Inc WBC = leucocytosis
Inc platelets = thrombocytosis or thrombocythemia
what are the major causes of thrombosis?
atherosclerosis cancer immobilisation surgery hypercoagulability (iinhibitor (PC, PS, AT) deficiencies) thrombocythaemia (high platelet)
how are haemotological malignancies classified?
blood cell linage:
- myeloid neoplasm or lymphoid neoplasm
location:
- leukaemia (blood) or lymphoma (lymph nodes)
whether it is acute (weeks/-blasts) or chronic (years/mature cells)
what is neoplasia and what are the 2 classes of genes implicated?
uncontrolled cell growth
Oncogenes: directly causative of cancer – includes growth factors and their receptors, DNA binding proteins
Tumour suppressor genes: loss of suppressor activity leads to cancer
what are myeloid malignancies?
heterogeneous disorders characterized by uncontrolled proliferation and/or blockage of differentiation of abnormalmyeloidprogenitor cells.
what may myeloid neoplasias be caused by?
Polycythaemia (inc RBC)
Thrombocythaemia (inc platelets)
Myelofibrosis (inc megakaryocyte)
Chronic myeloid leukaemia (increased granulocytes – Philadelphia chromosome 9 + 22 translocation)
what is leukaemia and how may levels in the blood change? symptoms?
Accumulation of white blood cells in the bone marrow and blood
bone marrow failure
dec RBC, dec platelets, but inc WBC. if disease advances, WBC dec due to BM failure
Blood hyperviscosity due to inc white cells causing respiratory or neurological symptoms
Infection if dec white cells
Tiredness/anaemia
Bleeding
what is lymphoma?
T or B lymphocyte neoplasia affecting lymph nodes.
can be hodgkin (characterised by presence of Reed-Sternberg cells, usually upper body)
or non-hodgkin (linked to epstein-barr virus, can affect lymph nodes all over body)
how low do haemoglobin levels have to be to be classified as anaemia and what are the common symptoms?
men = < 13.5 g/dL women = < 11.2 g/dL
tiredness pallor fainting tachycardia shortness of breath
what is the difference between acute and chronic anaemia?
acute - caused by large blood loss
chronic - vol of blood loss exceeds capability of haematopoiesis of bone marrow eg peptic ulcer
both are normocytic anaemia - cells are normal, but not enough of them
what are Colony-stimulating factors (CSFs) and lymphokines?
Colony-stimulating factors (CSFs) = involved in haemopoiesis of myeloid cells inc RBCs
lymphokines = involved in haemopoiesis of ,ymphocytes + NK cells
where is EPO produced?
Epo is produced by interstitial fibroblasts in the kidney, hence why renal disease can lead to anaemia
which type of anaemia does iron deficiency cause and what can be the causes of this deficiency?
reduced haem production = microcytic anaemia (pale + small RBC)
causes: diet blood loss infection (hookworm) growth spurts, pregnancy
what does hypochromic, anisocytosis, and poikilocytosis mean?
hypochromic = less haemoglobin in each RBC
anisocytosis = variation in size
poikilocytosis = variation in shape
how does vit B12 and folate influence anaemia?
Vit B12 and folate involved in DNA replication
Deficiency of either causes problems with mitosis (cell division) of the proerythroblast
This causes megaloblastic or macrocytic anaemia (large RBCs)
Vit B12 deficiency mostly caused by reduced absorption
Folate deficiency may be caused by poor nutrition, alcoholism, malabsorption, certain drugs (anti-epileptics/antibiotics)
what is megaloblastic anaemia?
caused by folate or Vitamin B12 deficiency, leads to larger than normal RBCs and includes the formation of macroovalocytes (thin arrows) and also may lead to hypersegmented neutrophils (thick arrow, due to disordered nuclear maturation).
what is haemolytic anaemia?
Due to increased RBC destruction
RBC lifespan down from 120 to as little as 20 days
Bone marrow unable to replace sufficient RBCs
Acquired (malaria, sepsis)
Inherited (G6P dehydrogenase, Autoimmune Hemolytic Anemia)
what are some differences/examples of immune and non-immune haemolytic anaemia?
Immune:
Haemolytic syndrome in the newborn (Rh)
Autoantibodies
Complement
Non-immune: Drug-induced Snake venom Mechanical (heart valves) Infections (malaria, septicaemia)
which RBC cytoskeletal defect causes anaemia?
Mutations in a or b spectrin -> Hereditary spherocytosis
Cytoskeleton of RBC is made of spectrin which makes them able to be flexible. With damaged or no spectrin the RBC are a spherical shape and are unable to squeeze through places
which RBC enzyme defect causes anaemia?
Glucose-6-phosphate dehydrogenase (G6PD) deficiency, involved in NADPH metabolism
which haemoglobin defects cause anemia?
sickle cell
thalassaemia
what is the cause and effect of sickle cell disease?
cause:
Mutation in the Hb b globin gene Glu 6–>Val
Polymerisation of Hb, distorting RBC
Widespread in Africa (Carribean), Middle East, India and Med
effect:
“Sickling” of RBC (particularly in homozygous disease)
Sickle cell crisis due to blockage of microvasculature
Heterozygosity confers protection against malaria
what is thalassaemia?
Microcytic anemia
Defects in either the alpha or beta chains of hemoglobin, leading to ineffective erythropoiesis and hemolysis
a-thalassemia:
Prevalent in Africa, Mediterranean, Middle East, Asia
b-thalassemia:
Prevalent in Mediterranean, South East Asia, India, PakistaN
