Week 3 Flashcards
Describe the bone marrow micro-environment:
- Stroma is the bone marrow microenvironment that supports the developing haemopoietic cell
- Stromal cells supported by an ECM
- Stromal cells: macrophages, fibroblasts, endothelial cells, fat cells and reticulum cells
- ECM: fibronectin, haemonectin, collagen, proteoglycans and laminin
What is a clonal disorder of haemopoietic stem cells (HSC)?
Haematological malignancies and pre-malignant conditions are termed “clonal” if they arise from a single ancestral cell
What are myeloproliferative disorders?
Clonal disorders of haemopoiesis leading to increased numbers of one or more mature blood progeny
- variably associated with the JAK2 and calreticulin mutation
- have potential to transform into AML
What are common myeloproliferative disorders?
- Polycythaemia rubra vera (PRV)
- Essential thrombocytosis
- Myelofibrosis
Describe fanconi anaemia:
- 10-20% of aplastic anaemia cases
- Bone marrow failure may present from birth into adulthood
- Autosomal recessive inheritance
- Characteristics
- somatic abnormalities
- bone marrow failure
- short telomeres
- malignancy (very common)
- chromosome instability
- 7 genetic subtypes (A-G)
How are abnormal blood cells produced?
- Secondary to previous chemotherapy or radiotherapy
- Often associated with acquired cytogenetic abnormalities
- Characterised by dysplasia and ineffective haemopoiesis in >1 of the myeloid series
How is ET managed?
- Low risk (age <40 with no high risk features)
- Aspirin or anti-platelet agent
- Intermediate risk (age 40-60 with no high risk features)
- Aspirin +/- hydroxycarbamide
- High risk (aged >60, or other RFs (CVD, diabetes)
- First line therapy is same as intermediate risk, second line is anagrelide + aspirin
What is hydroxycarbamide?
Ribonucleotide reductase inhibitor (“gentle chemotherapy”)
How is iron transported in plasma, and what is the transporters iron saturation?
Transferrin (a glycoprotein synthesised in hepatocytes). 30% saturated with iron
Where does iron absorption take place?
Predominantly in the duodenum (duodenal enterocytes)
Is haem iron or non-haem more readily absorbed?
Primarily in the duodenum and upper jejunum
How much iron is lost each day, and how is it lost?
1 mg of iron is lost each day through sloughing of cells from skin and mucosal surfaces, including the lining of the GI tract. Menstruation increased the average daily iron loss to about 2 mg per day in premenopausal female adults
How does iron absorption occur?
At physiological pH, ferrous iron (Fe2+) is rapidly oxidised to the insoluble ferric (Fe3+) form. Gastric acid lowers the pH in the proximal duodenum, enhancing the solubility and uptake of ferric iron. Absorption is enhanced by Vit C, citric acid and inhibited by phytates and tannins (tea)
What are the requirements for normal red cell production?
EPO, correct genes to make haemoglobin, and iron, folate and B12 for erythropoiesis, as well as functioning blood marrow
What is the pathophysiology of iron deficiency anaemia?
Lack of iron to make haemoglobin, so reduced oxygen saturation of RBCs
Caused by:
- Dietary (in premature neonates or adolescent females)
- Malabsorption (e.g. in coeliac)
- Blood loss (most common cause, assumed to be GI until proven otherwise)
What is the pathophysiology of anaemia of chronic disease?
- Failure of iron utilisation as iron is trapped in RES
- Common
- Causes
- Infection
- Inflammation (RA, IBD)
- Neoplasia
- Anaemia of chronic renal failure = ACD + decreased EPO
What diseases cause anaemia?
- Haematinic deficiencies
- ACD
- Globin disorders
- Haemolysis
Describe the importance of B12/folate:
- Essential for DNA synthesis and nuclear maturation
- Required for all dividing cells, deficiency noted first in RBCs
- Deficiency results in megaloblastic anaemia initially, but will affect other organs
- B12 absorbed with intrinsic factor in the terminal ileum
What is the general pathology of anaemia?
Caused by reduced production or increased destruction/loss of red blood cells